Serious Infections in Patients with Autoimmune Diseases

Chicago—The risk of serious infection was not significantly increased in patients with autoimmune diseases initiating treatment with tumor necrosis factor (TNF) antagonists compared with those treated with nonbiologic disease regimens, even in older and low-income people, according to a study presented at the ACR meeting. The investigators retrospectively examined the incidence of serious infections in patients with autoimmune diseases during the first 12 months after initiation of TNF antagonists or nonbiologic regimens. Carlos Grijalva, MD, MPH, the study’s lead author and assistant professor in the department of preventive medicine at Vanderbilt University’s School of Medicine in Nashville, Tennessee, discussed the study in an oral abstract session. Results were simultaneously published online in the Journal of the American Medical Association [doi:10.1001/jama.2011.1692]. Despite the demonstrated efficacy of TNF antagonists to treat a number of autoimmune diseases, safety concerns persist and have not been adequately evaluated in the current evidence. Among the limitations of the current evidence is the inability to extrapolate outcomes to broader populations of patients who actually receive these agents, such as more vulnerable populations like the elderly and poor. To fill this gap, investigators used data from the national US Medicaid and Medicare databases (excluding Tennessee), Tennessee Medicaid, and Kaiser Permanente Northern California, New Jersey, and Pennsylvania Pharmaceutical Assistance Programs to identify patients with autoimmune diseases who were initiating selected medications. Patients were categorized into 3 mutually exclusive groups: those with rheumatoid arthritis (RA), inflammatory bowel disease (IBD), and psoriasis and spondyloarthropathies. Study medications were classified into 2 groups: TNF antagonists (infliximab, adalimumab, and etanercept) and comparator nonbiologic regimens that included leflunomide, sulfasalazine, or hydroxychloroquine after methotrexate for RA, azathioprine or mercaptopurine for IBD, and methotrexate, hydroxchloroquine, sulfasalazine, or leflunomide for psoriasis and spondyloarthropathies. Patients were excluded if they had ≥1 autoimmune disease, a disease other than those included in the 3 categories, or used a nonstudy regimen. Using these databases, the study cohorts included 10,484 with RA, 2323 with IBD, and 3215 with psoriasis and spondyloarthropathies matched pairs using comparator regimens and TNF antagonists. Serious infections were identified based on those that required hospitalization. Overall, 1172 serious infections were identified, among which the majority (53%) was due to pneumonia or skin and soft tissue infections. The study found no association between increased risk of serious infection and initiation of TNF antagonist among patients in any of the 3 categorized autoimmune disorders. The rate of serious infections in patients treated with TNF antagonists did not significantly differ from the rate for patients treated by the nonbiologic regimens for any of the patients in the 3 categories. The rate of serious infections in patients treated with TNF antagonists or comparator regimens was 8.16 and 7.78 per 100 person-years, respectively, for RA patients (adjusted hazard ratio [aHR], 1.05; 95% confidence interval [CI], 0.91-1.21); 10.91 and 9.60 per 100 person-years, respectively, for IBD patients (aHR, 1.10; 95% CI, 0.83-1.46); and 5.41 and 5.37, respectively, for patients with psoriasis and spondyloarthropathies (aHR, 1.05; 95% CI, 0.76-1.45). Dr. Grijalva added that the new information from this study, combined with the existing data, could be useful to inform decisions about the optimal treatment for patients with autoimmune diseases.