For qualitative variables, percentages will be calculated (with their 95% confidence intervals) and for quantitative variables, the arithmetic mean and standard deviation will be determined. In the univariate analysis, categorical variables will be compared using a Chi-squared (X2) test and quantitative variables will be compared using the appropriate test (Student's t-test, Wilcoxon, etc. depending on whether their values follow a normal distribution or not). To examine in detail the time course of the use of treatments, hospital admissions, surgery or occurrence of complications, the Kaplan-Meier method will be used, and the differences between the curves will be compared with the log-rank test. A Cox regression model will be used to study which variables are associated with the probability of occurrence of complications, progression to more severe phenotypes, use of immunosuppressive or biologic drugs, hospital admission, and performance of surgery.