OBJECTIVETo evaluate the effect and safety of low-dose aspirin for primary prevention of cardiovascular events.

METHODSWe searched for randomized controlled trials (RCT) in the following electronic databases: MEDLINE, EMbase, the Cochrane Library (Issue 3, 2008), CBM, CNKI. Quality assessment and data extraction were conducted by two reviewers independently. All data were analyzed using Review Manager 4.2.

RESULTSSix studies (TPT, HOT, PPP, WHS, POPADAD, J-PAD) involving a total of 72,466 participants met the inclusion criteria. Meta-analysis results showed that: (1) Compared with placebo, the incidences of total cardiovascular events (RR = 0.85, 95% CI: 0.80-0.92), stroke (RR = 0.87, 95% CI: 0.77-0.98), nonfatal stroke (RR = 0.81, 95% CI: 0.70-0.95) and transient ischemic attack (RR = 0.76, 95% CI: 0.64-0.90) were significantly lower in low-dose aspirin group than those in placebo control group (all P < 0.05). (2) Nonfatal myocardial infarction (RR = 0.89, 95% CI: 0.77-1.02), death from cardiovascular causes (RR = 0.98, 95% CI: 0.86-1.13) and death from any cause (RR = 0.95, 95% CI: 0.88-1.02) were similar between the 2 groups (all P > 0.05). (3) The risk of coronary heart disease was reduced in low-dose aspirin group in the elderly (RR = 0.81, 95% CI: 0.70-0.94, P < 0.05). (4) The risk of bleeding was higher in low aspirin group compared to placebo group (RR = 1.15, 95% CI: 1.12-1.18, P < 0.01).

CONCLUSIONSLow-dose aspirin use could reduce the incidences of total cardiovascular events, stroke, nonfatal stroke and transient ischemic attack but increase the risk of bleeding, the incidence of nonfatal myocardial infarction, death from cardiovascular causes and death from any cause was not affected by low-dose aspirin use. Low-dose aspirin use was also significantly reduced the risk of coronary heart disease in the elderly.