Epidemiological Characteristics and Efficacy Evaluation of Difficult-To-Treat Crohn's Disease

Difficult to treat Crohn's disease (DTT-CD) was defined by the International Organization for the Study of Inflammatory Bowel Diseases (IOIBD) in 2023, which refers to CD patients with poor response to drug treatment and poor prognosis. Foreign epidemiological studies have shown that DTT-CD accounts for 24.8% of all CD patients, and most of them are patients with advanced treatment failure according to more than two different mechanisms. Our previous retrospective data suggested that compared with foreign DTT-CD patients, there was no significant difference in the proportion of patients with advanced treatment failure due to more than two different mechanisms, but the proportion of patients with recurrence after two intestinal resection and complex anal fistula was increased. Therefore, this project aims to determine the current prevalence and epidemiological status of DTT-CD in China; To clarify the difference in efficacy and prognosis between DTT-CD patients and non DTT-CD patients using advanced treatment (including biological agents and small molecule drugs); Objective to evaluate the incidence and risk factors of non DTT-CD patients progressing to DTT-CD within 1 year. To further verify whether the domestic DTT-CD population is significantly different from the foreign population, and provide theoretical support for the selection of subsequent treatment options.