Background and Importance Real world use of ustekinumab in inflammatory bowel disease (IBD) influence real costs of treatment.

Aim and Objectives To evaluate the effectiveness of ustekinumab in terms of persistence, doses dispensed and economic annual impact per patient in real-world clinical practice.

Material and Methods Retrospective review of patients diagnosed with IBD that started treatment with ustekinumab from 01/01/2018 to 06/30/2022. Follow-up was carried out until 06/30/2023.

Variables collected sex, weight, height, age, diagnosis, prior biologic or JAK-inhibitor(iJAK) therapies, time in treatment with ustekinumab, reason for discontinuation and cumulative dose dispensed during the follow-up period.

Outcome variables: persistence defined as percentage of patients that reached 12months treatment and median annual cost of treatment with ustekinumab. As dosing of ustekinumab in real-world practice is dynamic, cost of treatment on maintenance was evaluated using the number of doses dispensed. Theoretical cost was obtained from the dose provided in the drug file.

Data were collected from the electronic health and pharmacy dispensing record.

Statistical analysis Continuous variables were expressed as mean(SD) or median(Q1-Q3), and categorical variables as absolute and relative frequency. Statistical analysis was performed with R-commander_v.2.9.

Results Fifty-nine patients were included, 30(50.8%) men, 50(84.7%) Crohn`s disease, mean age 46(14.3) years, mean weight 67(14) kg and mean height 168(8.9) cm.

Patients treated with ustekinumab in first line were 10(17.0%), second line 24(40.6%) and 25(42.4%) other treatment lines.

Twelve months persistence of ustekinumab was 79.6%(n=47 patients). Reasons for discontinuation were 6(42.8%) secondary failure, 4(28.6%) primary failure, 2(14.4%) side effects, 2(14.2%) others. Median time on treatment was 16(RIC 31) months.

Median annual cumulative dose per patient was 783.5 mg (RIC 429), while theoretical annual dose was 585mg (dosage of 90mg/8weeks) and 387mg (dosage of 90mg/12weeks) representing a dose-escalation of 33% and 102% compared with the theorical dose respectively. Median annual cost per patient was 18102.€, while theoretical annual cost was 15027.3€ (90mg/8weks) and 9941€ (90mg/12weeks), which represents an increase of 20.4% and 82.1% respectively.

Conclusion and Relevance Ustekinumab was associated with a 12months persistence of 66%. Doses-escalation is common clinical practice in IBD with ustekinumab. Consequently, this has important implications for real costs.

Conflict of Interest No conflict of interest.