[Analysis on the efficacy of ustekinumab in the patients with isolated perianal Crohn disease].

To analyze the efficacy of ustekinumab (UST) in the patients with isolated perianal Crohn disease (ipCD). ipCD patients who received UST therapy in the Second Affiliated Hospital of Wenzhou Medical University between January 2021 and September 2025 were retrospectively recruited. Each patient received the first dose of UST (6 mg/kg) for intravenous induction, followed by the same dose of intravenous UST every 8 weeks for maintenance treatment. At week 16, the fistula clinical response was evaluated based on perianal disease activity index (PDAI) (a decline of more than 50% in PDAI compared with week 0). Follow-up was conducted until week 40, at week 40, the fistula clinical remission was assessed based on PDAI (PDAI score≤4 scores). The radiologic outcome events of perianal fistula were evaluated based on pelvic MRI data and Van Assche index, and the fistula radiologic response consisted of healing and partial response. A total of 16 ipCD patients were included, all of whom were male, with a diagnosed age of (31±6) years. At week 16 of UST therapy, the PDAI of 16 ipCD patients was decreased compared with week 0 [(7.3±2.5) vs (13.1±2.2) scores, P<0.001], and 10 patients obtained the fistula clinical response. At week 40, the average PDAI [(4.4±2.3) vs (13.1±2.2) scores, P<0.001], and the median Van Assche index [9 (8, 12) vs 16 (12, 16) scores, P=0.002] of 16 patients were lower compared with week 0; Eleven patients achieved the fistula clinical remission, and 10 patients obtained the fistula radiologic response. During 40-week follow-up, no adverse event related to UST treatment occurred in the ipCD patients. The UST therapy may demonstrate favorable clinical efficacy and safety in patients with ipCD.