Predictors of Drug Retention and Survival Rate of bDMARDs in Rheumatoid Arthritis: A Four-Year Real-Life Tunisian Experience.

Introduction: This study aims to investigate the efficacy and tolerance of biologic disease-modifying anti-rheumatic drug (bDMARDs) in the current management of rheumatoid arthritis (RA) by identifying the retention time and survival rate of bDMARDs.

Materials and methods: We conducted a retrospective cohort study including Tunisian patients initiating bDMARD treatment between 2016 and 2018 whose data were collected from the National Health Insurance Fund (NHIF). The NHIF is the national office which organises and centralises patients under bDMARDs from all over the country. Retention and survival rate of bDMARDs at 48 months were analysed using Kaplan-Meier survival curves and compared using the log-rank test. Survival factor analysis was performed using Cox regression.

Results: Three hundred seventy-four patients, aged 55.5±12.5years [20-90], (87.2%women), were included. The mean duration of RA was 11.7±6.7 years [2-41]. The mean disease activity score (DAS)28 at initiation of the first bDMARD was 6.01±0.89 [5.37-6.5]. This first bDMARD induced low disease activity (LDA) in 55% of cases. Remission was observed in 28% of patients. The highest LDA and remission rates were observed with Tocilizumab (70.8% and 33.3% of cases, respectively). LDA and remission were achieved within a mean of 45 weeks [26-88] and 72 weeks [31-117] respectively. The 48-month first-line survival rate was 55.9%. Retention time was 41.7 months, 95%CI [39.47-43.91]. Presence of rheumatoid factors, co-prescription of methotrexate, and good initial therapeutic response were factors influencing better survival of bDMARDs (p<0.01). Glucocorticoid use predicted poorer survival (p<10-3). The first bDMARD was interrupted in 39% of cases. Ineffectiveness was the most common cause of treatment cessation (52.7%).

Conclusion: This real-life study of the Tunisian population allowed us to establish the factors that can influence the survival and retention rates of bDMARDs.