Association of Hydroxychloroquine Use with a Dose-Dependent Decrease in Mortality Risk in Patients with Elderly-Onset Rheumatoid Arthritis

Introduction Elderly-onset rheumatoid arthritis (EORA) is associated with an increased mortality risk; however, the effect of conventional synthetic, biologics or targeted synthetic disease-modifying anti-rheumatic drugs (csDMARDs, bDMARDs or tsDMARDs) on the EORA-specific mortality risk is unknown. In this study, we investigated the risk factors for all-cause mortality of patients with EORA. Methods Data of EORA patients diagnosed with RA at age > 60 years between January 2007 and June 2021 were extracted from the electronic health record of Taichung Veterans General Hospital, Taiwan. Multivariable Cox regression was used to calculate the hazard ratio (HR) and 95% confidence interval (CI). The survival of patients with EORA was analyzed by Kaplan-Meier method. Results Among the 980 EORA patients who were enrolled (survivors 852 and non-survivor 128), the significant mortality-associated risk factors [HR (95% CI)] included higher age (1.10 [1.07–1.12], p < 0.001), male sex (1.92 [1.22–3.00], p = 0.004), current smoker (2.31 [1.10–4.87], p = 0.027) and underlying malignancy (1.89 [1.20–2.97], p = 0.006). Hydroxychloroquine treatment conferred protection against mortality in patients with EORA (HR 0.30, 95% CI 0.14–0.64, p = 0.002). Patients with malignancy who did not receive hydroxychloroquine treatment had the highest mortality risk compared with their counterparts. Patients with a monthly cumulative dose of hydroxychloroquine dose < 1374.5 mg had the lowest survival rate compared to patients who received hydroxychloroquine 1374.5–5778.5 and ≥ 5778.5 mg. Conclusion Hydroxychloroquine treatment is associated with survival benefits in patients with EORA, and prospective studies are needed to validate the abovementioned findings.