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Using Medicare claims data on 189,326 RA patients, researchers at the University of Alabama at Birmingham examined the rates of hospitalized infections in previously biologic-treated RA patients and compared rates in cohorts starting new treatment with etanercept, adalimumab, certolizumab, golimumab, infliximab, abatacept, rituximab or tocilizumab.
Among 31,801 new biologic starts, patients were treated with etanercept (12%), adalimumab (15.2%), certolizumab (5.9%), golimumab (4.4%), infliximab (12.4%), abatacept (28.9%), rituximab (14.8%), and tocilizumab (6.3%). Concomitant steroids were used in 54-66% of patients and methotrexate use was highest with infliximab (61%) and lowest with certolizumab (53%). The comorbidity risk was similar across groups.
Overall, 2,530 hospitalized infections were identified during the follow-up period (2006-2011), with incidence rates varying from 13.1 for abatacept to 18.7 for rituximab per 100 person-years. Compared with abatacept, the adjusted hazard ratios were significantly higher for etanercept (HR 1.24), infliximab (1.39) and rituximab (1.36). Rates of hospitalized infections were similar (not increased) for those taking adalimumab, certolizumab, golimumab, and tocilizumab, compared to abatacept. Mortality rates (5%) were the same for all groups.
RA patients who were previously treated with a biologic have an increased risk of hospitalized infections with the start of a new biologic, with a crude incidence rate of 15.3 (95% CI: 14.7-15.9) per 100 person-years. This number stands out against rates seen with biologic-naive patients. The historic rate of serious infections in RA (3-9/100PY) in the pre-biologic era and the serious infection rates reported for each biologic in the product label (2-6/100PY) are lower than that reported in this cohort.
While there was a 40% difference in relative risk between the agents reported herein, the absolute risk of hospitalized infection was modest; 5.6 per 100 person years at most. Yun and coworkers have shown that RA patients previously exposed to biologics had a significantly higher one-year risk of hospitalized infection when exposed to etanercept, infliximab and rituximab compared to abatacept.