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.
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.
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.
Use of combination therapy has remained unchanged over time despite the publication of high-quality data supporting its efficacy over anti-TNF monotherapy.