Epidemiology of Chronic Diseases
Class 08/23/2021
Section 1.1
Epidemiology
- is the study of the distribution and determinants of “health-related” states or events
(including disease), and the application of this study to the control of diseases and other
health problems
- The study of how disease is distributed in populations and factors
Causes of death
- 1900
o Pneumonia and flu
o TB
o Digestive disease
o Heart disease
- 2015
o Heart disease
o Cancer
o Lung disease
o Stroke
John Snow
- Father of epidemiology
Objectives
1. To identify the etiology disease
a. What increases/decreases your risk for a particular disease
b. Ultimate purpose is to reduce or eliminate exposure to factors, we can develop a
basis for prevention programs
2. To determine the extent of the disease in the community
a. What is the burden of the disease?
i. Ex: More than 1/3 of U.S. adults have obesity
b. Question is critical for planning health services and facilities for training future
HCPs
3. The study of the natural history and prognosis of disease
a. Determining a disease baseline natural history allows health scientists to test the
effectiveness of newly developed modes of intervention and treatment
4. To evaluate both existing and newly developed preventative and therapeutic measures
and modes of health care delivery
a. Does encouraging universal self-breast examination lead to decreased number of
cancer deaths?
5. To provide the foundation for the developing public policy relating to environmental
problems, genetic issues and other considerations regarding disease prevention and
health promotion
10 Great Public Health Achievements in the 20th Century
 Immunizations
 Motor-vehicle safety
 Workplace safety
 Control of infectious diseases
 Declines in deaths from heart disease and stroke
 Safer and healthier foods
 Healthier mothers and babies
 Family planning and widespread availability of cancer
 Fluoridation of drinking water
 Tobacco as a health hazard
Section 1.2
Model for Prevention
1. Primary prevention
 Preventing the initial development of a disease
o Immunizations
o School/classroom-wide systems for all students, staff, and settings
o Health promotion
o Specific protection
 Patient is in predisease stage of natural history
o Goal of prevention is to reduce or eliminate risk factors, increase
protective factors, and prevent pathologic process from occurring
 Health Promotion
o For individuals with no known risk factors
o Nonmedical efforts: lifestyle, nutrition, environments, improvement in
society
o Infectious disease: clean water, sanitary disposal of waste, control
vectors that spread disease, limit crowding, hygienic housing / working
environments
 Specific Protection
o For individuals with known risk factors, specific disease or injury
1. Immunizations, pharmacological treatment, protective devices /
equipment, water fluoridation
2. Secondary prevention
 Early detection of existing disease to reduce severity and complications
o Screening for cancer
o Specialized group
o Systems for students with high-risk behavior
o Case finding
o Treatment
1. For diagnosed disease / injury
2. More effective at this stage in the course of disease process
 Patient is latent / asymptomatic stage of natural history; disease / injury is
detectable but asymptomatic
o Goal of prevention is to interrupt natural course of disease before
becoming symptomatic and reduce risk factors
3. Tertiary prevention
 Reducing the impact of disease
o Rehabilitation for stroke
o Specialized
o Individualized
o Systems for students with high-risk
o Disability limitation
 Patient is in symptomatic stage of natural history
o Goal of prevention is to reduce or interrupt complications / impairment
/ disability resulting from symptomatic disease; prevent worsening of
condition
 Limitation of disability
o Initial care for early symptomatic disease: medical or surgical
interventions in addition to primary prevention
 Rehabilitation
o Subsequent care for advanced symptomatic disease: identify methods
to limit physical and social disability, educate
Population-based vs High-risk approach to prevention
- Population based approach
o A preventative measure is widely applied to an entire population
- High-risk approach
o May be more expensive and is often more invasive or inconvenient
- Population based approaches are considered public health approaches, whereas high
risk approaches ae considered those things that require clinical action
Class 8/30/2021
Lecture 2
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Epidemiology is often described as the basic science of public health
o A quantitative discipline that relies on a working knowledge of probability,
statistics, and sound research methods
o Method of casual reasoning based on developing and testing hypotheses
Distribution
o Epidemiology is concerned with the frequency and pattern of health events in a
population
o Frequency – refers not only to the number of health events (# of cases of
meningitis or diabetes), but also to the relation of that number to the size of the
population
o Pattern – refers to the occurrence of the health-related events by time, place,
and person.
 Time – annual, seasonal, weekly
 Place – geographic variation, urban / rural differences, location of work
sites or schools
Determinants
o Determinant: any factor, whether event, characteristic, or other definable
entity, that brings about a change in a health condition or other defined
characteristic
Application
o Epidemiology is not just the “study of” health in a population; also involves
applying the knowledge gained by the studies to community-based practice
*The first step in epidemiology often relies on descriptive data
 Are these differences real? Are the data comparable? Why have the differences
occurred? Are they environmental differences? Are there differences in people?
