Long-term use of biologic agents does not increase the risk of serious infections in elderly patients with rheumatoid arthritis

This study aimed to determine whether the long-term use of biologic agents increases serious infections in elderly patients with rheumatoid arthritis (RA) and to determine the risk factors of serious infections in biologics-treated elderly RA patients. We retrospectively analyzed the incidence rate of serious infections that required hospitalization between biologics-treated and non-biologic disease-modifying antirheumatic drug (DMARD)-treated elderly RA patients (aged over 65 years). We examined the risk factors for serious infections in biologics-treated elderly RA patients. We found that, during a 3-year observation period, the incidence rate of serious infections was not significantly different between biologics-treated and non-biologic DMARD-treated elderly RA patients [8.0 (95% CI 4.7-13.5) and 6.3 (95% CI 4.1-9.5) events per 100 person-years of follow-up, respectively, P = 0.78]. The time to the first serious infection did not significantly differ between the two groups by the analysis of the Kaplan-Meier curves, either (P = 0.46). We then found that prednisolone doses alone were significantly associated with serious infections in biologics-treated elderly RA patients. Furthermore, we found that prednisolone at 1-4 mg/day was associated with serious infections in biologics-treated patients, but not non-biologic DMARD-treated patients. On the other hand, prednisolone at greater than 5 mg/day was associated with serious infections in both biologics-treated and non-biologics-treated patients. We show that there is not a significant difference between the incidence of serious infections between biologics group and non-biologics group in elderly RA patients (≧65 years) and that even very low-dose glucocorticoid use (prednisolone 1-4 mg/day) is a risk factor for serious infections in biologics-treated elderly RA patients.