Table 2.

Patient characteristics and effect of aspirin on the reduction of colorectal adenoma risk (Baron et al, 2003; Benamouzig et al, 2003; Cole et al, 2009; Logan et al, 2008; Sandler et al, 2003).

	APACC	AFPPS	CALGB	ukCAP
Design	Randomized controlled trial Aspirin (160 or 300 mg/day) or placebo Follow-up: 4 years	Randomized controlled trial Aspirin (81 or 325 mg/day) or placebo Follow-up: 3 years	Randomized controlled trial Aspirin (325 mg/day) or placebo Median follow-up: 12.8 months	Randomized trial Aspirin (300 mg/day) or folate supplement (0.5 mg/day) Follow-up: 3 years
Patients (n)	272	1,121	635	945
Adenoma inclusion criteria	Recent history of colorectal adenomas	Recent history of colorectal adenomas	Previous history of CRCs	Recent history of colorectal adenomas
Family history of adenomas (%)	34.6	30.4	Not reported	14.1
Risk ratio (95% CI) for any adenoma*	0.95 (0.75–1.21)	0.88 (0.77–1.02)	0.61 (0.44–0.86)	0.79 (0.63–0.99)
Risk ratio (95% CI) for advanced adenoma*	0.91 (0.51–1.60)	0.74 (0.52–1.06)	0.77 (0.29–2.05)	0.63 (0.43–0.91)

^*Versus placebo or folate (based on colonoscopic follow-up). AFPPS, Aspirin/Folate Polyp Prevention Study; APACC, Association pour la Préventionparl’Aspirine du Cancer Colorectal; CALGB, Colorectal Adenoma prevention study originated in the cooperative trials group cancer and Leukemia Group B; ukCAP, United Kingdom Colorectal Adenoma Prevention; CRC, colorectal cancer; CI, confidence interval.