TICK BITES AND LYME-DISEASE IN AN ENDEMIC SETTING - PROBLEMATIC USE OF SEROLOGIC TESTING AND PROPHYLACTIC ANTIBIOTIC-THERAPY

Context.-The use of serologic testing to diagnose Lyme disease (LD) is a source of controversy. Expert recommendations also discourage the r outine use of antibiotic therapy for prophylaxis of LD following tick bites, but the extent to which physicians in endemic areas have adopte d these recommendations is not known. Objective.-To assess the pattern of use of serologic testing and antibiotic therapy for tick bites and LD and associated charges for management in an endemic area. Design.- Active surveillance of patient-physician encounters for tick bites and LD. Setting.-Primary care practices on the Eastern Shore of Maryland. Patients.-Consecutive sample of 232 patients with tick bites, LD (def ined by physician diagnosis in medical record), and suspected LD (phys ician notation of possible, but not definite LD) seen in 1995. Main Ou tcome Measures.-Serologic testing for LD, test results, antibiotic the rapy, and direct costs of management. Results.-Surveillance identified 142 patients (61.2%) with diagnoses of tick bites, 40 patients (17.2% ) with LD, and 50 patients (21.6%) with suspected LD. Of the 142 patie nts seen for tick bites, 95 (67%) underwent serologic testing for LD. Of these, 93 patients had initial negative or equivocal results; 24 (2 6%) of the 93 had convalescent testing, with 1 seroconversion. Seventy -eight patients (55%) with a diagnosis of tick bite received antibioti c therapy. No patients with tick bite developed clinical LD. Serologic testing for LD was performed for 36 patients (90%) with a diagnosis o f LD and 46 patients (92%) with suspected LD. In most cases, antibioti cs were prescribed before serologic test results became available. Con valescent testing was not performed for 37 (86%) of the 43 patients wi th suspected LD who had initial negative or equivocal results. Of thes e 37 patients, 25 (68%) did not receive antibiotic therapy. Direct cha rges for treatment of these 232 patients totaled $47 595, one third of which was attributable to serologic testing. A total of 32% of direct charges were for patients with tick bites, 48% were for patients with LD, and 20% were for patients with suspected LD. Conclusions.-In this setting, most patients consulting physicians for tick bites received prophylactic antibiotic therapy of unproven efficacy and underwent unn ecessary, costly serologic testing. Despite almost universal use in th is study, serologic testing for LD did not appear to influence treatme nt of patients diagnosed as having LD.