Random-effects risk ratio forest
plot comparing any aspirin vs placebo.
Trial-specifi c risk ratios are shown as
black squares , with the size of the square
being inversely proportional to the trialspecifi
c risk ratio variance. Horizontal
lines represent 95% confi dence intervals
for the trial-specifi c risk ratios. Pooled risk
ratios are shown as diamonds . The middle
of each diamond corresponds to the
risk ratio, and the width of each diamond
represents the 95% confi dence interval.
The vertical dashed lines provide a visual
comparison of the pooled risk ratio with
the corresponding trial-specifi c risk ratios.
Tests for heterogeneity are as follows. For
any adenoma, Q = 5.13 ( P = 0.16) and I 2 =
41.5. For advanced lesion, Q = 1.27 ( P =
.74) and I 2 = 0.0. AFPPS = Aspirin/Folate
Polyp Prevention Study; APACC =
Association pour la Prevention par
l’Aspirine du Cancer Colorectal; CALGB =
Cancer and Leukemia Group B; CI = confi -
dence interval; ukCAP = United Kingdom
Colorectal Adenoma Prevention.