Is background methotrexate advantageous in extending TNF inhibitor drug survival in elderly patients with rheumatoid arthritis? An analysis of the British Society for Rheumatology Biologics Register

OBJECTIVE: To evaluate drug survival with monotherapy compared with combination therapy with MTX in RA older adults. METHODS: Patients from the British Society for Rheumatology Biologics Register, a prospective observational cohort, who were biologic naïve and commencing their first TNF inhibitors (TNFi) were included. The cohort was stratified according to age: <75 and ≥75. Cox-proportional hazards models compared the risk of TNFi discontinuation from (i) any-cause, (ii) inefficacy and (iii) adverse events, between patients prescribed TNFi-monotherapy compared with TNFi MTX combination. RESULTS: The analysis included 15 700 patients. Ninety-five percent were <75 years old. Comorbidity burden and disease activity were higher in the ≥75 cohort. Fifty-two percent of patients discontinued TNFi therapy during the follow-up period. Persistence with therapy was higher in the <75 cohort. Patients receiving TNFi monotherapy were more likely to discontinue compared with patients receiving concomitant MTX [hazard rate 1.12 (1.06–1.18) P <0.001]. This finding only held true in patients <75 [hazard rate (HR) 1.11 (1.05–1.17) vs ≥75 [HR 1.13 (0.90–1.41)]. Examining TNFi discontinuation by cause revealed patients ≥75 receiving TNFi monotherapy were less likely to discontinue TNFi due to inefficacy [HR 0.66 (0.43–0.99) P=0.04] and more likely to discontinue therapy from adverse events [HR 1.41(1.02–1.96) P =0.04]. These results were supported by the multivariate adjustment in complete case and imputed analyses. CONCLUSION: TNFi monotherapy is associated with increased treatment failure. In older adults, the disadvantage of TNFi monotherapy on drug survival is no longer seen. Patients ≥75 have fewer discontinuations due to inefficacy than adverse events compared with younger patients. This likely reflects greater disposition to toxicity but perhaps also a decline in immunogenicity associated with immunosenescence.