EVIDENCE BASED MEDICINE A new approach to clinical care and research Developed and presented by Judy Tarselli, RN Dubai, UAE Karachi, Pakistan October 2003 Organized by NKF cyberNephrology University of Alberta, Canada www.cyberNephrology.org Special thanks to our sponsors Janssen-Cilag PROGRAM OUTLINE 1. 2. 3. 4. 5. 6. 7. Definition of EBM Basic Steps Trials, Studies and Reports Pros, Cons and Limitations EBM in Developing Countries EBM Library Advanced EBM But first, a test… WHAT IS THE BASIS OF YOUR MEDICAL PRACTICE? (Check all that apply) A. Training, clinical experience and consultation with other professionals B. Convincing evidence (non-experimental) from articles, case reports, product literature, etc. C. Preferences of the patient D. Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis Reports WHAT IS THE BASIS OF YOUR MEDICAL PRACTICE? EXCELLLENT! A. Training, clinical experience and consultation with other professionals B. Convincing evidence (non-experimental) from articles, case reports, product literature, etc. C. Preferences of the patient D. Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis Reports BUT… Past knowledge and practice might be outdated or inadequate Graduate Medical School Practiced Physician WHAT IS THE BASIS OF YOUR MEDICAL PRACTICE? FANTASTIC! A. Training, clinical experience and consultation with other professionals B. Convincing evidence (non-experimental) from articles, case reports, product literature, etc. C. Preferences of the patient D. Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis reports BUT… This evidence may be biased, outdated, incorrect, or not applicable to your patient JOURNALS (1987 to present) ARTICLES ADVERTISEMENTS WHAT IS THE BASIS OF YOUR MEDICAL PRACTICE? WONDERFUL! A. Training, clinical experience and consultation with other professionals B. Convincing evidence (non-experimental) from articles, case reports, product literature, etc. Mutual Respect + Shared Goals = Better Cooperation and Compliance C. Preferences of the patient D. Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis reports The patient should be involved in all important decisions But this is NOT always an easy task! And conflicts WILL occur! No salt? Lose weight? Forget it! Just give me a pill! I WON’T take that medicine… The side effects are INTOLERABLE! But doctor, I DO want to have children! And conflicts WILL occur! No salt? Lose weight? Forget it! Just give me a pill! I WON’T take that medicine… The side effects are INTOLERABLE! But doctor, I DO want to have children! Education about current alternatives and risks is often needed… for both the Patient and the Doctor! Wow… I never knew that high blood pressure could be so dangerous at my age! Yes, I’d like to try that new medication! I’ll discuss those risks with my husband. Education about current alternatives and risks is often needed… for both the Patient and the Doctor! An important rule in Evidence Based Medicine… It STARTS with the patient and ENDS with the patient. The patient’s preferences MUST be considered! WHAT IS THE BASIS OF YOUR MEDICAL PRACTICE? WOW!!! SUPERB!!! A. Training, clinical experience and consultation with other professionals B. Convincing evidence (non-experimental) from articles, case reports, product literature, etc. C. Preferences of the patient D. Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis reports In the practice of Evidence Based Medicine, it is the physician’s duty to find the best and most current information and apply it judiciously for the benefit of the patient. But… A practice based exclusively on science and math is effective only if your patients are robots or clones! Don’t forget to allow for individual human differences and personal preferences! WHAT IS THE BASIS OF YOUR MEDICAL PRACTICE? If you checked all 4 items… A. Training, clinical experience and consultation with other professionals B. Convincing evidence (non-experimental) from articles, case reports, product literature, etc. C. Preferences of the patient D. Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis reports CONGRATULATIONS! You are practicing EVIDENCE BASED MEDICINE! A. Training, clinical experience and consultation with other professionals B. Convincing evidence (non-experimental) from articles, case reports, product literature, etc. C. Preferences of the patient D. Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis reports EVIDENCE BASED MEDICINE A new approach to clinical care and research 1. 2. 3. 4. 5. 6. 7. Definition of EBM Basic Steps Trials, Studies and Reports Pros, Cons and Limitations EBM in Developing Countries EBM Library Advanced EBM “What is Evidence Based Medicine?” “And where did it come from?” A BRIEF HISTORY 1980’s: McMasters University in Ontario, Canada Dr. David Sackett and colleagues proposed Evidence Based Medicine (EBM) as a new way of teaching, learning and practicing medicine. Dr. Sackett defines EBM as: “…The conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients.” Evidence Based Medicine It is a change in the way physicians practice medicine, teach and learn, and handle research. Clinical practice: Based on the best current evidence (not necessarily on how it’s always been done) Patient Care: Compassionate, patient-oriented (less authoritarian) Learning & Teaching: Problem-based, problem-solving more investigative, less know-it-all-by-yesterday Research: More stringent approach, better proof criteria (more demanding of proof, less room for error) THREE MAJOR COMPONENTS of EBM PATIENT Question or Problem PHYSICIAN INFORMATION THE ADDED DETAILS PATIENT Values, Concerns Preferences, Expectations Life predicament EBM PHYSICIAN Training & Experience Current Expertise Continued learning Demand for proof INFORMATION Clinically relevant Proven by research Best up-to-date evidence OPTIONAL COMPONENTS PATIENT Values, Preferences Concerns, Expectations Life predicament TO BE ADDED BY THE PHYSICIAN CHARITY EBM is not a required practice (yet) HUMILITY Non-authoritarian practice EBM PHYSICIAN Training Expertise Continued Learning Demand for proof INFORMATION Clinically relevant ENTHUSIASM Challenge, Variety, Proven by research Current, up to date Change “Isn’t this the way we have always practiced medicine?” “Aren’t these just the same old ingredients tossed into a new recipe?” When am I supposed to find the time to do that? The basic steps of EBM THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process The Clinical Question The FIRST step The HARDEST step The MOST IMPORTANT step! FACT: We all have informational needs! That is not a problem! Problems arise • if we fail to recognize those needs • if we fail to bridge the information gap • if we fail to ask the right questions Asking good questions is a skill to be learned. Lee, exactly how much time did you spend on that big project? It will make life easier for you... And also for others around you! Hmmm… Is he about to give me a BONUS? Or is he about to FIRE me? Lee, can you give me an accounting of the extra time you spent on that project so that I can charge it back to the client? A GOOD QUESTION… • Is focused and relevant • Provides clear communication • Clarifies your goal or need • Will reduce the amount of time needed to obtain the answer Oh sure! I’ll have it on your desk by tomorrow! WHEN PRACTICING EBM, a good question must also: • Be specific Identify the problem, clarifiy the clinical issue • Be answerable through the literature • Contain multiple aspects (patient, options, comparisons, etc) ACTUAL CASE SCENARIO Large cauc male, age 40 2mo ago: Presented with classic nephrotic syndrome, significant symptoms. Bx showed IgAN. Cr 1.4, incr to 2 range, now 