COHORT A characteristics comparing non-IBD controls with IBD cases (≥15 years).

1Estimated using IBD-drug use and surgical interventions during follow-up as proxies (see text for further detail)2 43% of patients had missing data3 17.4% of patients had missing data4Index of Multiple Deprivation (IMD) based on practice post-code. Quintile 0 is the least deprived, quintile 4 is the most deprived. 67.5% of patients had missing data.5Ever in patient record6 Non-IBD compared to IBD, comparison of binary variables by adjusted χ2 test; continuous variables by Student’s t-test; multiple category variables by χ2 test adjusted for trend.COHORT A characteristics comparing non-IBD controls with IBD cases (≥15 years).