TABLE 6

Adjusted Association Between Antianaerobic Antibiotic Exposure and IBD Development According to IBD Type and Exposure Measurea

Exposure MeasureCrohn’s Disease (n = 449)bUlcerative Colitis (n = 272)
HR (95% CI)PHR (95% CI)P
Any exposurec1.71 (1.41–2.08)P < .0011.39 (1.08–1.79)P = .011
Per course1.06 (1.03–1.08)P < .0011.05 (1.01–1.09)P = .017
No. of coursesc
 0 1 (Reference)1 (Reference)
 1–2 1.61 (1.30–2.00)P < .0011.28 (0.97–1.70)P = .084
 >2 1.94 (1.49–2.52)P < .0011.65 (1.16–2.35)P = .005
Per week1.01 (0.99–1.02)P = .0721.01 (0.99–1.02)P = .37
No. of weeksc
 0 1 (Reference)1 (Reference)
 1–2 1.66 (1.33–2.06)P < .0011.28 (0.96–1.71)P = .091
 >2 1.80 (1.40–2.33)P < .0011.59 (1.14–2.22)P = .007
  • —, 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 Subjects with Crohn’s disease and ulcerative colitis do not total 748 because 27 subjects developed IBD with unclassified subtype.

  • c Hazard did not vary according to age.