Statistical Analysis
A chi-square test was used for comparing the categorical variables between case and comparison groups. The mean age was examined using the student t -test. Then, we calculated the IBD incidence rates (per 10 000 person years) among the 2 groups. Hazard ratios (HRs) were estimated using a Cox proportional hazards model and adjusted using the variables of age, sex, and comorbidities into the multivariable Cox proportional hazards model. Furthermore, we analyzed the association between the follow-up period and IBDs. The cumulative incidences of IBDs in the 2 groups were estimated using the Kaplan–Meier method. Furthermore, the log-rank test was used to evaluate the difference between the 2 curves. The statistical significance level was represented by a P value of <.05 for all tests.