Impact of adalimumab on work participation in rheumatoid arthritis: comparison of an open-label extension study and a registry-based control group

Background and objectives: Rheumatoid arthritis (RA) causes considerable disability and often results in loss of work capacity and productivity. This study evaluated the impact of adalimumab, a tumour necrosis factor antagonist with demonstrated efficacy in RA, on long-term employment. Methods: Data from an open-label extension study (DE033) of 486 RA patients receiving adalimumab monotherapy who previously did not respond to at least one disease-modifying antirheumatic drug (DMARD) and had baseline work status information were compared with data from 747 RA patients receiving DMARD treatment in a Norway-based longitudinal registry. Primary outcomes included the time patients continued working at least part time and the likelihood of stopping work. Secondary outcomes included American College of Rheumatology (ACR) and European League Against Rheumatism (EULAR) responses and disease remission. Outcomes were compared 6, 12 and 24 months after enrolment. Results: During a 24-month period, the 158 patients who received adalimumab and were working at baseline worked 7.32 months longer (95% CI 4.8 to 9.1) than did the 180 patients treated with DMARDs, controlling for differences in baseline characteristics. Regardless of baseline work status, patients receiving adalimumab worked 2.0 months longer (95% CI 1.3 to 2.6) and were significantly less likely to stop working than those receiving DMARDs (HR 0.36 ( 95% CI 20.30 to 0.42) for all patients and 0.36 (95% CI 0.15 to 0.85) for patients working at baseline, respectively). The patients who received adalimumab were also considerably more likely to achieve ACR responses and disease remission than DMARD-treated patients. Patients who achieved EULAR good response and remission were less likely to stop working, but this relationship was only seen in patients receiving DMARDs. Conclusions: Patients with RA who received adalimumab experienced considerably longer periods of work and continuous employment, and greater rates of clinical responses, than patients receiving DMARDs. The mechanism by which adalimumab decreases likelihood of stopping work seems to be different from that of DMARD treatment and independent of clinical responses.