Laboratory evaluation in the diagnosis of Lyme disease.

PURPOSE To provide a qualitative evaluation of the predictive value of the laboratory diagnosis of Lyme disease and to use the resultant data to formulate guidelines for clinical diagnosis. DATA SOURCES A MEDLINE search of English-language articles or articles with English-language abstracts published from 1982 to 1996. DATA EXTRACTION Sensitivity, specificity, and likelihood ratios were calculated, and a random-effects model was used to combine the proportions from the eligible studies. Prespecified criteria were used to determine which studies were eligible for analysis. DATA SYNTHESIS Laboratory testing in general is not clinically useful if the pretest probability of Lyme disease is less than 0.20 or greater than 0.80. When the pretest probability is 0.20 to 0.80, sequential testing with enzyme-linked immunosorbent assay and Western blot is the most accurate method for ruling in or ruling out the possibility of Lyme disease. CONCLUSIONS Laboratory testing is recommended only in patients whose pretest probability of Lyme disease is 0.20 to 0.80. If the pretest probability is less than 0.20, testing will result in more false-positive results than true-positive results; a negative test result in this situation effectively rules out the disease.