Serological diagnostics of Lyme borreliosis: comparison of assays in twelve clinical laboratories in Northern Europe.

Lyme borreliosis (LB), caused by spirochetes belonging to the Borrelia burgdorferi sensu lato complex, is the most common tick-borne infection in Europe. Laboratory diagnosis of LB is mainly based on the patients' medical history, clinical signs and symptoms in combination with detection of Borrelia-specific antibodies where indirect enzyme-linked-immunosorbent assay (ELISA) is the most widely used technique. The objective of the study was to evaluate and compare the diagnostic accuracy (sensitivities and specificities) of serological tests that are currently in use for diagnosis of LB in clinical laboratories in Northern Europe, by use of a large serum panel. The panel consisted of 195 serum samples from well-characterized and classified patients under investigation for clinically suspected LB (n = 59) including patients with Lyme neuroborreliosis, Lyme arthritis, acrodermatitis chronica atrophicans, erythema migrans or other diseases (n = 112). A total of 201 serum samples from healthy blood donors were also included. The panel (396 serum samples altogether) was sent to 12 clinical laboratories (using five different ELISA methods) as blinded for group affiliation and the laboratories were asked to perform serological analysis according to their routine procedure. The results from the study demonstrated high diagnostic concordance between the laboratories using the same diagnostic assay and lower diagnostic concordance between laboratories using different diagnostic assays. For IgG, the results were in general rather homogenous and showed an average sensitivity of 88% (range 85-91%) compared to IgM which showed lower average sensitivity of 59% (range 50-67%) and more heterogeneous results between assays and laboratories.