1.6 Tried prednisone 60mg qd tolerated poorly w/tremors and depression. Needs new regimen, but others are aimed more at nephritic IgA rather than nephrotic syndrome. Suggestions? It should NOT involve a question of Personal Preference or Local Concern. THE EVIDENCE BASED RESPONSE Posted on Nephrol 4/13/03 Respondant recommends cyclophosphamide and prednisolone (assuming secondary causes excluded) - a combination that allows for lower dose prednisolone… “In the study below, proteinuria and renal function improved on this combination: Ballardie FW, Roberts IS. Controlled prospective trial of prednisolone and cytotoxics in progressive IgAN. J Am Soc Nephrol 2002 Jan….” “I have patients on this regime who have benefitted.” Regards, Dr. Paulose P. Thomas Nephrologist - Belhoul Apollo Hospital, Dubai, UAE BACKGROUND and FOREGROUND QUESTIONS (all part of EBM) FOREGROUND QUESTIONS NEW POSSIBILITIES INDEFINITE ANSWERS “Where do we want to go, and how else might we get there?” “Where are we now? And which way are we headed?” BASIC & CONCRETE BACKGROUND QUESTIONS STUDENT GRAD EXPERT BACKGROUND QUESTIONS BASIC & CONCRETE 1. QUESTION • Who, What, Where, When, Why, How 2. VERB • is, causes, does, treats, reduces, cures, prevents, affects 3. GENERAL KNOWLEDGE ABOUT DISORDER clinical manifestations of disease, patient findings, differential diagnosis, etiology, patient experience, comorbid condition, screening and diagnostic tests, prognosis, therapy, risk factors, etc. STUDENT GRAD EXPERT FOREGROUND QUESTIONS NEW POSSIBILITIES INDEFINITE ANSWERS PT AND/OR PROBLEM Differential dx, Unusual presentation, uncertain etiology, pt’s prior experience, comorbid conditions INTERVENTION Exposure, test. Prognostic factor, treatment, pt perception, etc. COMPARISON INTERVENTION OUTCOMES STUDENT GRAD EXPERT EBM QUESTION: Should include multiple factors (Examples) P PATIENT type of patient or population Ex: 47 yr male w/DM2 and cellulitis toe, 25 yr female w/DVT and chest pain E EXPOSURE environmental, personal, biological Ex: TB, tobacco, drug, diet, pregnancy or menopause, MRSA, allergy I INTERVENTION clinical intervention Ex: medication, procedure, test, surgery, radiation, drug, vaccine C COMPARISON compare alternative treatment Ex: other prior, new or existing therapy O OUTCOME clinical outcome of interest Ex: Reduced death rate in 5 yrs, decreased infections, fewer hospitalizations FRAMING THE QUESTION (Example: PICO) ELEMENT PROMPTS THE QUESTION: Patient Intervention Comparison Outcome How would I describe a group of patients similar to mine? What main action am I considering? What is/are the other options? What do I (or the patient) want to happen (or not happen)? Example: P: In kids under age 12 with poorly controlled asthma on metered dose inhaled steroids… I: would the addition of salmetrol to the current therapy C: compared to increasing the dose of current steroid O: lead to better control of symptoms without increasing side effects? CATEGORY OF QUESTION MAJOR CATEGORIES 1. 2. 3. 4. Diagnosis Prognosis Therapy/ Treatment Harm (iatrogenic, other) MISCELLANEOUS • Quality of care • Health economics • Office Management • Etc. PICO PEO THE PATIENT’S QUESTIONS Must be considered! Often QUALITATIVE (not based on measureable outcomes) Feelings, ideas, experiences, preferences, concerns, fears, beliefs, ethnicity Usually based on LIMITED BACKGROUND Perception of problem Self-diagnosis Treatment wanted or needed Alternatives (read, heard, considered, tried) What is the patient hoping to avoid? What benefits does the patient want or need most? Etc. QUANTITATIVE vs QUALITATIVE QUESTIONS QUANTITATIVE: “Solid Evidence” • Measurable answer or response • Necessary for scientific study • Necessary for the practice of EBM QUALITATIVE: “Quality of Life” • “Fuzzy” data - Impact on daily life, work, family, etc. • May be very important and influential to decisions – especially for the patient • Creates added challenge or twist to practice of EBM QUALY: QUALITY ADJUSTED LIFE YEAR CHRONIC MEDIOCRITY PERFECT HEALTH 10 9 8 7 6 5 4 3 2 1 2 3 4 5 6 7 8 9 10 10 9 8 7 6 5 4 3 2 1 3 4 5 6 7 8 9 10 5-yrTREATMENT COMPARISON DETERIORATING HEALTH 9 8 7 6 5 4 3 2 1 0 2 10 8 Chemo&Rad 6 4 Radiation only 2 Chemo only 0 2 3 4 5 6 7 8 9 10 1 2 3 4 5 THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process Find the Best Evidence “The Literary Search” HINT: If your desk looks like this, it’s probably the LAST place you should start looking! Find the Best Evidence “The Literary Search” The BEST EVIDENCE is: External - from outside resources (researchers, experts) Current – not out of date, most recent High Quality - accurate, precise, effective, safe Patient focused - applicable and appropriate for your individual patient FIVE STEPS TO FINDING THE BEST EVIDENCE 1. IDENTIFY NEEDS: What type of information is needed? 2. IDENTIFY RESOURCES: Types, Availability, Timeliness,Costs? 3. SEARCH & RETRIEVE: Use efficient strategies 4. REVIEW : Check quality and usefulness of info 5. INTERPRET: Help patient understand info, application WHAT TYPE OF INFORMATION IS NEEDED? WHAT CATEGORY IS THE QUESTION? • • • • Diagnosis Prognosis Therapy Harm WHAT STUDY DESIGN FITS IT BEST? There are MANY study designs! EXPERIMENTAL TRIALS (Answers questions of diagnosis or treatment) Randomized Controlled Trials (RCTs) Controlled studies Blinded vs Open ETC. OBSERVATIONAL STUDIES Descriptive reports Retrospective studies Cohort studies Case Control ETC. EXAMPLE Randomized Controlled Trials (RCT) “Gold Standard” of research Ideal experimental design - Best design for TREATMENT questions Must identify objective of treatment (Ex: cure, prevent complication, palliation, reassurance) Still not always the right intervention for individual patient at that particular time and place What type of evidence best addresses the question, problem or issue? CLINICAL PRACTICE APPROPRIATE DESIGN FOR CLINICAL RESEARCH Diagnosis, Dx testing Cross-sectional study – not randomized trial Prognosis Follow-up studies of patients evaluated at same early point of illness Therapy, treatment RCT or Systematic review of multiple RCTs must be used Avoid non-experimental approaches to avoid false conclusions about efficacy Exceptions: When treatment may be successful in an otherwise fatal condition When no studies are available (rare conditions, new treatments, etc.) Harm RCT, Cohort, Case-control OTHER INFORMATIONAL Explore hypothesis History-taking Individual trial & error Following clinical course Recordkeeping Quality of Care research Qualitative research Case control study n of 1 trial Cohort study Systematic registry-based (computer supported) research Individual peer review, Process Evaluation MISCELLANEOUS Basic Science, Genetics, Immunology, etc. WHAT FORM OF INFORMATION? Case report Controlled Trial Systematic review Meta-analysis Clinical guidelines etc. LITERARY SEARCH: NEXT STEP IDENTIFY YOUR RESOURCES Colleagues Consultation, Discussion (Caution: Response may be an outdated “This is what we do”) Paper resources books, reports, journals Electronic databases Health Literature Services specialized librarians, staff Review services, Abstract Services, etc. SEARCH AND RETREIVE THE BEST EVIDENCE Learn and Practice various SEARCH STRATEGIES: • To find useful information quickly • To eliminate irrelevant, inappropriate or weak information Try to develop the habit of learning as you go; Not just in lengthy formal sessions! LITERARY SEARCH STRATEGY ASK FOR HELP! SPECIALIZED PERSONNEL • track down information, textbooks, articles, guidelines • may provide electronic search support or training EXAMPLES • Medical Librarians • Medical Informatics Specialists • Specially