Table 2

Associations between ulcerative colitis and Crohn's disease, and each infection outcome.

Number of patientsPatient years at-riskEvents (%)Event rate
(per 100-person years)
Hazard ratio (95% CI)
UnadjustedAdjusted*
A. Associations between ulcerative colitis and each infection outcome
Any common infection
 Controls45 440133 70317 403 (38%)13.0 (12.8, 13.2)1.00 (ref)1.00 (ref)
 Ulcerative colitis11 36031 0765111 (45%)16.4 (16.0, 16.9)1.25 (1.21 to 1.29)*1.12 (1.07 to 1.18)*
Gastrointestinal infection
 Controls45 440134 6151365 (3%)1.0 (0.9, 1.1)1.00 (ref)1.00 (ref)
 Ulcerative colitis11 36031 410510 (4%)1.6 (1.5, 1.8)1.61 (1.45 to 1.78)*1.46 (1.26 to 1.69)*
Viral infection
 Controls45 440136 2908510 (19%)6.2 (6.1, 6.4)1.00 (ref)1.00 (ref)
 Ulcerative colitis11 36031 9942544 (22%)8.0 (7.6, 8.3)1.27 (1.21 to 1.33)*1.13 (1.05 to 1.20)*
B. Associations between Crohn’s disease and each infection outcome
Any common infection
 Controls29 87688 75311 227 (38%)12.7 (12.4, 12.9)1.00 (ref)1.00 (ref)
 Crohn’s disease746919 8923470 (46%)17.4 (16.9, 18.0)1.36 (1.31 to 1.41)*1.20 (1.14 to 1.26)*
Gastrointestinal infection
 Controls29 87689 303841 (3%)0.9 (0.8, 1.0)1.00 (ref)1.00 (ref)
 Crohn’s disease746920 170395 (5%)2.0 (1.8, 2.2)2.09 (1.86 to 2.36)*1.83 (1.56 to 2.15)*
Viral infection
 Controls29 87690 5595917 (20%)6.5 (6.4, 6.7)1.00 (ref)1.00 (ref)
 Crohn’s disease746920 5311797 (24%)8.8 (8.4, 9.2)1.33 (1.26 to 1.40)*1.15 (1.07 to 1.23)*
  • *p<0.001.

  • *Models adjusted for age, sex, IMD quintile, white ethnicity, BMI category, smoking status, alcohol category, hypertension, hyperlipidaemia, type 2 diabetes, peripheral arterial disease, atrial fibrillation, angina, myocardial infarction, stroke, heart failure, chronic kidney disease stage 3–5, chronic obstructive pulmonary disorder, chronic liver disease, malignancy, dementia, rheumatoid arthritis, fracture history, depression and concomitant medication use (from rectal 5-ASA, rectal glucocorticoids, oral 5-ASA, oral glucocorticoids, immunotherapies and biologic therapies).

  • ASA, aminosalicylic acid; BMI, body mass index; IMD, index of multiple deprivation.