TEST-TREATMENT STRATEGIES FOR PATIENTS SUSPECTED OF HAVING LYME-DISEASE - A COST-EFFECTIVENESS ANALYSIS

Purpose: To examine the cost-effectiveness of test-treatment strategie s for patients suspected of having Lyme disease. Data Sources: The med ical literature was searched for information on outcomes and costs. Ex pert opinion was sought for information on utilities. Study Selection: Articles that described patient population, diagnostic criteria, dose and duration of therapy, and criteria for assessment of outcomes. Dat a Extraction: The decision analysis evaluated the following strategies : 1) no testing-no treatment; 2) testing with enzyme-linked immunosorb ent assay (ELISA) followed by antibiotic treatment of patients with po sitive results; 3) two-step testing with ELISA followed by Western blo t and antibiotic treatment for patients with positive results on eithe r test; and 4) empirical antibiotic therapy. Three patient scenarios w ere considered: myalgic symptoms, rash resembling erythema migrans, an d recurrent oligoarticular inflammatory arthritis. Results were calcul ated as costs per quality-adjusted life-year arid were subjected to se nsitivity analysis. Adjustment was made for the diagnostic value of co mmon clinical features of Lyme disease. Data Synthesis: For myalgic sy mptoms without other features suggestive of Lyme disease, the no testi ng-no treatment strategy was most economically attractive (that is, ha d the most favorable cost-effectiveness ratio). For rash, empirical an tibiotic therapy was less costly and more effective than other strateg ies. For oligoarticular arthritis with a history of rash and tick bite , two-step testing was associated with the lowest cost-effectiveness r atio. Testing with ELISA and empirical antibiotic therapy cost an addi tional $880 000 and $34 000 per quality-adjusted life-year, respective ly. For oligoarticular arthritis with one or no other features suggest ive of Lyme disease, two-step testing was most economically attractive . Conclusions: Neither testing nor antibiotic treatment is cost-effect ive if the pretest probability of Lyme disease is low. Empirical antib iotic therapy is recommended if the pretest probability is high, and t wo-step testing is recommended if the pretest probability is intermedi ate.