trained staff member LITERARY RESOURCES • TEXTBOOKS (caution – most obsolete!) • Traditional • Evidence Based • JOURNALS (may be outdated) • REVIEW ARTICLES (summaries, abstracts) • SYSTEMATIC REVIEWS (prepared in systematic, rigorous manner) Ex: Cochrane Collection • META-ANALYSIS • CLINICAL PRACTICE GUIDELINES Summarized and easily digestible information ELECTRONIC RESOURCES, DATABASES, INTERNET Bibliographic Database Example: Medline, PubMed Medical Information Services: Medscape, HDCN Review Services Subjective Systematic Reviews Meta-analysis Examples: • Cochrane, • Best Evidence, • Up to Date MORE GREAT INTERNET RESOURCES Websites cyberNephrology, National Kidney Foundation. NIDDK, American Heart Association, American Cancer Society. National Institutes of Health, etc Listserve Discussion Groups CyberNephrology, C-span, etc. Specialty Electronic Databases Psyclit CancerLit CINAHL (allied health and nursing journals) Etc OTHER RESOURCES Tapes Videos CD-ROMs Specialty seminars Product information and comparisons A closer look at some Internet Resources… MEDLINE WHAT IS IT? Searchable database of medical information compiled by National Library of Medicine in US 1966-present Catalogs articles from approx 4000 world journals (of estimated 12-15k total) SEARCH METHODS Any word or words (title, abstract, content, author name, institution, etc.) Medical Subject Heading (MeSH) terms A restricted thesaurus of medical titles Articles categorized by most specific possible MeSH heading COST: FREE! Or may subscribe to companies with specialized search strategies: • Ovid Technologies (ovid) • Silver Platter Information (WinSPIRS) BENEFITS Free Vast database LIMITATIONS Not all articles are indexed on Medline (only 1/3 of approx 10 million!) Much material listed and described on Medline can only be accessed through journal article MEDLINE: ELECTRONIC SEARCH STRATEGIES Search through “Clinical Queries” service of PubMed http://www.ncbi.nlm.nih.gov/clinical.html Medical Subject Headings (MeSH) Search filters Search by a text word can supplement a MeSH search Boolean search: “and”, “not”, etc. To increase sensitivity • use “explode” command • avoid using subheadings Online Tutorial is available! COCHRANE LIBRARY Cochrane Database of Systematic Reviews -systematically compiled reviews of intervention Cochrane Controlled Trials Register -citations of controlled trials identified anywhere in the world Cochrane Review Methodology Database -methodological papers relating to systematic reviews Etc. BEST EVIDENCE Electronic version of two publications: • Evidence Based Medicine • American College of Physicians Journal Club Covers broad topics of information THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process CRITICAL APPRAISAL Interpreting the evidence • How to read a paper • How to do the math CRITICAL APPRAISAL IMPORTANT! You do NOT have to become a researcher, epidemiologist, or statistician to practice EBM. Focus on how to USE research reports – not on how to generate them! CRITICAL APPRAISAL HOWEVER… You must have a solid understanding of basic research principles and study designs in order to understand and interpret the evidence! TYPES OF STUDIES AND REPORTS Randomized Controlled Trial - “The Gold Standard” Systematic review Meta-analysis Retroactive vs Prospective Incidence Prevalence Case Control Cohort (Follow-up) Cross-sectional Ecologic Longitudinal Experimental Blinded vs Open Qualitative Screening DETOUR BASIC RESEARCH PRINCIPLES STUDY DESIGNS THE TIME FACTOR When was the study done? What was its duration? In what time direction is it headed? RETROSPECTIVE PROSPECTIVE THE TIME FACTOR When was the study done? What year? What technology? (ie: test, drug, equipment, procedure) Any associated social factor or historical event? THE TIME FACTOR What was the Study Duration? Was it an appropriate length of time for the intended goal? Limited time study or ongoing? Was study completed? Stopped early? In what direction is it headed? RETROSPECTIVE “LOOKING BACK” Historical Review or Investigation PAST PROSPECTIVE “LOOKING FORWARD” Future Results The Great Unknown PRESENT FUTURE In what direction is it headed? RETROSPECTIVE PROSPECTIVE PRO •Lower risk of bias PRO •May provide good direction for future study CON: May get faulty results based on incomplete data or insignificant subgroups “Hind Sight is 20/20” CON: •Prone to Bias •A“Fishing Expedition” for positive results PRESENT (Example of Error: Untreated hypertension unlikely to cause cardiac event in child, so treatment is unnecessary below age 18yrs) “Was there a similar comparison group?” No comparison group All subjects receive Experimental Intervention Experimental Intervention UNCONTROLLED STUDIES NO EVENT Experimental Intervention OUTCOME EVENT “Trial and Error?” or “Before & After?” UNCONTROLLED STUDIES Generally NOT accepted: Potentially Dangerous and Flawed Prone to BIAS! “Traditional Study Method” May produce strong results “Trial and Error” “Before & After” PROBLEMS BENEFITS POSITIVE OUTCOME MAY BE DUE TO: •Other factors •Natural course of disease (some get better, some don’t!) Can answer some questions about: •likelihood of response •adverse effect, etc. •Spontaneous change of health •Placebo Effect VERY PATIENT-SPECIFIC! •Hawthorne Effect NEGATIVE OUTCOME May be due to study treatment. Could be disastrous! MAY BE ONLY OPTION Rare conditions Previously unknown conditions UNCONTROLLED TRIALS: “TRIAL AND ERROR” Example#1 SMALLPOX VACCINATION James Phipps, age 8 years GOOD! Resistant to Cowpox and Smallpox (NO DISEASE OUTCOME) SMALLPOX VACCINE 1. 1796: Edward Jenner inoculates 8yr-old James Phipps with cowpox virus from a milkmaid’s hands. Child develops illness, recovers. 2. Two weeks later, inoculates same child with smallpox virus. Child survives, no illness. (Centuries later, smallpox eradicated!) n=1 UNCONTROLLED TRIALS: “TRIAL AND ERROR” Example #2 Drinks culture of H.pylori Dr. Marshall Microbiologist n=1 NO OUTCOME SEVERE GASTRITIS HELICOBACTER PYLORI - GASTRIC ULCERS 1982: Australian microbiologist Barry J. Marshall presents evidence showing a possible infectious cause for gastric ulcers. Suggests they may be treatable with antibiotics. Findings are met with disinterest and disbelief by medical community. Lacks support for further study. 5 years later: Prepares a broth of live organisms isolated from a gastric ulcer patient and drinks it. Becomes violently ill, develops severe acute gastritis. 1990’s Antibiotics are used routinely to cure some gastric ulcers! UNCONTROLLED TRIAL RECOVERED Experimental Intervention May represent the ONLY treatment option for a new or rare disease Present DIED FUTURE STRONGLY PREFERRED! Reduces BIAS. Provides stronger results. Experimental Intervention Control Group CONTROLLED STUDY Only the TEST group receives the Experimental Intervention ExperimentalI ntervention Control group may receive… Nothing Placebo Observation only Other IMPORTANT All other differences should be minimized or eliminated to reduce potential BIAS Gold Standard Treatment RANDOMIZED CONTROLLED TRIAL (RCT) “The Gold Standard” Experimental Intervention Control Group THE FIRST RANDOMIZED CONTROLLED TRIAL By Sir Austin Bradford Hill Streptomycin (n=50) (BLINDED) Bedrest (n=50) 1944 TUBERCULOSIS TREATMENT: Streptomycin vs Bedrest OPEN vs BLINDED STUDIES Experimental Intervention OPEN Control Group OPEN vs BLINDED STUDIES BLINDED TRIAL BLINDED BLINDED TRIAL BLINDING SINGLE BLINDED: Pt unaware of what group s/he is in DOUBLE BLINDED: Pt and MD unaware OPEN LABEL: Everyone is aware RANDOMIZED vs NON-RANDOMIZED TRIALS Experimental Intervention How is this group divided? Control Group NON-RANDOMIZED