Data collection

The electronic case report forms of CHASE-IBD were designed to ensure standardization and consistency of data collection. The CHASE-IBD system is maintained by specific personnel, including data processing engineers, doctors, and nurses. Before each hospital integrated the use of the database into their operations, the doctors and nurses of the IBD-specific clinics were trained in the collection and entry of clinical data by the professional staff of CHASE-IBD. Upon approval by the IBD Group, Chinese Society of Gastroenterology, Chinese Medical Association, exclusive accounts granting access to the database are provided to participating hospitals for patient data collection, limited to the clinical data of patients in each hospital. Patients with IBD ages ⩾18 years were prospectively enrolled in the CHASE-IBD cohort when they visited the IBD-specific clinics at each hospital. Patients aged <18 years old were enrolled into a pediatric database. The clinical data of patients with IBD who were diagnosed before the clinic participated in the database were collected retrospectively from electronic medical records. A dedicated data collector performed data collection at the time of enrollment and all subsequent clinic visits or hospitalizations and then recorded the data on a dedicated website using the standardized electronic case report forms.

Data captured into the database included demographic data, IBD diagnosis, time of diagnosis, extra-intestinal manifestations (EIMs), Montreal classification phenotype, disease activity scores, medication history, surgical records, and related laboratory, radiographic, and endoscopic findings. The diagnosis and treatment of IBD were based on the Chinese consensus on the diagnosis and treatment of IBD, which was similar to the European Crohn’s and Colitis Organization (ECCO) consensus.^16,17