Table 3

Incidence rate ratio by timing of antibiotic course

Age groupMost recent antibiotic useIRR*, IBDIRR lower bound, IBDIRR upper bound, IBDIRR*, CDIRR lower bound, CDIRR upper bound, CDIRR*, UCIRR lower bound, UCIRR upper bound, UC
10–40 yearsNo use in the last 5 years1.
10–40 years4 to 5 years1.
10–40 years3 to 4 years1.
10–40 years2 to 3 years1.
10–40 years1 to 2 years1.401.351.441.591.511.681.281.231.34
40–60 yearsNo use in the last 5 years1.
40–60 years4 to 5 years1.
40–60 years3 to 4 years1.361.291.441.361.221.521.371.281.46
40–60 years2 to 3 years1.411.341.481.531.391.681.371.291.45
40–60 years1 to 2 years1.661.591.731.891.752.041.581.511.66
60+yearsNo use in the last 5 years1.
60+years4 to 5 years1.221.141.311.231.061.411.221.121.33
60+years3 to 4 years1.261.181.331.291.151.461.251.161.34
60+years2 to 3 years1.391.321.461.371.241.521.411.321.49
60+years1 to 2 years1.631.571.701.721.581.861.621.541.70
  • *Adjusted for sex, calendar time, antiviral and antifungal exposure, proton pump inhibitor exposure, socioeconomic index and population density.

  • CD, Crohn's disease; IBD, inflammatory bowel disease; IRR, incidence rate ratio; UC, ulcerative colitis.