Experimental Intervention Assigned to groups, usually by the researcher Control Group Potential for RESEARCHER BIAS! RANDOMIZED Experimental Intervention Random method of assignment used Control Group Maximizes “sameness,” Eliminates BIAS! RANDOMIZED CONTROLLED TRIAL (RCT) (EXPERIMENTAL TRIAL) Experimental Intervention “The Gold Standard” Control Group Present FUTURE One patient, series of tests n=1 TRIAL SERIES FOR INDIVIDUAL PATIENT GOOD GOOD Experimental Intervention Experimental Intervention Trial of Medicine 1 Trial of Medicine 2 Or placebo Or placebo NO CHANGE OR BAD NO CHANGE OR BAD Why a TRIAL SERIES for one patient? BENEFIT Produces data most applicable to the individual patient EXAMPLES: Trial of different medications and/or placebo for child reported to have ADHD symptoms that are not clinically apparent Trial of different analgesics for patient with chronic pain from a combination of diseases not previously studied PATIENT •Must be blinded •Must keep diary or complete questionnaire PHYSICIAN •May need to be blinded (enlist help of pharmacist!) •Must treat patient as usual in all other respects CROSSOVER TRIALS ONE GROUP, MULTIPLE TESTS (Best if participants are blinded) Intervention A Intervention Intervention A Intervention B B ASSESS OUTCOMES #1 ASSESS OUTCOMES #2 COMPARE OUTCOMES CROSSOVER TRIALS PROS & CONS Fewer participants needed than a RCT! Intervention A Intervention Intervention A Intervention B B ASSESS OUTCOMES #1 ASSESS OUTCOMES #2 All are in experimental group Lower costs CROSSOVER TRIALS PROS & CONS MUST HAVE SHORT CARRYOVER EFFECT MUST HAVE SHORT WASHOUT EFFECT Intervention A Intervention Intervention A Intervention B B ASSESS OUTCOMES #1 ASSESS OUTCOMES #2 (OR WAIT A SUITABLY LONG WASHOUT TIME!) CASE CONTROL (“A LOOK BACK”) RISK FACTOR? (PAST) Present CASE CONTROL (“A LOOK BACK”) HEALTHY NEVER SMOKED RISK FACTOR LUNG CANCER SMOKER (PAST) Present CASE CONTROL (“A LOOK BACK”) NON-DIABETIC NORMAL WEIGHT RISK FACTOR DM TYPE II OBESITY Present COHORT“FOLLOWUP DESIGN” IS RISK FACTOR PRESENT? (Exclude those with outcome already!) Future Outcome COHORT TO INVESTIGATE ETIOLOGY OR HYPOTHETICAL CAUSE OF DISEASE/OUTCOME IS RISK FACTOR PRESENT? “FOLLOWUP DESIGN” Present Future Outcome COHORT EXAMPLE RISK FACTOR Hgb <9 DIALYSIS PATIENTS Present Measures future outcome for dialysis pts w/o treatment of anemia CROSS SECTIONAL DESIGN ? Cause ? Risk factors A look back CROSS SECTIONAL DESIGN OTHER CAUSES RISK = SLEEP PRONE SIDS DEATHS INFANT DEATHS Problems of looking back NON-SIMILAR CONDITIONS Social Personal Comorbid conditions Other treatments Etc. Not usually accepted by medical journals (accepted in popular press, not reviewed) VARIATION IN TREATMENT OR METHOD NO CONTROL OVER CONTROL GROUP CURRENT GROUP OF PATIENTS RANDOMIZED & CONTROLLED TRIAL (RCT) Experimental Intervention MAY BE BLINDED Control Group PROSPECTIVE START WITH YOUR TARGET POPULATION START WITH YOUR TARGET POPULATION Set CRITERIA for INCLUSION / EXCLUSION This will determine: ELIGIBILITY at the start VALIDITY at the end START WITH YOUR TARGET POPULATION ELIMINATE THOSE WHO DO NOT MEET THE CRITERIA NEXT: GATHER A SAMPLE GROUP THE SAMPLE GROUP WILL: •Represent the target population •Meet the criteria for inclusion / exclusion SIDE NOTES… Study should be approved by an Ethics Committee Informed consent should be obtained from study participants SAMPLE GROUP MAY BE SUBDIVIDED FURTHER STRATIFICATION Divide into subgroups based on important similar characteristics RANDOMIZATION Divide into sub-groups based on unknown confounders STRATIFICATION “important similar characteristics” Examples: • Male or Female • Age • Stage of illness • Prior illness or treatment • Hospital vs Office groups • Comorbid condition • Etc. EXAMPLE OF STRATIFICATION FEMALE MALE RANDOMIZATION “unknown confounders” Examples: • Postal code • Month of birth • Random number • Etc. EXAMPLE OF RANDOMIZATION DX IN JANUARY-JUNE DX IN JULY-DECEMBER Next… Divide your sample group(s) into STUDY GROUPS Experimental Intervention Control Group “Test Group” “Baseline Group” Next… Divide your sample group(s) into STUDY GROUPS “Test Group” Experimental Intervention Receives Experimental Intervention “Baseline Group” Control Group • • • • • Nothing Observation “Same” miscellaneous intervention (nonexperimental) Placebo “Gold Standard” therapy especially if unethical to do otherwise! ASSIGN PATIENTS TO STUDY GROUPS Experimental Intervention Use caution against bias! Control Group Sample Group Study Groups STUDY INVESTIGATOR usually assigns patients to study groups. Experimental Intervention usually has a personal preference for the treatment or patient might unconsciously Control Group “work harder” to make the study work with non-preferred candidates = POTENTIAL FOR BIAS RANDOMIZED CONTROLLED TRIAL (RCT) Experimental Intervention Use random separation and assignment! Control Group RANDOMIZED CONTROLLED TRIAL (RCT) Experimental Intervention Control Group RANDOMIZED CONTROLLED TRIAL (RCT) Experimental Intervention Control Group Present Proceed with study FUTURE RANDOMIZED CONTROLLED TRIAL (RCT) Experimental Intervention EXPERIMENTAL EVENT RATE (EER) Control Group CONTROL EVENT RATE (CER) RANDOMIZED CONTROLLED TRIAL (RCT) “The Gold Standard” Experimental Intervention EXPERIMENTAL EVENT RATE (EER) Control Group Present CONTROL EVENT RATE (CER) FUTURE Disadvantages of RCT Expensive large # pts needed Prolonged recruitment and follow-up time needed Funding difficult to obtain except w/support of pharmaceutical companies (problematic!) RETURN FROM DETOUR THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process CRITICAL APPRAISAL Interpreting the evidence • How to read a paper • How to do the math EVALUATE WRITTEN EVIDENCE FOR… Quality Usefulness …BY ASSESSING Validity Reliability Relevance Clinical importance Critical Appraisal: VALIDITY What was the original purpose of the study? When was it prepared? By whom? • • credentials? affiliations? Sample population Did the subjects represent an appropriate test group? How were they selected? Were controls used? Were groups similar for important prognostic characteristics? VALIDITY How was the information gathered and processed? Were groups treated equally except for trial therapy? Were appropriate criteria used to measure results? Were criteria applied rigorously? Was the study completed? (Or ended early for a specified reason?) Did the study account for all test subjects? Including subjects lost to follow-up? Were ALL pts analyzed in their allocated groups? (ie: INTENTION TO TREAT - not “completed treatment” analysis) VALIDITY Information Does the paper support its claims? Is the information accurately presented? Does it represent the truth? Results Are the results believable? To what degree of confidence? Ex: Disagreement is not uncommon on angiograms, EKGs, radiographs, pathology, PAP tests, etc. VALIDITY Comprehensiveness Size: Was it large enough to yield credible results? Thoroughness: Was it complete enough? Duration: Was it long enough? CRITICAL APPRAISAL: RELIABILITY Do we trust the information and results? 