A Population-Based Study of Combination vs Monotherapy of Anti-TNF in Persons with IBD

Abstract

Background: Few data exist about the utilization of combination therapy (anti-tumor necrosis factor [anti-TNF] plus immunosuppressives) in clinical practice. We assessed the prevalence and predictors of combination therapy use vs anti-TNF monotherapy in inflammatory bowel disease (IBD) in the Canadian province of Manitoba. Methods: All 23 prescribers of anti-TNF medications for IBD in Manitoba facilitated chart review of their comprehensive lists of adult anti-TNF patients from 2005 to 2015. Subjects were stratified by year of first anti-TNF exposure. Patient, disease, and prescriber factors influencing combination therapy use were explored. Results: A total of 774 patients met inclusion criteria. Seventy-one point one percent had Crohn's disease (CD), 28.3% had ulcerative colitis (UC), and 0.6% had IBD unclassified; 45.3% received combination therapy, with no difference between CD and UC. Crohn's disease subjects receiving combination therapy were more likely to have penetrating or perianal disease (56.9% vs 42.8%; P = 0.001) and less likely to have had previous IBD-related surgeries (36.2% vs 46.2%; P = 0.02). The median age at diagnosis and at anti-TNF initiation was lower among combination therapy users. Adalimumab users were as likely as infliximab users to receive combination therapy but persisted with treatment for a shorter time. The proportion of new anti-TNF users receiving combination therapy did not change over time (P = 0.43). There was substantial variation in combination therapy use between prescribers (P = 0.002). The most frequently encountered reasons for avoiding combination therapy were previous intolerance or ineffectiveness of immunosuppressive monotherapy. Conclusion: Use of combination therapy has remained unchanged over time despite the publication of high-quality data supporting its efficacy over anti-TNF monotherapy.