Background: Several studies have proposed that the immunosenescence of elderly patients with Rheumatoid Arthritis (RA) in treatment with biological therapies could eliminate the need for concomitant immunosuppression with disease-modifying drugs (DMARDs), due to a probable lower production of anti-drug antibodies; however, the evidence is limited.

Objectives: To compare the characteristics of patients with RA who started a second biological agent, according to age groups. To analyse second biological agent survival and its relationship with DMARDs.

Methods: Retrospective, observational and longitudinal study. Patients with RA who started a second biologic between 2000 and 2019, who discontinued a first-line TNF inhibitor, were included. Demographic, clinical and analytical data were obtained. The sample was divided in 2 groups: <70 and ≥70 years old. A comparative analysis was performed. Kaplan-Meier curves and Log-rank were used to conduct the survival analysis.

Results: 156 patients were included. 83.3% were women, with a mean age at the beginning of second biological treatment of 54.64±13.54 years. 22 patients (14.1%) were ≥70 years. Comparative analysis is detailed in table 1: patients ≥70 years presented a longer time from diagnosis to the start of biological treatment, and a higher prevalence of hypertension and diabetes mellitus. The main cause of withdrawal in this group was adverse events (46.67%) while in younger patients was treatment failure (25.27% primary failure, 29.66% secondary failure). The most frequent biological agent in ≥70 years was Rituximab (27.26%) while in <70 years was Etanercept (26.12%). 126 patients (80.8%) had a DMARD associated. In both groups, Methotrexate was the most frequent (table 2). The second biological agent survival analysis showed that patients who received a DMARD presented a higher survival [77 months (55.50-98.55) vs. 51.53 months (41.67-61.40); p=0.023]. After conducting a survival analysis in patients whose withdrawal cause was treatment failure, DMARDs use was associated with an increased biological agent survival in patients <70 years [103.48 months (82.28-124.68) vs. 81.95 months (66.05-97.86); p=0.037]; but statistical differences were not found in patients ≥70 years [117.33 months (82.15-152.52) vs. 65.07 months (40.72-89.42); p=0.291].

Conclusion: DMARD concomitant treatment has been related to a higher second biological treatment survival. This beneficial effect was not observed in RA patients ≥70 years of age whose second biological agent withdrawal cause was failure. In this age group, withdrawal related to adverse events was more frequent.

References: [1]Kalden JR, Schulze-Koops H. Immunogenicity and loss of response to TNF inhibitors: implications for rheumatoid arthritis treatment. Nature reviews Rheumatology. 2017;13(12):707-718.

Disclosure of Interests: None declared