Diagnostic impact of routine Lyme serology in recent-onset arthritis: results from the ESPOIR cohort.

OBJECTIVES Lyme disease may be considered by rheumatologists in patients with recent-onset arthritis, even in the absence of suggestive symptoms. The aim of this study was to determine the diagnostic impact of routine Lyme serology in a French cohort of patients with recent-onset arthritis affecting at least 2 joints. METHODS We performed an ancillary study of a French prospective multicentre cohort established to monitor clinical, biological and radiographic data in patients with inflammatory arthritis in at least 2 joints, lasting for 6 weeks to 6 months. Borrelia IgM and IgG antibodies were sought routinely at baseline, using ELISA tests, independently from the physician's strategy for detecting a spirochetal infection. We recorded the proportion of patients with a final diagnosis of Lyme arthritis and evaluated the diagnostic performance of Lyme serology in this particular context. The clinical and biological characteristics of patients according to the Lyme serology results were analysed. RESULTS Of 810 patients, 657 (81.1%) were negative for IgM and IgG antibodies, 91 (11.2%) had only IgM antibodies, 49 (6%) had only IgG antibodies, and 13 (1.6%) had IgG and IgM antibodies. Thus, 7.6% had IgG positivity, consistent with exposure to Borrelia infection. IgG positivity was significantly more prevalent in the North and North-East regions of France (χ(2)=14.6, p<0.001). No patients received a definite diagnosis of Lyme arthritis. CONCLUSIONS This study does not support routine Lyme serological testing in patients with recent-onset inflammatory arthritis affecting more than 1 joint.