Abstract:Objective To evaluate the real -world clinical efficacy and safety of ustekinumab（UST）in biologic -na?ve patients with moderate -to-severe Crohn's disease（CD），providing evidence -based support for clinical treatment decision. Methods A retrospective study was conducted on 65 biologic-na?ve patients with moderate -to-severe CD treated at the Huai'an First People 's Hospital and The Second People 's Hospital of Huai'an between May 2023 and January 2025. All patients received standard induction therapy with UST，followed by maintenance therapy every 8weeks，with a total follow-up period of 52 weeks. The primary endpoint was clinical remission rate at week 44［defined as the ratio of Crohn's Disease Activity Index（CDAI）<150］. Secondary endpoints included endoscopic remission rate at week 52［defined as the ratio of Simplified Endoscopic Score for CD（SES -CD）≤2］，steroid -free clinical remission rate，changes in serum C-reactive protein（CRP）and faecal calprotectin（FC）levels，and adverse events. Results At baseline，the 65 patients had a CDAI of 283.0±46.0 and a SES -CD score of 10.1±3.0. By week 44 of treatment，the clinical remission rate reached 73.8%；at week 52，the endoscopic remission rate was 40.0%，and the steroid -free clinical remission rate was 63.1%. From pre-treatment to 52 weeks of treatment，serum CRP dropped from 27.3（21.5，31.2）mg/L to 4.7（4.1，8.6）mg/L（Z=6.901，P <0.01），and FC dropped from 740.0（650.0，930.0）μg/g to 120.0（97.5，205.0）μg/g（Z=7.009，P<0.01），with both differences being statistically significant. During the entire follow-up period，the overall adverse event rate was 30.8%，including 1 case of severe infection case（1.5%），and no tuberculosisor malignancy-related adverse events were observed. The treatment continuation rate was 93.8%. Conclusion UST can induce clinical remission and maintain long-term efficacy in biologic-naive patients with moderate-to-severe CD，demonstrating favorable safety and high treatment persistence.