Adalimumab persistence for inflammatory bowel disease in veteran and insured cohorts

Identify predictors of persistence with adalimumab (ADA) among veterans and privately insured patients with inflammatory bowel disease (IBD) in the United States.

Retrospective cohort study.

Patients with IBD taking ADA as their first biologic were identified from the Veterans Health Administration (VHA) database from 2009 to 2013 and the Truven Health MarketScan database from 2009 to 2012 with a 12-month follow-up. Persistence was defined as continued use 1 year after initiation. Adherence was assessed by calculating a medication possession ratio, which was dichotomized as greater than 0.86 or less than or equal to 0.86. Multivariable logistic regression was used to evaluate predictors of persistence.

There were 1030 patients in the VHA population compared with 3264 patients in the privately insured (MarketScan) cohort. In MarketScan, 1800 patients (55%) remained on ADA compared with 755 (73%) in the VHA cohort. In multivariable analysis, male sex (odds ratio [OR], 1.38; 95% CI, 1.16-1.63; P <.01), Crohn disease (OR, 1.27; 95% CI, 1.02-1.57; P = .03), greater adherence (OR, 1.83; 95% CI, 1.45-2.30; P <.01), and dose escalation (OR, 1.82; 95% CI, 1.42-2.33; P <.01) were associated with higher ADA persistence in the MarketScan cohort; narcotic use (OR, 0.71; 95% CI, 0.58-0.88; P <.01) and hospitalization or new steroid use after initiation (OR, 0.04; 95% CI, 0.03-0.05; P <.01) were associated with lower persistence. In the VHA cohort, only a hospitalization or new steroid use (OR, 0.50; 95% CI, 0.36-0.70; P <.01) was associated with lower persistence.

Despite being older and having more comorbidities, patients in the VHA, which is an integrated healthcare system, appear to be more likely to remain on ADA at 1 year than patients in the MarketScan database. Further studies of system differences are needed to understand the reasons behind this discrepancy.