ABSTRACT: Background:Crohn's disease (CD) is associated with major health services utilization and costs. Between 2012 and 2015, ustekinumab was used off-label in Quebec, Canada for treatment of refractory CD. Aims:We assessed the direct medical cost of adult CD patients in the 1-year pre- and 1-year postustekinumab initiation. Methods:Data were obtained from the provincial administrative databases. CD patients dispensed subcutaneous ustekinumab in 2012 to 2014 were followed for 1 year from the date of initiation (index-date). Kaplan Meier plots were used to display time to ustekinumab discontinuation and factors associated with discontinuation were identified using multivariate Cox regression models. Direct medical costs and 95% confidence interval (CI) of gastrointestinal-related health services were calculated for the 1-year pre- and 1-year post-index-date. Results:Thirty-four CD patients (mean age ± standard deviation, 44 ± 14 years, 59% women and 41% with low income) were included. Of these, 14 (41%) discontinued ustekinumab during the postperiod. Discontinuation was less likely among older patients: hazard ratio (95% CI) per 5-year age increase, 0.77 (0.61 to 0.96). The total $CAN direct medical cost (mean, 95% CI) was higher in the post- versus preperiod: $1,681,239 ($49,448; $42,265 to $57,160) versus $880,060 ($25,884; $20,391 to 31,596), while the total costs of GI-related health services were similar: $250,206 ($7359, $3536 to $11,674), versus $213,446 ($6278, $3609 to $9423). Conclusion:In patients with severe refractory CD on off-label ustekinumab, approximately 60% remained on treatment beyond 1 year. The cost of gastrointestinal services did not increase during that year as compared to that of the year preceding ustekinumab use.