Comparative effectiveness of clopidogrel in medically managed patients with unstable angina and non-ST-segment
Matthew D Solomon1, Alan S Go2, David Shilane3
1Division of Research, Kaiser Permanente Northern California, Oakland, California; Stanford University School of Medicine, Stanford, California.
Insights
Clopidogrel use in medically managed unstable angina (UA) or non-ST-segment elevation myocardial infarction (NSTEMI) patients reduced mortality and death or MI composite risk. The benefit was most pronounced in NSTEMI patients.
Area of Science:
- Cardiology
- Pharmacology
- Clinical Medicine
Background:
- Clinical trials show clopidogrel efficacy in reducing cardiovascular events for UA/NSTEMI patients.
- Real-world effectiveness of clopidogrel in medically managed UA/NSTEMI patients remains less certain.
- This study evaluates clopidogrel's impact in a large, community-based cohort.
Purpose of the Study:
- To assess clopidogrel effectiveness in real-world, medically managed patients with unstable angina (UA) or non-ST-segment elevation myocardial infarction (NSTEMI).
- To determine the association between clopidogrel use and adverse cardiovascular outcomes in this population.
Main Methods:
- Retrospective cohort study of Kaiser Permanente Northern California members (2003-2008).
- Included patients presenting with UA or NSTEMI, managed medically without revascularization.
- Propensity-matched multivariable Cox analyses used to assess outcomes over 2-year follow-up.
Main Results:
- 16,365 patients identified; 36% received clopidogrel.
- In propensity-matched cohort (8,562 patients), clopidogrel users showed lower all-cause mortality (8.3% vs. 13.0%) and death/MI composite (13.5% vs. 17.4%).
- Significant benefit for death/MI composite observed in NSTEMI patients (HR: 0.67) but not UA patients (HR: 1.25).
Conclusions:
- Clopidogrel use is associated with reduced risk of death and MI in medically managed UA/NSTEMI patients.
- The protective effect of clopidogrel is particularly significant for patients presenting with NSTEMI.
- Findings support clopidogrel's role in real-world management of selected UA/NSTEMI patients.
Objectives:
This study sought to examine the effectiveness of clopidogrel in real-world, medically managed patients with unstable angina (UA) or non-ST-segment elevation myocardial infarction (NSTEMI).
Background:
Although clinical trials have demonstrated the efficacy of clopidogrel to reduce cardiovascular (CV) morbidity and mortality in medically managed patients with UA or NSTEMI, the effectiveness of clopidogrel in actual clinical practice is less certain.
Methods:
A retrospective cohort study was conducted of Kaiser Permanente Northern California members without known coronary artery disease or prior clopidogrel use who presented with UA or NSTEMI between 2003 and 2008 and were medically managed (i.e., no percutaneous coronary intervention or coronary artery bypass grafting during the index hospitalization or within 7 days post-discharge). Over 2 years of follow-up, we measured the association between clopidogrel use and all-cause mortality, hospital stay for MI, and a composite endpoint of death or MI using propensity-matched multivariable Cox analyses.
Results:
We identified 16,365 patients with incident UA (35%) or NSTEMI (65%); 36% of these patients were prescribed clopidogrel within 7 days of discharge. In 8,562 propensity score-matched patients, clopidogrel users had lower rates of all-cause mortality (8.3% vs. 13.0%; p < 0.01; adjusted hazard ratio [HR]: 0.63; 95% confidence interval [CI]: 0.54 to 0.72) and the composite of death or MI (13.5% vs. 17.4%; p < 0.01; HR: 0.74, CI: 0.66 to 0.84), but not MI alone (6.7% vs. 7.2%; p = 0.30; HR: 0.93, CI: 0.78 to 1.11), compared with nonusers of clopidogrel. The association between clopidogrel use and the composite of death or MI was significant only among patients presenting with NSTEMI (HR: 0.67; CI: 0.59 to 0.76; pint < 0.01), not among those presenting with UA (HR: 1.25; CI: 0.94 to 1.67).
Conclusions:
In a large, community-based cohort of patients who were medically managed after UA/NSTEMI, clopidogrel use was associated with a lower risk of death and MI, particularly among patients with NSTEMI.
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