Table 4.

Association between use of oral antibiotics and risk of early-onset colorectal cancer (age < 50 years) by anatomic location

	Nonusers		Users		OR (95% CI)
	Cases (n)	Controls (n)	Cases (n)	Controls (n)	Model 1a	Model 2b
Proximal colon
All antibiotics	92	481	126	587	1.14 (0.83, 1.57)	0.99 (0.71, 1.39)
Spectrum of coverage
Broad spectrum	152	778	66	290	1.18 (0.84, 1.64)	0.94 (0.65, 1.35)
Narrow spectrum	113	578	105	490	1.11 (0.82, 1.52)	1.04 (0.75, 1.45)
Bacterial target
Antiaerobic	94	496	124	572	1.17 (0.85, 1.61)	1.01 (0.72, 1.42)
Antianaerobic	194	968	24	100	1.21 (0.74, 1.96)	0.79 (0.45, 1.41)
Distal colon
All antibiotics	131	685	178	852	1.11 (0.85, 1.45)	1.05 (0.79, 1.39)
Spectrum of coverage
Broad spectrum	210	1,088	99	449	1.15 (0.88, 1.53)	1.12 (0.84, 1.50)
Narrow spectrum	157	831	152	706	1.15 (0.88, 1.50)	1.08 (0.81, 1.43)
Bacterial target
Antiaerobic	134	698	175	839	1.11 (0.85, 1.44)	1.04 (0.79, 1.38)
Antianaerobic	264	1,353	45	184	1.26 (0.87, 1.80)	1.13 (0.77, 1.66)
Rectal
All antibiotics	424	2,198	506	2,380	1.12 (0.96, 1.31)	1.04 (0.88, 1.22)
Spectrum of coverage
Broad spectrum	659	3,386	271	1,192	1.18 (1.00, 1.38)	1.06 (0.90, 1.26)
Narrow spectrum	524	2,589	406	1989	1.01 (0.87, 1.18)	0.93 (0.79, 1.09)
Bacterial target
Antiaerobic	437	2,247	493	2,331	1.10 (0.94, 1.28)	1.01 (0.86, 1.19)
Antianaerobic	824	4,133	106	445	1.20 (0.95, 1.50)	0.98 (0.77, 1.26)

CI, confidence interval.

^aConditional logistic regression was used with matching for age (continuous), sex (binary), calendar year at the time of match, and county of residence.

^bMultivariable conditional logistic regression models were further adjusted for education (9 years or less, 10–12 years, ≥13 years, and missing), number of clinic visits (continuous), number of hospitalizations (continuous), Charlson Comorbidity Score (continuous), and number of previous lower endoscopies (continuous).