Disclosure: none Objective: ◦ To use a case-based approached to discuss wise use of laboratory tests in rheumatic diseases Methods—Accenting … Choosing Wisely, Cases, and Differential Diagnosis 2 Published simultaneously in 2002 in Annals of Internal Medicine, The Lancet and the European Journal of Internal Medicine Charter articulated 3 principles 1. Primacy of the patient 2. Autonomy of the patient 3. Social justice ◦ Includes aspiring to be good stewards of society’s resources 1. 2. 3. Don’t test ANA sub-serologies without a positive ANA and clinical suspicion of immune-mediated disease. Don’t test for Lyme disease as a cause of musculoskeletal symptoms without an exposure history and appropriate exam findings Don’t perform MRI of peripheral joints to routinely monitor inflammatory arthritis 4. 5. Don’t prescribe biologics for rheumatoid arthritis before a trial of methotrexate (or other conventional non-biologic DMARDs) Don’t routinely repeat DXA scans more often than once every two years 1. 2. Don’t do imaging for low back pain within the first 6 weeks, unless red flags are present Don’t use DEXA screening for osteoporosis in women < 65 or men < 70 with no risk factors. CC: 42 y.o. man with acute LBP HPI: Moved office 48 hrs ago Awoke with acute LBP; worse with activity, better with rest. Naprosyn helps some. ROS: No fever, weakness, bowel/bladder sxs PMH: negative Examination: VS normal; tenderness LB; neuro exam (-) What tests should you order? 7 Possible fracture ◦ ◦ ◦ ◦ Major trauma, minor trauma > age 50 Long-term corticosteroid use Osteoporosis Age > 70 Possible Tumor or Infection ◦ Age > 50, < 20 ◦ History of cancer, injection drug use,recent bacterial infection, constitutional symptoms, immunosuppression ◦ Pain when supine or at night 8 CC: 78 y.o woman with headache HPI: 2 months fatigue, malaise, 5 lb weight loss 1 month of intermittent dull headache PMH: hypertension, osteoarthritis ROS: occasional jaw pain Medications: HCTZ, acetaminophen PE: 36.8 145/83 84 pale Labs: Hct 32, WBC 6,700 Platelets 532k CMP-nl ESR 105 9 Ancient Methods: Westergren, Wintrobe Inexpensive Uses: ◦ Not diagnostic of any disease ◦ Supports diagnosis of GCA, PMR, Osteomyelitis ◦ Helpful in monitoring (GCA, PMR, RA, Osteomyelitis) 10 Influenced by concentration of [asymmetric particles] = fibrinogen Requires fresh sample Normal values <20 mm ◦ But affected by age (5/decade), gender, hematocrit, red cell morphology, many plasma proteins, medications (heparin) 12 Symptom (+) LR (-) LR Jaw claudication 4.2 (2.8-6.2) 0.72 (.57-.81) Diplopia Beaded TA Any TA abnl ESR abnl 3.4 (1.3-8.6) 4.6 (1.1-18.4) 2.0 (1.4-3) 1.1 (1-1.2) 0.95 (.91-.99) 0.93 (.88-.99) 0.53 (.38-.75) 0.2 (.08-.51) JAMA 2002;101:287-292 N Total GCA patients (1950-1998) 167 # with ESR < 50 mm/hr 18 (11%) # with ESR < 40 mm/hr 9 (5%) 1. Can the ESR be normal in GCA? Yes 2. Does a ESR > 100 have special significance? Maybe 3. In an older person with >100 ESR and no obvious disease other than GCA, what else should I consider? Multiple Myeloma 15 1. What gives false positives? Pregnancy, multiple myeloma, oral contraceptives, MGUS 2. What gives false negatives? Polymyositis. Cryoglobulinemia, congestive heart failure 16 1. Can the ESR be used as a screening test to determine if a patient with vague symptoms is