Clinical Utility of Common Serum Rheumatologic Tests -- American Family Physician

www.aafp.org/afp AMERICAN FAMILY PHYSICIAN 1073 negative test result. A positive result on a test with a high positive predictive value indicates that the patient probably has the disease in question. Similarly, a test with a high negative predictive value indicates that the patient with a negative test result most likely does not have the disease in question. Sensitivity and specificity are independent of disease prevalence, whereas predictive value is markedly affected by disease prevalence. For example, the predictive value of a positive rheumatologic test in patients with polyarthralgia is likely to be higher in a rheumatology practice than in a family physician’s office. This fact emphasizes the importance of limiting testing to patients with a reasonable pretest possibility of disease. As the pretest probability increases, so does the clinical utility of a given test.