Christopher M. Rembold, MD
What are the efficacy and safety of aspirin for primary prevention of vascular and nonvascular outcomes?
Included studies compared aspirin for primary prevention with placebo in ≥ 1000 participants without previous coronary heart disease (CHD) or stroke; had ≥ 1 year of follow-up; measured CHD or cardiovascular disease (CVD) outcomes (CHD, stroke, cerebrovascular disease, heart failure, or peripheral arterial disease [PAD]) as primary endpoints; and reported bleeding events. Exclusion criteria were mixed primary and secondary prevention and pilot studies. Primary outcomes were total CHD and cancer mortality. Secondary outcomes were nonfatal myocardial infarction (MI), fatal MI, stroke, total CVD events, CVD mortality, and all-cause mortality. Composite safety outcome was nontrivial bleeding (fatal bleeding from any site, cerebrovascular or retinal bleeding, bleeding from hollow viscus, bleeding requiring hospitalization or transfusion, or study-defined major bleeding).
PubMed and Cochrane Library (both to Jun 2011) and reference lists were searched for randomized controlled trials (RCTs). Additional data on cancer and nonvascular outcomes were obtained from subsequent trial reports, a recent meta-analysis, and study authors. 9 RCTs (n = 102 621, weighted mean age 57 y, 54% women) met inclusion criteria. 5 RCTs met all 9 quality criteria, 2 did not include intention-to-treat analysis, and 2 did not blind care providers or patients.
The main results of the meta-analyses are in the Table.
Aspirin for primary prevention reduces nonfatal myocardial infarction but not total coronary heart disease or cancer mortality; risk for bleeding is increased.
Aspirin vs placebo for primary prevention*
*CHD = coronary heart disease; CVD = cardiovascular disease; MI = myocardial infarction; NS = not significant; other abbreviations defined in Glossary. RRR, RRI, NNT, NNH, and CI calculated from control event rates and odds ratios in article using a random-effects model.
†Calculated NNTs and NNHs differ quantitatively, but not in direction, from those reported in the article.
Rembold CM. Review: Aspirin does not reduce CHD or cancer mortality but increases bleeding. Ann Intern Med. ;156:JC6–3. doi: 10.7326/0003-4819-156-12-201206190-02003
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Published: Ann Intern Med. 2012;156(12):JC6-3.
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