Table 4:

Overall antibiotic use and inflammatory bowel disease comparing cases and their unaffected siblings, 2007–2016

	Cumulative antibiotic use
	No prior use	1 prior dispensation	2 prior dispensations	≥3 prior dispensations	P-trend
Inflammatory bowel disease (IBD)#
Cases, n (%)	6,502 (40)	3,407 (21)	2,170 (13)	4,274 (26)
Siblings, n (%)	12,688 (44)	6,278 (22)	3,341 (12)	6,425 (22)
Multivariable OR (95% CI)‡	1·0 (ref)	1·06 (1·01, 1·12)	1·32 (1·24, 1·41)	1·35 (1·28, 1·43)	<0·0001
Ulcerative colitis (UC)
Cases, n (%)	4,428 (41)	2,279 (21)	1,392 (13)	2,739 (25)
Siblings, n (%)	8,459 (45)	4,209 (22)	2,204 (11)	4,160 (22)
Multivariable OR (95% CI)	1·0 (ref)	1·06 (0·99, 1·14)	1·23 (1·13, 1·34)	1·29 (1·20, 1·39)	<0·0001
Crohn’s disease (CD)
Cases, n (%)	2,036 (38)	1,117 (20)	762 (14)	1,514 (28)
Siblings, n (%)	4,073 (43)	2,030 (21)	1,111 (12)	2,221 (24)
Multivariable OR (95% CI)	1·0 (ref)	1·13 (1·02, 1·25)	1·41 (1·26, 1·58)	1·46 (1·23, 1·62)	<0·0001

Cumulative dispensations accrued from study baseline up until one year prior to case diagnosis.

Abbreviations: OR - odds ratio, CI - confidence interval

^#Includes ulcerative colitis, Crohn’s disease, and IBD-unclassified

^‡Further adjusted for age, sex, county, number of inpatient and outpatient encounters, and education level