P2Y12 inhibitor versus aspirin monotherapy for secondary prevention of cardiovascular events: meta-analysis of randomized trials

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  Figure 1. Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) flow chart for the study. Search of Medline, EMBASE, and Cochrane Central databases revealed 6058 citations. Of these, 9 studies met the inclusion criteria and were included in the analyses.

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  Figure 2. Major adverse cardiovascular events (MACE) in P2Y12 inhibitor monotherapy versus aspirin monotherapy. The primary efficacy outcome of interest was MACE, which was defined as a composite of stroke, myocardial infarction (MI), or death in the majority of studies. The DerSimonian and Laird random-effects model was used to examine the risk ratios (RR). All 9 trials were included for this analysis. P2Y12 inhibitor monotherapy reduced the risk of MACE by 11% as compared with aspirin monotherapy (RR 0.89 [95% CI 0.84-0.95], I2 = 0%). This result was consistent irrespective of the P2Y12 inhibitor used (p-interaction = 0.83). CI = confidence interval, MACE = major adverse cardiovascular events, P2Y12i = P2Y12 inhibitor, RR = risk ratio.

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  Figure 3. Major bleeding in P2Y12 inhibitor monotherapy versus aspirin monotherapy. The primary safety outcome of interest was major bleeding was evaluated using the DerSimonian and Laird random-effects model. There was no significant difference in the risk of major bleeding between P2Y12 inhibitor and aspirin monotherapy (RR 0.94 [95% CI 0.72–1.22], I2 = 42.6%). CI = confidence interval, MB = major bleeding, P2Y12i = P2Y12 inhibitor, RR = risk ratio.

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  Figure 4. Myocardial infarction (MI) in P2Y12 inhibitor monotherapy versus aspirin monotherapy. Pooled risk ratio (RR) of MI was calculated from 8 of the 9 included trials. The use of P2Y12 inhibitors was associated with a 19% risk reduction of MI as compared with aspirin (RR 0.81 [95% CI 0.71–0.92], I2 = 0%). CI = confidence interval, MI = myocardial infarction, P2Y12i = P2Y12 inhibitor, RR = risk ratio.

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  Figure 5. Stroke in P2Y12 inhibitor monotherapy versus aspirin monotherapy. The occurrence of stroke (ischemic/hemorrhagic) was reported in 7 trials. No significant difference was observed in the risk of stroke (RR 0.85 [95% CI 0.73–1.01], I2 = 43.3%). CI = confidence interval, P2Y12i = P2Y12 inhibitor, RR = risk ratio.

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  Figure 6. All-cause mortality in P2Y12 inhibitor monotherapy versus aspirin monotherapy. All-cause death was analyzed as a secondary outcome from the pooled analysis of 8 studies. Monotherapy with a P2Y12 inhibitor or aspirin had similar risks of all-cause death (RR 1.01 [95% CI 0.92–1.11], I2 = 0%). CI = confidence interval, P2Y12i = P2Y12 inhibitor, RR = risk ratio.

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