The association between diabetes mellitus control and advanced anti-rheumatic treatment, among rheumatoid arthritis patients: A nation-wide based, retrospective, cohort study

Introduction: Diabetes Mellitus (DM) is a known risk factor for worse clinical outcomes among patient with Rheumatoid Arthritis (RA), yet the effect of glycemic control on RA treatment has not yet been investigated. Study objective: To examine the association between DM control and biologic or targeted synthetic Disease-Modifying Anti-Rheumatic Drug (b/tsDMARDs) use among RA patients. Methods: We conducted a retrospective population-based cohort study. RA patients were included if they had at least two recorded diagnoses of RA AND either one of the following: were Rheumatoid Factor (RF) or anti Cyclic Citrullinated Peptide (CCP) positive, OR purchased conventional synthetic DMARDs (csDMARDs) 1 year before 2nd documented diagnosis of RA. Patients were classified by median hemoglobin A1C% (HbA1c) during 12 months before the index date: managed DM (MDM) (HbA1c<8%) or unmanaged DM (UMDM) (HbA1c≥8%). The primary outcome was the proportion of patients prescribed a b/tsDMARDs within the first two years after the index date. Secondary outcomes included the number of b/tsDMARDs switches following the index date. Gradient Boosting Classifier was used for a comprehensive propensity score matching. Results: From a total of 3977 RA patients, 400 were selected for UMDM group and 800 for MDM group. In the UMDM group 12.25% of patients initiated b/tsDMARDs within two years from the index date, compared to 13.87% of MDM patients (OR 0.87, 95% CI 0.60–1.24, P=0.49). The mean number of b/tsDMARDs switches was not statistically significant between groups at 2 and 5 years. Conclusion: RA patients with UMDM, as compared with MDM, do not have higher odds of being prescribed b/tsDMARDs within the first two years after RA diagnosis.