OBJECTIVES: To study the influence of insurance reform on biologic drug persistence for Crohn’s disease (CD) treatment and CD-related health resource use (HRU) and the mediating effect of the maintenance treatment setting on that association.

METHODS: This was a cohort study based on inflammatory bowel disease (IBD) registry in Hangzhou city, China. Participants were CD patients who started Ustekinumab (UST) and receiving maintenance treatment during 2022. The exposure was the type of insurance, namely, the reformed medical insurance type with comparable inpatient and outpatient reimbursement policy for CD-related treatment; while the non-reformed insurance type getting reimbursed only under inpatient setting and have no outpatient reimbursement for CD treatment. Cox regression models generated hazard ratios (HR). Mediation analysis further accounted for the maintenance treatment setting.

RESULTS: A total of 133 patients were included: 65 (48.9%) from reformed insurance group and 68 (51.1%) from control group. Patients from the reformed insurance group incurred significantly less overall CD-related treatment cost: ¥10,640.53 vs. ¥16,430.7 with cost difference being ¥-5,790.17 (95%CI, -¥10,959.22, -¥621.11) and achieved improved persistence with a 72.75% lower risk of UST discontinuation (discontinuation risk, 7.69% vs. 25%; adjusted HR, 0.27; 95%CI, 0.10-0.74). Shifting UST maintenance therapy from inpatient to outpatient setting mediated a sizeable proportion of the aforementioned association between the insurance type and HRU outcomes, with full mediation on CD-related treatment expenditure, i.e. the natural indirect effect being ¥-10,125.09 (95% CI, -¥15,920.24, -¥4,329.94), and the natural direct effect being ¥4,334.92 (95% CI, -¥3,062.95, ¥11,732.80) and the proportion mediated on CD-related hospitalization number being 49.99% (95% CI, 18.76%, 81.21%).

CONCLUSIONS: Insurance reform by increasing the outpatient copayment rate for CD was found associated with reduction in overall CD-related treatment cost, which was fully mediated by maintenance treatment setting shift from inpatient to outpatient.