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
10Â 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.