Does Older Age have an Impact on Rituximab Efficacy and Safety? Results from the NOR-DMARD Register.

Abstract

The objective of this study was to compare the efficacy and safety of rituximab in older vs younger patients with rheumatoid arthritis. Data on 367 patients with rheumatoid arthritis treated with rituximab in the Norwegian Disease-Modifying Antirheumatic Drug (NOR-DMARD) register were analysed, comparing patients aged ≥ 65years (n = 91) with patients aged < 65years (n = 276). Drug survival was compared using a Kaplan-Meier analysis and Cox proportional hazard models. Disease activity, as assessed by the Disease Activity Score based on 28 joints and erythrocyte sedimentation rate (DAS28-ESR) and the Simplified Disease Activity Index, was analysed with linear mixed models. The occurrence of adverse events was analysed by quasi-Poisson regression models. Drug survival was similar in the two age groups. The proportion of patients who remained taking rituximab over 2years was 72% in those under aged 65years vs 74% in those aged ≥ 65years. No statistically significant association with age was found for drug survival in either the unadjusted (hazard ratio 1.13, p = 0.65) or adjusted Cox proportional hazard analyses for the model with DAS28-ESR as a confounder (effect size 1.11, p = 0.73). Models including the Simplified Disease Activity Index instead of DAS28-ESR yielded similar results. Age was furthermore not significantly associated with disease activity over time, although there was a tendency towards a poorer response in older patients. In the older age group, there was a higher incidence of pneumonia (107 vs 51 per 1000 patient-years) and other serious infections (142 vs 66 per 1000 patient-years). Rituximab is a reasonable therapeutic option for older patients with rheumatoid arthritis although vigilance is needed with regard to the infection profile. ClinicalTrials.gov Identifier: NCT01581294.