The use of serologic tests for Lyme disease in a prepaid health plan in California
C. Ley, C. Le, E. M. Olshen and A. L. Reingold
Epidemiology Program, School of Public Health, University of California, Berkeley 94720.
OBJECTIVE--To determine the reason(s) why serologic tests for Lyme disease
are performed, who initiates the test requests, and how the test results
are used in a clinical setting. DESIGN--Retrospective cohort.
SETTING--Prepaid health plan in northern California. PATIENTS--Consecutive
sample of 117 patients for whom at least one serologic test for Lyme
disease was performed during a 3-month period. MAIN OUTCOME
MEASURES--Reason for ordering and result of the serologic test,
differential diagnoses, and treatment. RESULTS--One of 117 patients had
antibodies to Borrelia burgdorferi. Fifty-six percent of test requests were
initiated by the physician and 35% by the patient. Of 66 tests ordered by
the physician, 20% were performed because of suspected early Lyme disease,
6% as follow-up of a tick bite, 2% to confirm a prior history of Lyme
disease, 14% as a workup for arthritis, and 60% as one of a battery of
laboratory tests for vague symptoms. Of 41 tests initiated by the patient,
51% were performed because of a history of a tick bite. The reasons for
ordering 10 tests were undetermined. CONCLUSION--Only 19% of all serologic
tests for Lyme disease were performed because the physician suspected Lyme
disease in the patient. Particularly in light of the low probability of
contracting Lyme disease in California, it appears that this serologic test
is being overused. Indiscriminate testing increases health care costs and
does not appear to affect treatment decisions. Education is needed
regarding the limitations of this serologic test.
