Table 2.

Odds ratios for the association between aspirin use and occurrence of colorectal adenoma.

Aspirin use	Adenoma cases	Lower Endoscopiesa	Age-adjusted OR (95% CI)	MV-adjusted OR (95% CI)b
Non-usec	1,038	44,026	1.00 (ref)	1.00 (ref)
Ever	826	40,622	0.85 (0.77–0.93)	0.86 (0.78–0.95)
Past	369	19,025	0.81 (0.72–0.92)	0.83 (0.73–0.94)
Current	457	21,597	0.88 (0.78–0.99)	0.89 (0.79–1.01)
Duration of use
<5 years	455	21,003	0.91 (0.81–1.01)	0.91 (0.81–1.02)
5–9 years	205	9,902	0.86 (0.73–1.00)	0.87 (0.74–1.01)
≥10 years	144	7,455	0.79 (0.66–0.95)	0.80 (0.66–0.96)
Per 5-year increase in duration			0.91 (0.86–0.98)	0.92 (0.86–0.98)
Age at aspirin initiation
<40 years	87	5,407	0.68 (0.55–0.85)	0.69 (0.55–0.86)
40–59 years	580	27,678	0.88 (0.79–0.98)	0.90 (0.80–1.00)
60–64 years	90	3,968	0.95 (0.75–1.20)	0.98 (0.77–1.24)
≥65 years	63	3,061	0.85 (0.64–1.13)	0.89 (0.67–1.19)

OR, Odds ratio; CI, Confidence interval; MV, Multivariable.

^aTotal number of lower endoscopies among the 34,397 participants with at least one lower endoscopy reported. Some participants reported more than one lower endoscopy over the study period.

^bOdds ratios adjusted for age (continuous), family history of colorectal cancer (yes, no), smoking status (never, past, current), alcohol consumption (non-current, current 1–6, current ≥7 drinks/week), vigorous exercise (none, <5, ≥5 hours/week), red meat consumption (quartiles), type 2 diabetes (yes, no), and postmenopausal hormone use (yes, no).

^cNon-users are defined as participants who did not report regular aspirin use during the study period.