Multivariable Cox proportional hazards analysis of risk factors for UST failure in patients with UC. Hazard ratios of various covariates influencing the risk of UST failure in patients with UC undergoing UST treatment. Concomitant use of IMs is identified as a significant risk factor, while the use of 5-ASA appears to be a protective factor against UST failure. Abbreviation: 5-ASA, 5-aminosalicylic acid; IMs, immunomodulators; UC, ulcerative colitis; UST, ustekinumab.