1. APPROPRIATE TYPE OF STUDY 2. REPRODUCEABILITY 3. INTERPRETATION OF RESULTS 4. BIAS RELIABILITY APPROPRIATE TYPE OF STUDY Was the type of study design used proper for the question? Example: RCT would be choice for questions on TREATMENT RELIABILITY Are the Measurements and Results reproducibile? Different determinations may be caused by: • Variation in measurement methods • Different interpretation of results • Lack of agreement Example: BP checks on same patient may vary. Are differences result of pt factor, examiner factor, treatment factor, normal variance Would the same results be obtained if patient is re-measured? (with identical procedure) • at another time? • by another person? Were any similar studies done? • Was the information comparable? • Did the results agree? RELIABILITY INTERPRETATION OF RESULTS Is there consistency among researchers? Different determinations may be caused by: • Variation in measurement methods • Different interpretation of results • Lack of agreement EXAMPLE: BANFF CONFERENCE - Setting standards in Transplant Pathology established by Kim Solez, MD Were any new questions or controversies raised by the study? RELIABILITY IS THERE ANY EVIDENCE OF BIAS? A dangerous pitfall! • PATIENTS • RESEARCHERS PATIENT BIAS Social Desirability Bias Patient responds in the way they perceive as correct Patient denies unhealthy behavior, gets misclassified • • Ex: Smoker vs Non-smoker to support MD to support a preconceived notion (ie: foods vs ADD) PATIENT BIAS Hawthorne Effect People act differently when they know they are being watched. Authors must take steps to reduce this bias by treating all equally! Ex: Follow more careful diet when regular weigh-ins are scheduled Ex: Weigh all patients with same frequency, even for group not on special diet RESEARCHER BIAS Who sponsored or funded the study? Personal gain or loss from results? Affiliates Special interests Conflict of interest Biased goal? To satisfy editors and reviewers… rather than solve real life clinical problems RESEARCHER BIAS Criteria bias? Risk-avoidance by researchers (will focus energy on topics that produce positive results) Bias toward patients? Sample selection criteria used (inclusive, exclusive) Assignment to test group or control - Random? Blind? RESEARCHER BIAS Data collection methods used • applied similarly to all subjects, including controls? • starting point – prospective/retrospective, stage of patient? • Was assessment blind? Data analysis • Were all potential subjects included in denominator or otherwise accounted? • Were they evaluated in originally designated group? (INTENTION TO TREAT) REDUCING OR ELIMINATING BIAS AND ERROR CONDUCT BLIND STUDIES • • Single Double-blinded USE INDEPENDENT OBSERVERS • • When doctor and/or patient can not be blinded, blinded IO measures outcome IO may even be unaware of study hypothesis USE MULTIPLE OBSERVERS Ex: Send subject slides to multiple pathologists for interpretation ESTABLISH CLEAR STANDARDS • • Exact methods to use to reduce variation in technique among researchers Clear wording on surveys, etc VALIDATING INSTRUMENTS • • Repeat screening to check for correct answers on surveys More frequent evaluations or surveys prevent guesstimates common to less frequent evaluation NEXT STEP IN CRITICAL APPRAISAL: RELEVANCE QUESTION: Is the report applicable to our… Problem? “Does it address the questions raised?” Patient(s)? “Will my patient respond like those in the study?” Practice? “Can it be done within my practice or circle?” ARE THE STUDY PATIENTS • Comparable within the study? (similar traits, age, socioeconomic group, stage of illness, treatment, etc.) • Comparable to your patient? ARE THE STUDY PROFESSIONALS • Comparable to you? (general/specialist, primary care/teaching hospital, etc.) NEXT STEP in CRITICAL APPRAISAL CLINICAL IMPORTANCE Information can be true and interesting in theory, yet useless in clinical practice! 1. Is the information clinically important? 2. If yes, how important is it? • study design - See: Hierarchy of Evidence • weight of results HEIERARCHY OF EVIDENCE (value of study design to maximize wt, minimize bias) 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. Systematic Review of all relevant RCTs At least one properly designed RCT Trials and case studies Well-designed Controlled Trial without Randomization Well designed Cohort or Case Control Studies, preferably from >1 centre or group Multiple Time series with or without intervention (Exception: Dramatic results in uncontrolled trials, such as introduction of PCN in the 1940s) Opinions of respected authorities, based on Clinical expertise Descriptive studies Reports of Expert Committees RANDOMIZED CONTROLLED TRIAL (RCT) Evaluation of RCT Were all clinically appropriate outcomes measured? Did an ethics committee approve the study? Any statistically significant results also clinically significant? Any significant adverse reactions? Was follow-up procedural analysis identical? Was continuous data analysis vs end of trial data used? Interpreting the evidence • How to read a paper • How to do the math HOW TO DO THE MATH Incidence Prevalence Statistical Formulas +/- Predictive Values - Probability - The p value Relative Risk Risk Reduction Odds Ratios NNT (Number Needed to Treat) – Risk Reduction Confidence Intervals Sensitivity and Specificity Regression Analysis Subgroup Analysis Health Status Evaluation Health Economics OUTCOMES: NOT “STUDY FAILURES” ACCOUNT FOR ALL even if •Non-compliant •Lost to follow-up OUTCOMES RELATE TO EVERYDAY CLINICAL PRACTICE, including… • Deaths • Poor compliance • Wrong treatment received • Lost to follow-up • Etc. Analyze as a member of the originally assigned group! Analysis SHOULD BE BASED ON • INTENTION TO TREAT • NOT on “completed treatment” analysis INCIDENCE & PREVALENCE NEPHROL, a service of NKF cyberNephrology 7/10/03 10:17:12AM Dear Nephrolers, I would like to know how to calculate incidence and prevalence of B and C virus in HD. Thank you in advance. Mario Cuba, MD Servicio de Nefrologia Hospital Lucia Iniguez Landin Holguin, Cuba INCIDENCE & PREVALENCE Response from Michel Jadoul, MD NEPHROL, a service of NKF cyberNephrology Prevalence: total number of positive patients divided by total number of patients: 20+/200=10% Incidence: number of new positive cases/total number of cases negative at start of period (e.g; year)/period (year?) thus : for instance 2 new positive cases /100 negative cases at start of year=2%/year. M.Jadoul, M.D. B PREVALENCE B 10 cases Hep B in 100 patients 10 / 100 = 0.10 B PREVALENCE = 10% B B B B B B B B INCIDENCE B B 1 year period 90 HBsA(-) at start of study B 5 new cases B 5 / 90 = 0.06 INCIDENCE = 6% per year B B B B B B B B B B B B RECALCULATED PREVALENCE B 16 cases Hep B in 100 patients 16 / 100 = 0.16 B B NEW PREVALENCE = 16% B B B B B B B B B B COMPARISON STUDIES: NEW DIAGNOSTIC TESTS COMPARING A NEW TEST AGAINST THE GOLD STANDARD TEST RESULTS OF GOLD STANDARD TEST EXPERIMENTAL TEST DISEASE PRESENT POSITIVE NO DISEASE TRUE (+) FALSE (+) a b NEGATIVE FALSE (-) c TRUE (-) d ACCURACY OF TEST - COMPARE TO GOLD STANDARD What is the usefulness of the test in various groups and subgroups of pts? TESTS ARE RARELY 100% ACCURATE EXPERIMENTAL TEST THEY MUST BE COMPARED AGAINST THE GOLD STANDARD TEST POSITIVE a+b TEST NEGATIVE c+d RESULTS OF GOLD STANDARD TEST DISEASE PRESENT a+c NO DISEASE PRESENT b+d TRUE (+) FALSE (+) a b FALSE (-) c TRUE (-) d ACCURACY OF TEST - COMPARE TO GOLD STANDARD What is the usefulness of the test in various groups and subgroups of pts? TESTS ARE RARELY 100% ACCURATE EXPERIMENTAL TEST THEY MUST BE COMPARED AGAINST THE GOLD STANDARD RESULTS OF GOLD STANDARD TEST TOTALS DISEASE PRESENT DISEASE NOT PRESENT TEST POSITIVE TRUE (+) a FALSE (+) b a+b TEST NEGATIVE FALSE (-) c TRUE (-) d c+d a+c b+d TOTALS a+b+c+d ACCURACY OF TEST - COMPARE TO GOLD STANDARD What is the usefulness of the test in various groups and subgroups of pts? TESTS ARE RARELY 100% ACCURATE EXPERIMENTAL TEST THEY MUST BE COMPARED AGAINST THE GOLD STANDARD TEST POSITIVE RESULTS OF GOLD STANDARD TEST TOTALS DISEASE PRESENT DISEASE NOT PRESENT TRUE (+) a FALSE (+) b a+b TRUE (-) d c+d SENSITIVITY TEST NEGATIVE FALSE (-) c SPECIFICITY TOTALS a+c b+d a+b+c+d SENSITIVITY