Comorbidity burden and clinical characteristics of patients with difficult-to-control rheumatoid arthritis

Introduction Difficult-to-treat rheumatoid arthritis (RA) is a significant clinical problem despite no clear definition. We aimed to provide clinical characteristics and associated comorbidities of RA patients in relation to disease control. Methods RA characteristics and physician-recorded comorbidities were analyzed in a sample of 1937 RA patients. Patients treated for RA for 5.2 y (IQR, 2.1–11.3) were classified as difficult-to-control when presenting with DAS28-ESR > 3.2 despite previous use of at least 2 csDMARDs. A comparison of demographic and RA-related characteristics between difficult-to-treat and low disease activity patients (DAS28-ESR ≤ 3.2) was performed. Comorbidity burden was assessed by calculating Rheumatic Diseases Comorbidity Index (RDCI). Logistic regression model was constructed for difficult-to-control disease. Results Hypertension (46.9% (95%CI, 44.7–49.2)), coronary artery disease (CAD) (18.5% (95%CI, 16.8–20.3)), and diabetes (14.4% (95%CI, 12.9–16.0)) were the most prevalent conditions in RA patients. When compared with the adequate control group, difficult-to-control patients were increasingly burdened with hypertension (52.7% (95%CI, 47.5–57.8) vs. 42.0% (95%CI, 36.6–47.6); p = 0.006), cardiovascular diseases (24.2% (95%CI, 20.1–28.9) vs. 11.1% (95%CI, 8.0–15.1); p