Adverse events in patients with ankylosing spondylitis treated with TNF inhibitors: a cross-sectional study

Background Although TNF inhibitors are well established in ankylosing spondylitis treatment, the majority of studies on TNF inhibitors safety have been performed in rheumatoid arthritis patients. Meanwhile, it seems that TNF inhibitors in ankylosing spondylitis may present a better safety profile than we thought. Objective The aim of our study was to retrospectively investigate the occurrence of adverse events in ankylosing spondylitis patients treated with TNF inhibitors. Setting A single referral center in Poland. Methods Detailed medical history of ankylosing spondylitis patients was obtained during the interview with the patient and by reviewing electronic medical records. Patients treated with TNF inhibitors and patients without TNF inhibitors treatment were compared. Main outcome measure The incidence of adverse events during the 3 months period before the interview. Results A total of 150 patients, 103 in the treatment group and 47 in the control group, were included in the study. There were no differences in the incidence of adverse events, serious adverse events, infections and opportunistic infections between both groups. However, in the treatment group, noninfectious adverse events were significantly less frequent than in control group (RR 0.39, 95% CI 0.23-0.66), with abdominal pain as the most common noninfectious adverse event (RR 0.20, 95% CI 0.07-0.63). The differences in incidence rates of specific infections were not significant, except acute infectious diarrhea which also was less frequent in patients treated with TNF inhibitors (RR 0.17, 95% CI 0.03-0.85). The female gender was significantly associated with any adverse event occurrence (OR 2.36, 95% CI 1.15-4.83). Conclusion TNF inhibitors show a good safety profile in ankylosing spondylitis patients.