AND SPECIFICITY SENSITIVITY = PATIENT (+) TEST (+) Probability that patient WITH disease will have ABNORMAL result (instead of False Negative) SPECIFICITY = PATIENT (-) TEST (-) Probability that patient WITHOUT disease will have NORMAL result (instead of False Positive) OVERALL DISCRIMINATION OF TESTS High SENSITIVITY = low number false negatives High SPECIFICITY = low number of false positives Best accuracy if both factors are close to 100% SENSITIVITY = a / (a + c) PATIENT (+) TEST (+) SPECIFICITY = d / (b + d) PATIENT (-) TEST (-) POSITIVE PREDICTIVE VALUE = a / (a + b) If pt tests (+), what is the likelihood s/he has the disease? NEGATIVE PREDICTIVE VALUE = d / (c + d) If pt tests (-), what is the likelihood s/he does NOT have the disease? PREVALENCE = (a + c) / (a + b + c + d) ACCURACY = (a + d) / (a + b + c + d) Proportion of results that correctly identify pts with and without disease (True + and True - as proportion of all results) LIKELIHOOD RATIO = sensitivity / (1 - specificity) How likely is it that + result accurately indicates disease, and - result no disease? LIKELIHOOD RATIO (LR) Because Sensitivity and Specificity are NOT always 100% How likely is it that + result accurately indicates disease, and - result no disease? LIKELIHOOD RATIO FOR A POSITIVE RESULT (LR+) Probability of (+) result in diseased subject divided by Probability of (+) result in a healthy subject - or worded differently - Sensitivity divided by 100% - Specificity LIKELIHOOD RATIO FOR A NEGATIVE RESULT (LR-) 100% - Sensitivity divided by Specificity DISCRIMINATION = ZERO IF LR = 1 EVALUATING STUDY RESULTS Example: Mortality rates in 4444 pts x 5.4 trial years: 11.5% Placebo 8.2% Medicine RRR 29% (Relative Risk Reduction) ARR 3.3% (Absolute Risk Reduction) NNT 30 (Number needed to treat for 5.4 years to save 1 life QALY = QUALITY ADJUSTED LIFE YEAR QUALITY RATING NOT specific for disease or treatment! Value rating - subject to different values of patients, physician, community • Patient-based • Economy-based - cost-utility/cost-effectiveness analysis Compares outcomes of conditions or intervention(s) • State of health - vs -Time spent in it QUALY: QUALITY ADJUSTED LIFE YEAR CHRONIC MEDIOCRITY PERFECT HEALTH 10 9 8 7 6 5 4 3 2 1 2 3 4 5 6 7 8 9 10 10 9 8 7 6 5 4 3 2 1 3 4 5 6 7 8 9 10 5-yrTREATMENT COMPARISON DETERIORATING HEALTH 9 8 7 6 5 4 3 2 1 0 2 10 8 Chemo&Rad 6 4 Radiation only 2 Chemo only 0 2 3 4 5 6 7 8 9 10 1 2 3 4 5 TEST RESULTS: VARIABILITY FACT: Study results may vary. Group too small Not representative of larger group May be discovered or identified through study Etc. Age, sex, race, condition, culture, etc. Compliancy issues (patient and physician!) TEST RESULTS: VARIABILITY FACT: Variability may or may not be significant Group too small Not representative of larger group May be discovered or identified through study Etc. Age, sex, race, condition, culture, etc. Compliancy issues (patient and physician!) TEST RESULTS: VARIABILITY Obviously faulty studies should be eliminated. Group too small Not representative of larger group May be discovered or identified through study Etc. Age, sex, race, condition, culture, etc. Compliancy issues (patient and physician!) TEST RESULTS: VARIABILITY Some variability should be expected in the rest. Group too small Not representative of larger group May be discovered or identified through study Etc. Age, sex, race, condition, culture, etc. Compliancy issues (patient and physician!) TEST RESULTS: VARIABILITY Some factors are completely unexpected. Group too small Not representative of larger group May be discovered or identified through study Etc. Age, sex, race, condition, culture, etc. Compliancy issues (patient and physician!) The statistics allow us to distinguish between and variability due to PROBABILITY Statistically significant Results are measurable and predictable Affected by sample size (1 in 20 is less convincing than 1 in 10,000) WARNING PROBABILITY should NOT be confused with CHANCE! CHANCE No statistical significance Random, unpredictable PROBABILITY A Study in Probability… QUESTION #1: What percentage of patients will develop diarrhea while taking Antibiotic A? QUESTION #2: Will the results be the same, better or worse on Antibiotic B? QUESTION #1: What percentage of patients will develop diarrhea while taking Antibiotic A? 50 50 50 50 50 50 50 50 50 50 50 50 50 20 study groups 50 50 50 50 50 pts each study 50 50 50 1000 patients total QUESTION #1: What percentage of patients will develop diarrhea while taking Antibiotic A? NUMBER OF STUDIES Conduct studies Organize results PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 8 10 12 14 16% IDENTIFY STATISTICALLY SIGNIFICANT RESULTS NUMBER OF STUDIES The Bell Curve PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 8 10 12 14 16% MODE NUMBER OF STUDIES Most COMMON result = PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 8 10 12 14 16% MEDIAN NUMBER OF STUDIES The CENTER of distribution = PERCENTAGE OF PATIENTS WITH DIARRHEA 4% 6 8 10 12 14 16% DETERMINE RESULTS OF STUDY NUMBER OF STUDIES MODE (most COMMON result) = 10% MEDIAN (the CENTER of distribution) = 10% PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 8 10 12 14 16% CONCLUSION NUMBER OF STUDIES “10% of patients will develop diarrhea while taking Antibiotic A.” PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 8 10 12 14 16% Wait… What about the other 15 study groups? NUMBER OF STUDIES You can’t just ignore them! PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 8 10 12 14 16 Or can you? Wait… What about the other 15 study groups? You can’t just ignore them! 15 groups x 50 per group = 750 patients (75%!) PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 8 10 12 14 16 Or can you? Wait… What about the other 15 study groups? You can’t just ignore them! Studies must account for ALL patients PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 8 10 12 14 16 Or can you? Wait… What about the other 15 study groups? NUMBER OF STUDIES You can’t just ignore them! Results should not be ignored, but STATISTICAL SIGNIFICANCE may be questioned. PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 8 10 12 14 16 Or can you? NUMBER OF STUDIES So, how is STATISTICAL SIGNIFICANCE determined? My head is starting to feel heavy… PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 8 10 12 14 16 STATISTICAL SIGNIFICANCE PROBABILITY is determined by it. CHANCE is not related to it at all! How is it determined? Let’s use our study on “Antibiotic A” as the example 20 groups were tested. Only 1 of 20 groups landed at each end of the Bell Curve…. NUMBER OF STUDIES WHY? SAMPLE VARIATION? or CHANCE? PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 8 10 12 14 16% NUMBER OF STUDIES It is tempting to say, “There is a 1 in 20 chance that other patients will land in these categories.” But that would NOT be a correct statement! PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 8 10 12 14 16% NUMBER OF STUDIES It is tempting to say, “There is a 1 in 20 chance that other patients will land in these categories.” Why? Because CHANCE can not be used to predict future results! PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 8 10 12 14 16% CHANCE is based on RANDOM possibility. Example: THE COIN TOSS Coins tossed: 20 “Heads” “Tails” 17 3 (85%) (15%) Statistical Significance: ZERO! The next coin toss will still produce a random result! Random results can not be used to calculate Statistical Probability. So instead of measuring “chance”… “There is a 1 in 20 chance that patients will land in one of these two categories.” 