Table 3.

Remote period duration of aspirin use,^a recent period duration of aspirin use,^b and CRC risk in the pooled NHS and HPFS

Pooled NHS and HPFS	Regular aspirin use, y				P trend c	Per 5-year increment HR (95% CI)	P trend d
	0	1-5	6-10	>10
Remote period duration of aspirin usea
Median values	0	2	8	14	—	—	—
No. of CRC cases (2147 in total)	1050	612	353	132	—	—	—
Age-adjusted model, HR (95% CI)e	1 (Reference)	0.79 (0.71 to 0.87)	0.67 (0.59 to 0.75)	0.70 (0.58 to 0.86)	<.001	0.83 (0.79 to 0.88)	<.001
MV-adjusted model, HR (95% CI)f	1 (Reference)	0.79 (0.72 to 0.88)	0.68 (0.60 to 0.77)	0.72 (0.60 to 0.88)	<.001	0.84 (0.79 to 0.90)	<.001
MVf + recent period duration of aspirin useb adjusted model, HR (95% CI)	1 (Reference)	0.83 (0.75 to 0.92)	0.73 (0.63 to 0.83)	0.79 (0.65 to 0.97)	<.001	0.88 (0.83 to 0.94)	<.001
Recent period duration of aspirin useb
Median values	0	2	8	—	—	—	—
No. of CRC cases (2147 in total)	855	571	721	—	—	—	—
Age-adjusted model, HR (95% CI)e	1 (Reference)	0.88 (0.79 to 0.97)	0.72 (0.65 to 0.80)	—	<.001	0.83 (0.78 to 0.88)	<.001
MV-adjusted morel, HR (95% CI)f	1 (Reference)	0.88 (0.79 to 0.99)	0.75 (0.67 to 0.83)	—	<.001	0.84 (0.79 to 0.90)	<.001
MVf + remote period duration of aspirin usea adjusted model, HR (95% CI)	1 (Reference)	0.94 (0.84 to 1.05)	0.84 (0.74 to 0.94)	—	.002	0.90 (0.84 to 0.96)	.002

^aRemote period duration of aspirin use: duration of regular aspirin use during every specific remote period (>10 years before every follow-up period, ie, began from 1980 [NHS] and 1986 [HPFS] and then was extended by every 2-year subsequent interval at a time until 2002). AHEI = Alternate Healthy Eating Index score; BMI = body mass index; CI = confidence interval; CRC = colorectal cancer; HPFS = Health Professionals Follow-up Study; HR = hazard ratio; MV = multivariable; NHS = Nurses’ Health Study; NSAIDs = nonsteroidal antiinflammatory drugs.

^bRecent period duration of aspirin use: duration of regular aspirin use during every specific subsequent 10-year period after the remote periods.

^cAdjusted for age and follow-up cycle in the follow-up period.

^dAdjusted for age, follow-up cycle, sex, race, pack-years of smoking, physical activity, BMI, alcohol consumption, AHEI, regular use of nonaspirin NSAIDs, family history of CRC, history of diabetes mellitus, screening colonoscopy or sigmoidoscopy in the past 2 years, multivitamin use, total calorie intake, red or processed meat intake, fiber intake, folate intake, calcium intake, and vitamin D intake in the follow-up period.

^e P _trend was calculated using the mid-point of each category of aspirin use in years.

^f P _trend was the P value for variables modeled as continuous.