FRI0198 The risk of chronic q fever in rheumatoid arthritis patients with and without anti-tnf therapy

Background The Netherlands faced a large Q fever outbreak from 2007-2010, during which many individuals have been infected with Coxiella burnetii, the intracellular bacterium causing Q fever. Initial infection is often asymptomatic. Chronic Q fever, which develops in a minority of infected individuals (1-5%), presents months to years after primary infection, mostly as endocarditis or vascular infection. Immunosuppression, although not clearly defined, is a stated risk factor for chronic Q fever. Anti-TNF therapy is associated with increased risk of intracellular infections. Objectives To examine whether rheumatoid arthritis (RA) patients on anti-TNF therapy are at increased risk of development of chronic Q fever, compared to TNF-naive RA patients using disease modifying drugs (DMARDs). Methods RA patients, living in Q fever epidemic areas, were identified in rheumatology outpatient clinics in participating hospitals. We selected a cohort of patients on anti-TNF therapy (infliximab, etanercept, adalimumab) for at least three months during the epidemic and a cohort TNF-naive patients who were using DMARDs during the same period. Participants were screened for anti-C. burnetii antibodies, measuring IgG against C. burnetii phase I and II in serum. Patients with phase I and/or II IgG titres ≥1:32 were defined as seropositive, indicating previous exposure to C. burnetii. All seropositive individuals were referred for follow-up to the department of internal medicine. Chronic Q fever was diagnosed according to the Dutch guideline on chronic Q fever diagnostics,1 by a team of medical specialists. Results From December 2011 to July 2012, 361 patients on anti-TNF therapy and 398 TNF-naive patients participated. The anti-TNF treated patients more frequently used systemic prednisone (at least three months during the epidemic) (P < 0.001). Of patients on anti-TNF therapy, 60/361 (16.6%) were seropositive, compared to 56/398 (14.1%) of TNF-naive patients (P=0.35). Overall, 10/116 (8.6%) seropositive patients were diagnosed with chronic Q fever, of which 7/60 (11.7%) patients on anti-TNF therapy compared to 3/56 (5.4%) TNF-naive patients (P=0.33). Univariate analysis in seropositive patients identified higher age, the use of systemic prednisone, valvulopathy/prosthetic valve and aneurysm/vascular prosthesis as significant risk factors for chronic Q fever. Conclusions We did not find a significantly higher prevalence of chronic Q fever in patients on anti-TNF therapy compa