1 in 20 chance 1 in 20 chance PERCENTAGE OF PATIENTS WITH DIARRHEA 4% 6 8 10 12 14 16% We need to determine the PROBABILITY! “There is a 5% probability that patients will land in one of these two categories.” 1 in 20 chance 5% Translates into probability PERCENTAGE OF PATIENTS WITH DIARRHEA 4% 6 8 10 12 14 16% The results now look like this: There is a 5% probability that 4% of patients will develop diarrhea on Antibiotic A. There is a 5% probability that 16%of patients will develop diarrhea on Antibiotic A. PERCENTAGE OF PATIENTS WITH DIARRHEA 4% 6 8 10 12 14 16% And now… Let’s abbreviate it some more! p = 0.05 DECIMEL Probability = 5% 1 in 20 chance FRACTION PERCENTAGE PERCENTAGE OF PATIENTS WITH DIARRHEA 4% 6 8 10 12 14 16% …by changing “% probability” to the “p value” p = 0.05 DECIMEL Probability = 5% 1 in 20 chance FRACTION PERCENTAGE PERCENTAGE OF PATIENTS WITH DIARRHEA 4% 6 8 10 12 14 16% The “p value” is statistically important! p = 0.05 DECIMEL Probability = 5% 1 in 20 chance FRACTION PERCENTAGE PERCENTAGE OF PATIENTS WITH DIARRHEA 4% 6 8 10 12 14 16% It determines statistical PROBABILITY. p = 0.05 “p value” Probability = 5% 1 in 20 “chance” 4% 6 8 10 12 14 16% PROBABILITY vs CHANCE NUMBER OF STUDIES …but PROBABILITY is very important! It tells us the likelihood that something will happen. So, CHANCE has ZERO significance PERCENTAGE OF PATIENTS WITH DIARRHEA 4% 6 8 10 12 14 16% OUR PROBABILITY STATEMENT “There is a 5% probability that our study patients will fall into either of these categories.” p = 0.05 p = 0.05 PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 8 10 12 14 16% THAT IS A LOW PROBABILITY! Anything less than 5% (p= 0.05) MAY be due to chance. p = 0.05 p = 0.05 PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 8 10 12 14 16% THAT IS A LOW PROBABILITY! And anything less than 1% (p= 0.01) is MOST LIKELY due to chance! p = 0.01 4 6 8 10 12 14 16% p = 0.01 THAT IS A LOW PROBABILITY! Anything less than 5% (p= 0.05) MAY be due to chance. Anything less than 1% (p= 0.01) is MOST LIKELY due to chance. p = 0.05 p = 0.01 p = 0.05 4 6 8 10 12 14 16% p = 0.01 But when compared to another study… (p= 0.05) becomes VERY SIGNIFICANT And (p= 0.01) becomes HIGHLY SIGNIFICANT! 4 6 8 10 12 14 16 18% But when compared to another study… (p= 0.05) becomes VERY SIGNIFICANT And (p= 0.01) becomes HIGHLY SIGNIFICANT! 4 6 8 10 12 14 16 18% NUMBER OF STUDIES Antibiotic A PERCENTAGE OF PATIENTS WITH DIARRHEA 4% 6 8 10 12 14 16 18% NUMBER OF STUDIES Antibiotic B PERCENTAGE OF PATIENTS WITH DIARRHEA 4% 6 8 10 12 14 16 18% DIFFERENCE = STATISTICALLY SIGNIFICANT (p= 0.05) becomes VERY SIGNIFICANT And (p= 0.01) becomes HIGHLY SIGNIFICANT! 4 6 8 10 12 14 16 18% The P value Measures Probability How often is this finding expected to occur? Determines Statistical Significance What is the likelihood these findings are TRUE or FALSE? Do the comparative findings show a significant difference? Meaningful ranges p >0.05 Not significant p <0.05 Statistically SIGNIFICANT p <0.01 HIGHLY SIGNIFICANT! Does probability provide PROOF? NO! We could be misled by it. The sample size is very important when determining probability! SAMPLE SIZE and PROBABILITY EXAMPLE: 100 pieces of fruit are in a bin: APPLES and ORANGES You close your eyes and pick 10 of them: Question: Does your sample accurately represent what is in the bin? Answer: No! Larger samples provide a closer approximation of the populations they represent... But the only way to get 100% proof is to examine “all of the fruit in the bin!” The P value Meaningful ranges p >0.05 Not significant p <0.05 Statistically SIGNIFICANT* p <0.01 HIGHLY SIGNIFICANT!** *Significance only means that CHANCE is an unlikely explanation for the results LIMITATION The p value determines LIKELIHOOD… Not proof! CAUTION Statistical significance does not necessarily imply any clinical significance! EXAMPLE: Looking through a pinhole will improve vision in most people… But would this be an appropriate treatment for your myopic patients? (Key Topics in EBM ) MISCELLANEOUS STUFF THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process PATIENT Question or Problem PHYSICIAN INFORMATION (The Three Major Components of EBM) PATIENT PHYSICIAN INFORMATION PATIENT PATIENT “A METHODOLOGICAL MINEFIELD” PATIENT “A METHODOLOGICAL Difficult time Personal MINEFIELD” understanding priorities may background conflict with information yours PHYSICIAN INFORMATION PATIENT Recognize: Needs Choices Preferences Values Socioeconomic concerns CONFLICT? SEPARATE THE ISSUES! Respect the personal priorities of the patient PHYSICIAN Help the patient to negotiate a decision on intervention, treatment Help the patient to understand and interpret available information INFORMATION PATIENT And then help the patient pull it all together again PATIENT PHYSICIAN INFORMATION KEY POINTS PARADIGM SHIFT OLD: Doctor had authority (despite the pile of unread journals!) NEW: Current Best Evidence leads medical practice but it MUST be individually applied THE INDIVIDUAL PATIENT Every patient is different. Treat YOURS and not others The “ideal” course of action is not necessarily best for THIS patient. EBM + Psychosocial factors = THIS patient should be advised to take THIS therapy at THIS point in time. THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process Evaluate INFORMATION Adequate resources? Ease or Difficulty of finding and getting desired information? Costs? INTERVENTION Patient response or acceptance? Ease or Difficulty of Application? Clinical outcomes? EBM PROCESS EFFECT ON PRACTICE Will this particular experience change our thinking or practice? SELF EVALUATION How did we do? (Question, Search, Appraise, Apply) How could we improve our own EBM performance? EBM: PROS, CONS and LIMITATIONS PROS Clinicians update knowledge base routinely Improved understanding of research methods Physician becomes more critical in use of data Increased confidence in management decisions Increased computer literacy, data search technology Better reading habits Provides framework for group problem solving, team generated practice Transforms weakness or paucity of knowledge into positive change OK to be uncertain OK to be skeptical OK to be flexible Integrates medical education, research and clinical expertise Can be learned by non-clinicians – other HCWs, patient groups, purchasers, etc. Allows us to keep up with our better-educated patients! Increased contribution of junior MDs Increased patient benefit Better communication with patients re: rationale of management decisions Promotes better and more appropriate use of limited resources May reduce costs or medical care or practice by eliminating outdated or unnecessary factors Can be learned at any stage of physician’s career CONS Time consuming Information overload Time to learn and practice Time may be needed for team conferencing, planning and review Takes $$$ to establish resource infrastructure – library, office, etc. computers, peripherals Internet costs Programs, software information, CD-ROMS Subscription costs – online and paper resources May increase cost of care (but hopefully offset by elimination of unnecessary medical interventions, tests, journals, etc. – plus save time in getting proper intervention) Online references made to unavailable journals or references Exposes gaps in the evidence (but provides ideas for researchers!) Requires computer skills (but can be done with minimal computer literacy and skill) May expose your current practice as obsolete or dangerous (loss of authority and respect) LIMITATIONS Lack of evidence (shortage of studies) Difficulty applying evidence to care of a particular patient Barriers to the practice of high quality medicine Lack of skills (search, appraise, etc.) (foster