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Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews.

Effect of smoking on comparative efficacy of antiplatelet agents: systematic review, meta-analysis, and indirect comparison

Review published: 2013.

Bibliographic details: Gagne JJ, Bykov K, Choudhry NK, Toomey TJ, Connolly JG, Avorn J.  Effect of smoking on comparative efficacy of antiplatelet agents: systematic review, meta-analysis, and indirect comparison. BMJ 2013; 347: f5307. [PMC free article: PMC3775704] [PubMed: 24046285]

Quality assessment

This review concluded that the efficacy of antiplatelets differed for smokers and nonsmokers, with the benefit occurring mostly for smokers and less so for nonsmokers. The review did not evaluate adverse events, so the risk-benefit profiles of the drugs are unknown, and the usefulness of the results for informing clinical practice is limited. Full critical summary

Abstract

OBJECTIVE: To evaluate whether smoking status is associated with the efficacy of antiplatelet treatment in the prevention of cardiovascular events.

DESIGN: Systematic review, meta-analysis, and indirect comparisons.

DATA SOURCES: Medline (1966 to present) and Embase (1974 to present), with supplementary searches in databases of abstracts from major cardiology conferences, the Cumulative Index to Nursing and Allied Health (CINAHL) and the CAB Abstracts databases, and Google Scholar.

STUDY SELECTION: Randomized trials of clopidogrel, prasugrel, or ticagrelor that examined clinical outcomes among subgroups of smokers and nonsmokers.

DATA EXTRACTION: Two authors independently extracted all data, including information on the patient populations included in the trials, treatment types and doses, definitions of clinical outcomes and duration of follow-up, definitions of smoking subgroups and number of patients in each group, and effect estimates and 95% confidence intervals for each smoking status subgroup.

RESULTS: Of nine eligible randomized trials, one investigated clopidogrel compared with aspirin, four investigated clopidogrel plus aspirin compared with aspirin alone, and one investigated double dose compared with standard dose clopidogrel; these trials include 74,489 patients, of whom 21,717 (29%) were smokers. Among smokers, patients randomized to clopidogrel experienced a 25% reduction in the primary composite clinical outcome of cardiovascular death, myocardial infarction, and stroke compared with patients in the control groups (relative risk 0.75, 95% confidence interval 0.67 to 0.83). In nonsmokers, however, clopidogrel produced just an 8% reduction in the composite outcome (0.92, 0.87 to 0.98). Two studies investigated prasugrel plus aspirin compared with clopidogrel plus aspirin, and one study investigated ticagrelor plus aspirin compared with clopidogrel plus aspirin. In smokers, the relative risk was 0.71 (0.61 to 0.82) for prasugrel compared with clopidogrel and 0.83 (0.68 to 1.00) for ticagrelor compared with clopidogrel. Corresponding relative risks were 0.92 (0.83 to 1.01) and 0.89 (0.79 to 1.00) among nonsmokers.

CONCLUSIONS: In randomized clinical trials of antiplatelet drugs, the reported clinical benefit of clopidogrel in reducing cardiovascular death, myocardial infarction, and stroke was seen primarily in smokers, with little benefit in nonsmokers.

CRD has determined that this article meets the DARE scientific quality criteria for a systematic review.

Copyright © 2014 University of York.

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