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

Objective: The objective of this study was to compare the efficacy and safety of rituximab in older vs younger patients with rheumatoid arthritis.

Methods: 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 ≥ 65 years (n = 91) with patients aged < 65 years (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.

Results: Drug survival was similar in the two age groups. The proportion of patients who remained taking rituximab over 2 years was 72% in those under aged 65 years vs 74% in those aged ≥ 65 years. 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).

Conclusions: Rituximab is a reasonable therapeutic option for older patients with rheumatoid arthritis although vigilance is needed with regard to the infection profile.

Trial Registration: ClinicalTrials.gov Identifier: NCT01581294.