CC5-05: Comparative Safety of Infliximab and Etanercept on the Risk of Serious Infections – Does the Association Vary By Patient Characteristics?

摘要

Background/AimsInfliximab, a chimeric monoclonal anti-TNF? antibody, has been found to increase the risk of serious infections compared with the TNF receptor fusion protein etanercept in some studies. It is unclear whether the risk varies by patient characteristics. We conducted a study to address this question. MethodsWe identified members of Kaiser Permanente Northern California who initiated infliximab (n=793) or etanercept (n=2,692) in 1997-2007. Using a Cox model, we estimated the propensity score-adjusted hazard ratio (HR) and 95% confidence interval (CI) of serious infections requiring hospitalization or opportunistic infections comparing infliximab with etanercept following treatment initiation. We estimated the stratum-specific HRs by age (=65 years), sex, race/ethnicity (Non- Hispanic White, African-American, Hispanic, Asian American, Native American, and other/unknown), body mass index (=25 kg/m2), and smoking status (non, past, and current smokers); and performed likelihood ratio tests to examine whether the HR differed by these patient characteristics. ResultsThe crude incidence rate of serious infections per 100 person-years was 5.4 (95% CI: 3.8, 7.5) in patients =65 years during the first three months following treatment initiation. Compared with etanercept, the adjusted HR during this period was elevated for infliximab in patients =65 years (HR 0.94; 0.41, 2.13). The test for homogeneity was marginally statistically significant (p-value=0.06). Findings did not suggest that the HR varied by other patient characteristics examined. DiscussionAn increased risk of serious infections associated with infliximab relative to etanercept did not appear to be modified by patients' sex, race/ethnicity, body mass index, or smoking status. There was an indication that the increased risk might vary by age. Additional studies are warranted to verify or refute this finding.