Table 3.

Risk of advanced adenomas with randomized aspirin treatment and subsequent NSAID use^*

Study phase		No. of subjects with adenoma/ Total no. of subjects (%)	Adjusted RR (95% CI)
Randomized trial†
Placebo		38/285 (13.3)	1.00 (reference)
Aspirin		56/565 (9.9)	0.73 (0.50 to 1.09)
Low-dose aspirin		26/284 (9.2)	0.66 (0.41 to 1.07)
High-dose aspirin		30/281 (10.7)	0.81 (0.51 to 1.29)
Posttreatment observational follow-up‡
Aspirin treatment group	Posttreatment NSAID Use§
Placebo	<2 days per week	25/203 (12.3)	1.00 (reference)
Placebo	≥2 days per week	4/75 (5.3)	0.44 (0.15 to 1.27)
Aspirin	<2 days per week	28/386 (7.3)	0.61 (0.35 to 1.04)
Aspirin	≥2 days per week	14/169 (8.3)	0.68 (0.35 to 1.32)
Low-dose aspirin	<2 days per week	12/194 (6.2)	0.54 (0.27 to 1.08)
Low-dose aspirin	≥2 days per week	3/84 (3.6)	0.31 (0.09 to 1.04)
High-dose aspirin	<2 days per week	16/192 (8.3)	0.67 (0.36 to 1.25)
High-dose aspirin	≥2 days per week	11/85 (12.9)	0.99 (0.48 to 2.05)

^*Included 833 participants who completed study questionnaires and had at least one colonoscopy during the posttreatment follow-up period. “Aspirin” refers to both doses combined. RR = relative risk; CI = confidence interval; low-dose aspirin = 81 mg; high-dose aspirin = 325 mg; NSAIDs = nonsteroidal anti-inflammatory drug.

^†Relative risks adjusted for age, sex, clinical center, number of lifetime adenomas before randomization, and duration of follow-up until the end of randomized treatment.

^‡Relative risks adjusted for aspirin dose, age, sex, center, body mass index, time to year 3 study colonoscopy (overall aspirin treatment effects) or time to first colonoscopy after the end of randomized treatment (posttreatment NSAID effects), number of lifetime adenomas before randomization, and presence of adenomas during the randomized period.

^§NSAID use defined as the average number of days per week subjects took NSAIDs between the end of randomized aspirin treatment and the subsequent posttreatment colonoscopy.