Abstract

Background COBRA (for ‘COmbinatie therapie Bij Rheumatoide Artritis’) combination therapy is effective for the treatment of rheumatoid arthritis (RA), but long-term safety is unknown. This study evaluates survival, comorbidities and joint damage in the original COBRA trial cohort.

Methods In the COBRA trial, 155 patients with early RA were treated with sulfasalazine (SSZ) monotherapy (SSZ group) or a combination of step-down prednisolone, methotrexate (MTX) and SSZ (COBRA group). The current 11-year follow-up study of the COBRA trial invited all original patients and performed protocollised scrutiny of clinical records, questionnaires, physical examination, laboratory and imaging tests.

Results In all, 152 out of 155 patients yielded at least partial data. After a mean of 11 years follow-up, 18 (12%) patients had died, 6 COBRA patients and 12 SSZ patients, HR 0.57 (95% CI 0.21 to 1.52). Treatment for hypertension was significantly more prevalent in the COBRA group (p=0.02) with similar trends for diabetes and cataract. Conversely, hypercholesterolaemia, cancer and infection showed a trend in favour of COBRA. Other comorbidities such as cardiovascular disease and fractures appeared in similar frequency. Radiographic findings suggest as a minimum sustained benefit for COBRA therapy, that is, difference in joint damage but similar subsequent progression rates after 5 years. Imputation to compensate for selective dropout suggests increasing benefit for COBRA, that is, difference in yearly progression rates similar to that seen in the first 5 years of follow-up.

Conclusions After 11 years, initial COBRA combination therapy resulted in numerically lower mortality and similar prevalence of comorbidity compared with initial SSZ monotherapy. In addition, lower progression of joint damage suggests long-term disease modification.