Context.— The use of serologic testing to diagnose Lyme disease (LD) is a source
of controversy. Expert recommendations also discourage the routine use of
antibiotic therapy for prophylaxis of LD following tick bites, but the extent
to which physicians in endemic areas have adopted 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 (defined by physician
diagnosis in medical record), and suspected LD (physician notation of possible,
but not definite LD) seen in 1995.
Main Outcome Measures.— Serologic testing for LD, test results, antibiotic therapy, 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 patients seen for tick bites, 95 (67%) underwent serologic
testing for LD. Of these, 93 patients had initial negative or equivocal results;
24 (26%) of the 93 had convalescent testing, with 1 seroconversion. Seventy-eight
patients (55%) with a diagnosis of tick bite received antibiotic therapy.
No patients with tick bite developed clinical LD. Serologic testing for LD
was performed for 36 patients (90%) with a diagnosis of LD and 46 patients
(92%) with suspected LD. In most cases, antibiotics were prescribed before
serologic test results became available. Convalescent testing was not performed
for 37 (86%) of the 43 patients with suspected LD who had initial negative
or equivocal results. Of these 37 patients, 25 (68%) did not receive antibiotic
therapy. Direct charges for treatment of these 232 patients totaled $47595,
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
unnecessary, costly serologic testing. Despite almost universal use in this
study, serologic testing for LD did not appear to influence treatment of patients
diagnosed as having LD.