Endemic: the habitual presence of a disease within a given geographic area. May also refer to a
usual occurrence of a given disease within such an area
 Malaria in tropical environments
Epidemic: the occurrence in a community of region of a group of illness of similar nature,
clearly in excess of normal expectancy, and derived from common or from a propagated source
 Ebola outbreaks in the Democratic Republic of Congo
 Opioid deaths
Pandemic: a worldwide epidemic
 Swine flu cases
Epidemiologic observation
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Ignaz Semmelweis – Childbed fever
o 19th century – mortality rates from childbed fever were 25%
o Semmelweis concluded that physicians and medical students were carrying
infection from autopsy room to patients
o Conclusion was reluctantly accepted because of the medical community’s
implication in transmitting the agent responsible for childbed fever
o Bed fever was recognized later recognized to be a strep infection
o Hand-washing is now universally accepted
 Edward Jenner – Smallpox
o Smallpox epidemics
 Killed 300-500 million people in the 20th century
o Variolation – inoculated people would not be reinfected
o Those with cowpox, did not get smallpox
o Jenner used cowpox studies to make a smallpox vaccination
o Jenner is the father of immunology
 John Snow – Cholera
o Many people died of cholera who lived within a few blocks of the broad street
pump in London
o William Farr believed cholera was spread by miasmatic theory
 Miasma – a cloud that clung low on the surface of the earth
 Theory was supported because those lived at lower elevation got
cholera more often
*Absence of biological knowledge about pathogenesis should not be a hindrance or an excuse
for not implementing effective preventive services
 Cigarette smoking and lung cancer
Lecture 3
*Ventral Tegmental Area
 Causes addiction
o Develops tolerance
*Chronic diseases have been referred to as chronic illnesses, noncommunicable diseases, and
degenerative diseases
 Generally characterized by uncertain etiology, multiple risk factors, long latency period,
prolonged course of illness, noncontagious origin, functional impairment or disability,
and incurability
 Chronic disease – a disease that persists for a long time, lasting 3 months or more
 Chronic disease continuum ... over the life course
o Upstream social and economic determinants
o Individual behaviors
o Chronic conditions
o Chronic disease
o Disability and death
 Heart Disease
o Heart disease and stroke kills more than 859k Americans a year – 1/3 of all
deaths
o Costs healthcare system $199 billion and causing $131 billion in lost productivity
on the job
 Cancer
o More than 1.6 million people are diagnosed with cancer in the U.S., almost 600k
die from it
o Second leading cause of death
o Cost of cancer continues to rise
 Diabetes
o More than 34.2 million Americans have diabetes and another 88 million adults in
the U.S. have prediabetes
 Prediabetes places people at risk for DM 2
o Can cause heart disease, kidney failure, and blindness
o $327 billion in medical costs – 2017
 Obesity
o A disease and a risk factor
o Affects almost 1 in 5 children and 1 in 3 adults
o Places people at risk for chronic diseases
 Heart disease, diabetes, some cancers
o Costs $147 billion a year
 Leading causes of death
o Heart disease
o Cancer
o Lower respiratory disease
o Unintentional injuries
o Stroke
o Alzheimers
o Diabetes
o Pneumonia and influenza
o Kidney disease
o Suicide
*Risk Factors for Chronic Disease
 Tobacco use and environmental tobacco smoke
 Alcohol use
 High cholesterol
 High BP
 Diet
 Physical inactivity
 Obesity
 Stress
 Occupation
 Pollution
 Low socioeconomic status
Aging and Chronic Disease Burden
 Two views of aging
o Failure of success – perspective predicts exploding healthcare costs and dour
plights for the growing population of elderly who are faced with longer lives, but
lower quality existence during the extended years
o Fries hypothesis – he and his colleagues suggested that the maximum life span
has limits
 Proportion of people who will live to very old ages will not substantially
increase
Goals of Chronic Disease Prevention
1. Reduce the incidence of disease
2. Delay the onset of disease and disability
3. Alleviate the severity of disease
4. Improve the health-related quality and duration of the individual’s life
Health Promotion
 Primary prevention
 Secondary prevention
 Tertiary prevention
Class 09/13/2021
Lecture 4
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Healthcare costs are exploding due to an aging population
Percent of adults who reported delaying or going without care due to cost
o Delayed
 Insured 6%
 Uninsured 23%
o Did not get care
 Insured 4%
 Uninsured 20%
o Yes to either
 Insured 7%
 Uninsured 27%
Chronic diseases consume over 75-80% of the 2 trillion dollars spent on healthcare in
the U.S.
o Heart disease, cancer, and diabetes responsible for 7/10 deaths among
Americans each year
4.2
Epidemiologic surveillance: is the ongoing and systematic collection, analysis, and
interpretation of health data in the process of describing and monitoring a health event
 Epidemiologic surveillance system is needed to monitor trends and disease control
o To identify groups of people who are at risk of developing chronic disease or
who experience fewer benefits from interventions
o To measure the effect of program interventions
o To identify newly emerging chronic diseases
Epidemiologic Surveillance and Measures
 Two approaches that attempt to combine monitoring data on the incidence of, and
morbidity and mortality from diseases, uses the # of years of life lost from premature
death and the loss of health from disease and disability
o Quality-adjusted life year (QALY): often used in cost-effective analyses
o Disability-adjusted life year (DALY):
Class 09/27/2021
Lecture 7.1
Measures of Mortality
 If we wish to address the risk of dying, we must deal with rates
Mortality Rate
 Annual Mortality Rate (Crude Rate)
o Population at midyear is used as an approximation
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o Annual mortality rate for all causes (per 1,000 population)
o Total # of deaths from all causes in 1 year / # of persons in the population at
midyear x 1,000
Specified Mortality Rate
Disease-specific / Cause-specific Rate
o Places a restriction on a rate by specifying diagnosis, thus limiting the rate, to
deaths from a certain disease.
o Example: Lung cancer
 Annual mortality rate from lung cancer (per x population)
 (# of deaths from lung cancer in one year / # of persons in the population
at midyear) x per population
Age-specified mortality rate
Lecture 7.2
Comparing Mortality
 Important use of mortality data is to compare two or more populations
 Age is the single most important predictor of mortality
Lecture 8.1
Measures of Disease Frequency – Disease Impact
 Disease impact can be measured by examining the frequency of
o Mortality (Death)
o Morbidity (Sickness)
 Measures of Death
o Annual mortality
o Case-fatality
o Proportionate mortality
o Years of potential life lost
 Measures of Sickness
o Disability adjusted life year