sick? Not known! Only 31% of patients with gastric cancer have ESR > 20 2. What’s the maximum ESR a person can have? 200 – (2 x Hct) 3. Is CRP better than ESR? 17 CC: 19 y.o. AA woman polyarthralgia, fever HPI: 5 wks polyarthralgia, fever, malar rash, pleuritic chest pain, nocturia, ankle swelling FH: Mother had SLE PMH: negative Meds: ibuprofen PE: T=37.9, malar erythema, alopecia, edema Labs: Hct 32, WBC 2.7 Platelets 110k Creatinine 1.2 Albumin 3.2, Urine 3+ protein, RBC casts, BC/RPR What autoantibodies should you order? 18 What is a positive ANA? 1-10% of well people have ANA >1:80 20 of “sick” people have ANA>1:80 What is value of ANA? negative ANA excludes SLE; no value monitoring What autoantibodies are specific for SLE? ds-DNA antibodies 99% specific; sensitivity 50% anti-SM specific (95%); sensitivity 30% low Complement: specificity ~90%, sensitivity 50% 19 Disorder % (+) ANA SLE 99 RA 30-50 Fibromyalgia 20 Multiple Sclerosis 20 Thyroid disease 40 20 CC: 24 y.o. woman with polyarthritis HPI: 5 wks polyarthritis mcps, pips, wrists, knees 2 hrs morning stiffness; fatigue ROS: (-) fever, weight loss, rash, weakness, chest pain, back pain, travel, tick exposure, neuropathy FH: negative Meds: naproxen PE: polyarthritis; no nodules Labs: Hct 35, ESR 58, CMP/UA negative What autoantibodies should you order? 21 TEST Sensitivity RF 40-90% 40-90% 70-80% 85-95% Anti-CCP Specificity RF = rheumatoid factor Anti-CCP = anti-cyclic citrillinated peptide 22 Is a 26 year old day care worker with faint, diffuse rash? Is a 55 year old smoker with new clubbing? Is a 49 year old with large joint arthritis and red eye? Is 34 year injection drug user with recurrent purpura? 23 CC: 46 yo man oligoarthralgia, nasal stuffiness HPI: 3 months oligoarthralgia knees, shoulders nasal stuffiness, crusting, bleeding red eye, cough, fever, hearing loss left ear PMH: negative SH: no cocaine PE: scleritis, nasal crusting, otitis media, no joint effusion Labs: Hct 41, WBC 11k, Creatinine 1.6, urine 10-15 RBC’s; Chest CT: multiple nodules What autoantibodies should you order? 24 Pattern C-ANCA P-ANCA Antigen proteinase-3 myeloperoxidase Disease GPA MPA* Churg-Strauss Drug-induced GPA= granulomatosis with polyangiitis *MPA = microscopic polyangiitis Choosing wisely is part of professionalism Avoid ordering imaging for acute LBP unless red flags are present Most blood tests in rheumatology should be ordered when the probability of disease is intermediate Don’t test ANA sub-serologies without a positive ANA and clinical suspicion 29 < 1 mg/dl Normal Pregnancy Depression Obesity Gingivitis 1-10 mg/dl MI CTD >10 mg/dl bacterial INF vasculitis 30 Do IF first; confirm result with ELISA C-ANCA = anti-PR3 = GPA P-ANCA = anti-MPO = GPA, MPA etc “Atypical” ANCA = anti-Lactoferin, etc = IBD Cocaine, levamisole can cause vasculitis with positive C-ANCA, P-ANCA 31 C-Reactive Protein (CRP) is an acute phase protein whose concentration reflects level of inflammation Unaffected by age (?), gender, monoclonal antibodies; fresh sample not required Quantification is precise; wide range of clinically relevant values May be more sensitive than ESR in GCA, PMR 33 Disease GPA MPA Sensitivity 70-90% 70-90% Specificity 30-90%? 30-80% GPA= granulomatosis with polyangiitis *MPA = microscopic polyangiitis c-ANCA p-ANCA