development of new skills!) Lack of time to learn and practice EBM (promotes lifelong learning thru better focus) Lack of physician resources for instant access to evidence (EBM has worldwide applicability) RESTRICTED AVAILABILITY OF LAB TESTS NON-TEXTBOOK CASE co morbidity, additional risk factors AFFORDABILITY (MD & PT)“I can’t afford to practice EBM.” Language barriers – available evidence may be unreadable, should be included Physician attitude: Can be the greatest limitation! “It decreases the importance of my clinical expertise” (that’s a necessary component!) “It only applies to those involved in research.” (promotes cooperation among multiple physicians) “It ignores patient values and preferences.” “It’s just another cookbook approach to medicine.” “It’s a poorly disguised way to cut medical costs.” (cost of care may actually increase) “It’s a way to ration care and resources.” (Provides better utilization of avail resources) DISAGREEMENT Pt’s comfort, choice, acceptance, values preferences Vs MD’s recommendations DOES RISK OR SIDE EFFECTS OF TREATMENT OUTWEIGHT THE BENEFITS? The unanswered question… “DOES EBM REALLY MAKE A DIFFERENCE?” Effect of practicing EBM on patient outcome is actually unknown – no studies done EBM good based on population studies: (ie: Pts who rec’d ___ generally fare better than those who don’t) EBM IN DEVELOPING COUNTRIES LIMITED RESOURCES May help to eliminate unnecessary or poor quality screening tests (ie: resting EKG to screen for CAD = high false negative and false positive rates) LIMITED DRUG REGULATION Approval for drug marketing easy - promotes insurgence of new drugs for questionable indications, limited effectiveness, false claims, inflated prices based on ad response (include “more expensive is better”) EBM IN DEVELOPING COUNTRIES LIMITED CAPACITY FOR CME Drug companies - may sponsor meetings that are little more than captive marketing sessions or biased education sessions (drug education vs promo) Result may be push for more expensive, less effective treatments (ie push for CCB’s over BB’s) - calc channel blockers over Beta Blockers EBM IN DEVELOPING COUNTRIES LIMITED ACCESS TO LITERATURE DATABASES Desktop computer with CD ROM reader and modem ($900) Electricity 1 yr subscription to MedLine on CD ROM (?500) Internet connection $25/mt Convince administrators of expense: Publicly cite how searches help with lectures, research and patient care management decisions Get equipment from drug companies (usually strings attached) EBM IN DEVELOPING COUNTRIES LIMITED ACCESS TO ADEQUATE LIBRARY FACIILITIES ALMOST INEVITABLE IN DEVELOPING COUNTRIES Identify resources via search, but then unable to retrieve articles! A top EBM practitioner (Philippines) recommends: 1. Top 3 medical libraries in your country 2. Multinational drug company libraries 3. Friends and colleagues - including in other countries EBM IN DEVELOPING COUNTRIES QUESTIONABLE APPLICABILITY OF ARTICLES RETRIEVED Article describes a treatment that worked in one country, but seems impossible in yours Check… • • • • • Are there pathophysiologic differences? Will patient differences diminish the treatment response? Patient compliance issues? Provider compliance issues? Co-morbid conditions which will alter the benefits or risks? EBM IN DEVELOPING COUNTRIES OBSTACLES TO TEACHING OR LEARNING EBM Your Hospital or Institution does not reimburse for time spent on Continuing Medical Education programs The standard 5-day workshop would be far too costly to provide or attend! Need to learn the basics - computer skills, etc. TRY THESE! Combine efforts to learn more and practice EBM with handful of colleagues (small group learning) Ask about basis for information provided by drug reps, medical supply companies, etc. It will prompt them to provide you with on the spot teaching and better information, too! EBM LIBRARY BASIC REQUIREMENTS Convenient – easy access at point of contact with patient if possible Current – Up to date information Electronic Database – Should be included • Online • CD-ROM ELECTRONIC DATABASES Evidence-Based Medicine Reviews (EBMR) – from Ovid (ovid.com) - combines Cochrane, Best evidence, Evidence Based Mental health, EB Nursing, Cancerlit, healthstar, AIDSline, Medline, and journal links (Described by one EBM specialist as “the best”) Cochrane Library – “Gold Standard” for systematic reviews Best Evidence Medline – world’s largest, free resource – over 10 million references PERSONNEL Medical Librarian Informatics Specialist “We can learn a great deal about current best information sources from librarians and other experts in medical informatics, and should seek hands-on training from them as an essential part of our clinical training.” (ch 2 p29-30 – Blue circled 2) PRINTED RESOURCES TEXTBOOKS most obsolete! Some updated yearly, plus heavy references and scientific evidence for support Clinical Evidence (BMJ Publishing Group & ACP – 1999present) Evidence-Based On Call (http//cebm.jr.ox.uk/eboc/eboc.html) Up To Date (General medicine, CD format, Medline abstracts used for evidence) Scientific American Medicine – limited references from Medline, Harrisons JOURNALS Traditional Journals subject to author submissions specialists need to read and evaluate may subscribe to services that send articles of interest to your specialty timely, instant information at time of publication Ex: NEJM, Clinical Nephrology, etc. Evidence Based journals selects best studies from multiple journals of interest, summarizes best evidence Good for use by generalists Lag time from original publication: 3-6 months Ex: Evidence Based Medicine, Evidence Based Nursing, Evidence Based CV Medicine, etc. SPECIAL RESOURCES WHO Blue trunk Hinari PATIENT RESOURCES Medical treatments www.nlm.nih.gov/medlineplus Medical guidelines www.guideline.gov THE NEXT LEVEL: ADVANCED EBM SUMMARIZE AND STORE INFORMATION Future reference SHARING INFO Local Colleagues Author paper TEACHING New skills or treatments EBM practices OTHER APPLICATIONS Care of the individual patient Team protocols Hospital or practice guidelines EBM in Medical Education Message to medical educators from Trisha Greenhalgh, MD, co-author of Evidence Based Health Care Workbook: “An important challenge for medical educators… is to recognize that the competent student (and clinician!) is one who knows how to cope with an immense and rapidly changing body of knowledge and not one who excels in recalling the traditional or memorizing the ephemeral. The deans of medical and nursing schools must develop an infrastructure that allows problem-based, self-directed learning methods to develop within the didactic, lecturebased curricula, which have seen no fundamental changes for two centuries or more.” ADVANCED EBM: ADVANCED APPLICATIONS APPLY METHODS TO… Care of the individual patient Team protocols Hospital or practice guidelines Continued Learning: problem-based approach Teaching SELF-DIRECTED LEARNING JAMA Series of User Guides “Clinical Epidemiology: A Basic Science for Clinical Medicine” Week-long workshops On-the-job learning (in your own practice) EVIDENCE BASED MEDICINE A new approach to clinical care and research Developed and presented by Judy Tarselli, RN Dubai, UAE Karachi, Pakistan October 2003 Organized by NKF cyberNephrology University of Alberta, Canada www.cyberNephrology.org Special thanks to our sponsors at Janssen-Cilag of Dubai EVIDENCE BASED MEDICINE A new approach to clinical care and research Developed and presented by Judy Tarselli, RN Dubai, UAE Karachi, Pakistan October 2003 Organized by NKF cyberNephrology University of Alberta, Canada www.cyberNephrology.org Special thanks to our sponsors at Janssen-Cilag of Dubai