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.
Prepaid health plan in northern California.
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.
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.
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.