TABLE 4

Summary of Adjusted Multivariate Associations Between Antibiotic Exposure and IBD Development According to Antibiotic Class and Exposure Measurea

Exposure MeasureAny AntibioticAntianaerobic AntibioticsPenicillins
HR (95% CI)PHR (95% CI)PHR (95% CI)P
Any exposureb5.00 (1.47–17.03)P = .015.51 (1.66–18.28)P = .0055.26 (1.60–17.25)P = .006
Per course1.04 (1.03–1.05)P < .0011.06 (1.04–1.08)P < .0011.06 (1.03–1.08)P < .001
No. of coursesb
 0 1 (Reference)1 (Reference)1 (Reference)
 1–23.13 (1.54-6.36)P = .0023.33 (1.69–6.58)P = .0012.83 (1.44–5.56)P = .003
 >2 5.15 (2.36–11.25)P < .0014.77 (2.13–10.68)P < .0015.83 (2.59–13.14)P < .001
Per week1.01 (1.00–1.02)P = .0011.01 (1.00–1.02)P = .0181.01 (1.00–1.02)P = .017
No. of weeksb
 0 1 [Reference]1 (Reference)1 (Reference)
 1–2 3.10 (1.50–6.41)P = .0023.04 (1.51–6.11)P = .0022.57 (1.28–5.16)P = .008
 >2 4.87 (2.30–10.34)P < .0015.23 (2.43–11.29)P < .0016.19 (2.84–13.49)P < .001
Exposure MeasureMacrolidesSulfonamidesCephalosporins
HR (95% CI)P HR (95% CI)P HR (95% CI)P
Any exposurec1.21 (0.96–1.51)P = .101.31 (0.98–1.74)P = .0681.58 (1.21–2.05)P = .001
Per course1.03 (0.95–1.11)P = .521.03 (0.99–1.08)P = .1631.04 (1.00–1.07)P = .026
No. of coursesc
 0 1 (Reference)1 (Reference)1 (Reference)
 1–21.22 (0.96–1.55)P = .111.29 (0.95–1.74)P = .101.56 (1.18–2.06)P = .002
 >2 1.16 (0.69–1.94)P = .591.45 (0.67–3.14)P = .341.71 (0.88–3.34)P = .12
Per week1.01 (0.99–1.03)P = .421.01 (1.00–1.03)P = .0431.01 (0.99–1.03)P = .17
No. of weeksc
 0 1 (Reference)1 (Reference)1 (Reference)
 1–2 1.27 (0.98–1.63)P = .061.31 (0.96–1.80)P = .0921.59 (1.20–2.12)P = .001
 >2 1.04 (0.68–1.60)P = .861.28 (0.69–2.38)P = .441.49 (0.81–2.74)P = .20
  • —, not applicable.

  • a Excludes exposures during the median latency period (3.9 months) before cohort censorship for all subjects. The model included family history of IBD, gender, chronic granulomatous disease, primary sclerosing cholangitis, and socioeconomic deprivation for all listed associations.

  • b Represents the increased hazard of developing IBD with exposure before 1 year of age; hazard decreased with increasing age.

  • c Hazard did not vary according to age.