By Wayne Kuznar
Chicago, IL—Patients who initiate treatment with tumor necrosis factor (TNF) inhibitors for autoimmune diseases are not as likely to develop serious infections as those who start treatment with nonbiologic drugs, according to a study presented at the 2011 American College of Rheumatology meeting.
In a retrospective cohort study comparing TNF inhibitors with nonbiologic therapies, Carlos G. Grijalva, MD, MPH, Assistant Professor of Preventive Medicine, Division of Pharmacoepidemiology, Vanderbilt University, Nashville, TN, and colleagues found the rate of serious infections to be approximately 8 per 100 person-years with each type of treatment.
Most previous safety studies of TNF inhibitors had small sample sizes, short follow-up periods, and grouped TNF inhibitors in a single category. The investigators used a multi-institution collaboration of 4 large databases (Kaiser Permanente Northern California, New Jersey and Pennsylvania Pharmaceutical Assistance programs, Tennessee Medicaid, and national Medicare/Medicaid), together known as the Safety Assessment of Biologic Therapies (SABER), to assemble cohorts of patients with rheumatoid arthritis (RA), inflammatory bowel disease (IBD), and psoriatic arthritis, and matched controls for each group.
The databases were examined for the incidence of hospitalization for serious infections. The sample included 10,484 comparator pairs with RA, 2323 pairs with IBD, and 3215 pairs with psoriasis and spondyloarthropathies. A propensity score matching analysis was used to control for potential confounders. Follow-up lasted for a maximum of 1 year.
A total of 1172 infections that required hospitalization occurred between 1998 and 2007, with 53% being pneumonia or skin and soft-tissue infections.
Among patients with RA who started treatment with a TNF inhibitor, the rate of serious infection requiring hospitalizations was 8.16 per 100 person-years, which was not significantly different from the rate of 7.78 per 100 person-years among patients with RA who started therapy with a regimen of a nonbiologic disease-modifying antirheumatic drug.
Differences in the rates of hospitalization for serious infections emerged between the TNF inhibitors. Among the patients with RA, the rate of serious infection with infliximab (Remicade) was 26% higher than for etanercept (Enbrel) and 23% higher than for adalimumab (Humira), commented Dr Grijalva.
Among patients with RA, baseline use of corticosteroids was associated with a dose-dependent increase in risk for infections, ranging from a 32% increase in risk with baseline dosages <5 mg daily to nearly triple the risk with dosages >10 mg daily. “The findings were consistent across diseases,” said Dr Grijalva.
Among patients with psoriasis or spondyloarthropathy, the risk of infections was higher for patients receiving glucocorticoid doses of 5 to 10 mg daily (hazard ratio [HR] 2.01; 95% confidence interval [CI], 1.08-3.73) and >10 mg daily (HR 2.77; 95% CI, 1.44-5.32) compared with no glucocorticoid use.
The data provide reassurance for patients and providers that TNF inhibitors did not increase the risk of serious infections when compared with other nonbiologic treatments, Dr Grijalva said.
In an editorial that accompanied the publication of the study (Grijalva CD, et al. JAMA. 2011;306:2331-2339), Will Dixon, PhD, of the University of Manchester, England, and David T. Felson, MD, MPH, of Boston University School of Medicine, wrote, “These intriguing findings need replication in other studies. Nevertheless, the report by Dr Grijalva et al raises important questions about the comparative safety of immunosuppressant and biologic therapy and may prompt a reevaluation of anti-TNF safety.”