TABLE 1

Baseline Cohort Demographic Characteristics According to Antianaerobic Antibiotic Exposure Status

Overall Cohort (N = 1 072 426)Unexposed (N = 453 763)Exposed (N = 618 663)
Total person time, y3 776 9422 859 887
Male gender, n (%)243 726 (53.7%)311 796 (50.4)
Years in cohort, median (IQR)4.6 (2.9–7.3)6.5 (4.2–9.1)
Years of age at entry, median (IQR)7.3 (2.2–12.1)4.2 (0.2–9.8)
Country of residence, n (%)
 England379 971 (83.7)504 069 (81.5)
 North Ireland12 157 (2.7)30 539 (4.9)
 Scotland40 370 (8.9)46 996 (7.6)
 Wales21 265 (4.7)37 059 (6.0)
Developed IBD, n (%)312 (0.07)436 (0.07)
Subjects with predisposition to IBD, n (%)
 Chronic osteomyelitis16 (<0.01)60 (0.01)
 Behçet’s syndrome1 (<0.01)19 (<0.01)
 Chronic granulomatous disease7 (<0.01)12 (<0.01)
 Primary sclerosing cholangitis7 (<0.01)10 (<0.01)
 Common variable immunodeficiency1 (<0.01)16 (<0.01)
 Hyperimmunoglobulin E syndrome1 (<0.01)1 (<0.01)
Family history of IBD, n (%)121 (0.03)235 (0.04)
Townsend quintile, n (%)
 1–4 (less deprivation)363 747 (80.2)503 162 (81.3)
 5 (most deprivation)59 604 (13.1)81 165 (13.1)
 Missing30 412 (6.7)34 336 (5.6)