Unincreased mortality of patients with early rheumatoid arthritis compared to the general population in the past two decades: results from a Japanese prospective observational cohort: IORRA

Abstract Background: The mortality of patients with rheumatoid arthritis (RA) has been reported to have reduced due to the improved treatment of RA in the last two decades. However, it has not yet been clarified whether the progress of RA treatment improves the prognosis of patients with early RA. We aimed to investigate the mortality rate of patients with early RA over the past two decades. Methods: Patients with RA who participated in the Institute of Rheumatology, Rheumatoid Arthritis (IORRA) cohort within two years of disease onset between 2001– 2012 were enrolled and classified into Group A (2001–2006) and B (2007–2012). The standardized mortality ratio (SMR) versus the Japanese general population and five-year survival rate were calculated. A multiple imputation method was employed for the sensitivity analysis of SMR. The five-year survival rates were evaluated using the Kaplan–Meier method. Results: Groups A and B had 1,609 and 1,608 patients, respectively, of which 167 (10.4%) and 178 (11.0%) patients were lost during follow-up, respectively. Overall, 47 and 45 deaths of patients were confirmed in Groups A and B, respectively. The SMR (95% confidence interval) for Groups A and B were 0.81 (0.59–1.08) and 0.78 (0.57–1.04), respectively, with the condition that all untraceable patients were alive for 5 years. Assuming that the mortality rate of patients lost to follow-up was twice as high as that of the general population, the SMR was 0.90 (0.68–1.19) for Group A and 0.92 (0.68–1.23) for Group B. The 5-year survival rates were 96.9% and 97.0% for groups A and B, respectively ( P =0.83). Conclusions: The 5-year mortality of patients with early RA has been comparable to that of the general Japanese population; the 5-year survival rate has been stable over the past two decades.