Adverse drug events in rheumatoid arthritis and osteoarthritis ambulatory patients

We aimed to determine the prevalence and characteristics of adverse drug events (ADE) in rheumatoid arthritis (RA) and (osteoarthritis) OA patients.

A cross-sectional study at rheumatology clinics, was performed by random selection of RA and OA out-patients by a research pharmacist. All suspected ADEs occurring during the last hospital visit and the subjects were identified by retrospective chart review and direct patient interview. ADE characteristics, including causative drug groups, affected organ severity and patient outcomes, were recorded.

One hundred and forty-three patients consisting of 129 RA and 14 OA were recruited. The patients' mean ages were 54.3 ± 14.3 years and 121 (84.6%) patients were female. A total of 68 ADEs were detected in 51 patients. The prevalence and rate of ADE were 35.7% and 47.6 events per 100 patients, respectively. Thirty out of 68 ADEs (44.1%) were preventable. Disease-modifying anti-rheumatic drugs and non-steroidal anti-inflammatory drugs resulted in ADEs by 41 (59.4%) and 10 (14.5%) events, respectively. Common affected organs were skin, gastrointestinal tract and eyes which accounted for 20 (29.4%), 18 (26.5%) and eight events (11.6%), respectively. Continuation of the suspected drug was noted in 42 ADEs (61.8%), classified as severity level 1 and 2a-b, and 43 ADEs (63.2%) were completely or partially resolved during the study period.

ADEs are common in RA and OA patients with prevalence of 35.7%. High exposure to potentially harmful drugs might explain the higher rate of ADE in these patients.