Method: We combined data from Kaiser Permanente Northern California, Pharmaceutical Assistance Contract for the Elderly, Tennessee Medicaid and National Medicaid/Medicare, in a retrospective cohort (1998-2007). We identified patients with rheumatoid arthritis (RA); inflammatory bowel disease (IBD); and psoriasis (PsO), psoriatic arthritis (PsA) or ankylosing spondylitis (PsO-PsA-AS). The incidence of hospitalizations for serious infections was compared between initiators of TNF-α antagonists and alternate non-biologic DMARD regimens in disease specific-propensity score (PS) - matched cohorts using Cox regression models with non-biologics as reference. Baseline glucocorticoid use was categorized according to the estimated average daily dose of prednisone equivalents (none, >0-<5 (low dose), 5-10 (medium dose) and >10 mg (high dose)), and evaluated as a separate covariate.
Result: Among RA, IBD and PsO-PsA-AS patients, we identified 10602, 3219 and 1323 PS-matched pairs of episodes of TNF-α antagonist and alternate regimen use, respectively. Among RA patients, hospitalization rates of serious infections were 8.17 and 7.66 per 100 person-years, respectively (adjusted hazard ratio [aHR]: 1.09 (95% CI: 0.94-1.25)). Among IBD patients, the respective rates were 10.91 and 9.49 per 100 person-years (aHR: 1.14, (0.86-1.52)) whereas among PsO-PsA-AS patients, the respective rates were 5.41 and 5.19 per 100 person-years (aHR: 1.10, (0.80-1.53)). Among RA patients, infliximab was associated with a significant increase in the risk of serious infections compared with etanercept and adalimumab (aHRs: 1.26 (1.08-1.49) and 1.23 (1.02-1.48), respectively). For RA and PsO-PsA-AS, baseline glucocorticoid use was associated with a dose-dependent increase in risk of infections compared with no glucocorticoid use (for RA, aHRs: 1.39, 1.76 and 2.73; and for PsO-PsA-AS, aHRs: 1.36, 2.24 and 2.28 for low, medium and high doses, respectively).
Conclusion: In this large study consisting predominantly of older and low income patients with autoimmune diseases, initiation of TNF-α antagonists (as a group) was not associated with a significant increase in the risk of hospitalization for infections compared with alternate non-biologic regimens. Glucocorticoid use was associated with a dose-dependent increase in risk.
Disclosure: C. Grijalva, None; L. Chen, None; E. S. Delzell, Amgen, 2 ; J. Baddley, Abbott Immunology Pharmaceuticals, 5 ; T. Beukelman, None; K. L. Winthrop, Genentech, Abbott, and Amgen, 5 ; M. Griffin, None; L. Herrinton, Research grant, 2 ; L. Liu, None; P. Nourjah, None; N. M. Patkar, None; D. H. Solomon, Abbott Immunology Pharmaceuticals, 2, Amgen, 2, Corrona, 5, Bristol-Myers Squibb, 9 ; J. Lewis, Amgen, 5, Pfizer Inc, 5, Millenium Pharmaceuticals, 5, Allos Theraeutics, 5, Centocor, Inc., 2, Shire, 2, Takeda, 2 ; F. Xie, None; K. G. Saag, None; J. R. Curtis, Merck Pharmaceuticals, 2, Novartis Pharmaceutical Corporation, 2, Proctor & Gamble Pharmaceuticals, 2, Eli Lilly and Company, 2, Merck Pharmaceuticals, 5, Eli Lilly and Company, 5, Roche Pharmaceuticals, 5, Novartis Pharmaceutical Corporation, 5 .