Impact of Sustained Remission on the Risk of Serious Infection in Patients With Rheumatoid Arthritis

Objective. This retrospective analysis examined how sustained remission impacted risk of serious infections in patients with rheumatoid arthritis (RA) enrolled in a clinical registry. Methods. Inclusion criteria included RA diagnosis, age >= 18 years, and >= 2 Clinical Disease Activity Index (CDAI) scores followed by a followup visit. Index date was the second of 2 visits in which a patient had sustained remission (CDAI <= 2.8), low disease activity (LDA; 2.8 < CDAI <= 10), or moderate-to-high disease activity (MHDA; CDAI >10). Followup extended from the index date until first serious infection (requiring intravenous antibiotics or hospitalization) or last followup visit. The crude incidence rate (IR) per 100 patient-years for serious infections was calculated for the sustained remission, LDA, and MHDA groups. The multivariable-adjusted incidence rate ratio (IRR) (adjusted for age, sex, and prednisone dose) compared serious infection rates across disease activity groups. Results. Most patients were female (>70%); mean age was approximately 60 years. The crude IR (95% confidence interval [95% CI]) per 100 patient-years for serious infections was 1.03 (0.85-1.26) in the sustained remission group (n = 3,355), 1.92 (1.68-2.19) in the sustained LDA group (n = 3,912), and 2.51 (2.23-2.82) in the sustained MHDA group (n = 5,062). Compared to sustained remission, the serious infection rate was higher in sustained LDA (adjusted IRR 1.69 [95% CI 1.32-2.15]). Compared to sustained LDA, the serious infection rate was higher in sustained MHDA (adjusted IRR 1.30 [95% CI 1.09-1.56]). Conclusion. In this study, lower RA disease activity was associated with lower serious infection rates. This finding may motivate patients and health care providers to strive for remission rather than only LDA.