Background/Purpose: With the increasingly widespread use of biological agents (BA), a thorough knowledge of their long-term behavior in clinical practice is fundamental. The purpose of our study was to assess and compare the long-term survival of Biological Agents (BA) in elderly patients with Rheumatoid Arthritis (RA) in clinical practice. Factors associated to discontinuation were also investigated. 

Methods: Observational longitudinal study from 1999 to 2013 was conducted. RA patients followed in outpatient clinic at Hospital Clínico San Carlos, which started BA treatment after 65 years of age, were included. Primary outcome: BA (Etanercept; Infliximab; Adalimumab; Rituximab; and other BA [including Golimumab, Certolizumab, Abatacept and Tozilizumab]) discontinuation due to: adverse drug reaction (ADR), inefficacy, and other causes. Covariables: sociodemographic, clinical and therapy.  Incidence rates of discontinuation (IR) per 100 patient-years were estimated using survival techniques with their respective 95% confidence interval [95% CI]. Comparison between BA discontinuation rates and other associated factors were run by Cox regression models.  

Results: We included 286 courses of BA therapy in 146 patients (604 patient-years). Of these, 78% were women with a mean age at diagnosis of 66.5 ± 7 years and a median time to the start of the first BA of 6 ± 4 years. Adalimumab (27.3%), followed by Infliximab (22.4%), Etanercept (21.3%), and Rituximab (19.2%) were the most frequently used. Treatment was suspended in 199 cases (IR: 33 [28.6 -37.8]), 21.7% due to inefficacy (IR: 10.2 [8-13.5]), 39% to ADRs (IR: 18.4 [15.2- 22.1]), 2.8% to patient choice and 2.8% to improvement. In the first year of therapy 60% continued on BA, and after ten years, the retention rate didn´t exceed 5%. The crude IR of discontinuation was higher for Rituximab (IR: 39.2 [28-54]) compared to TNF- antagonists. In the multivariate analysis, after adjusting with calendar time, age and sex, we did not find differences between Adalimumab, Etanercept, Infliximab and Rituximab. Concomitant therapy with Disease Modifying Antirheumatic Drugs or corticoids, functional loss, positive anti–citrullinated protein antibodies and specific comorbidities were independent factors associated to discontinuation. 

Conclusion: After several years of BA treatment in clinical practice, the survival in our cohort was low, mainly as a result of ADRs and inefficacy. We did not find any statistical differences between Adalimumab, Etanercept, Infliximab and Rituximab discontinuation rate. But we have found other clinical and therapy factors that modify their survival. This study contributes to increasing knowledge of long-term survival of these drugs in RA patients over 65 years and in real life conditions.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/long-term-survival-of-biological-therapy-in-rheumatoid-arthritis-elderly-patients-in-clinical-practice/