Comparative effectiveness of clopidogrel in medically managed patients with unstable angina and non-ST-segment elevation myocardial infarction.
OBJECTIVE
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.
Division of Research, Kaiser Permanente Northern California, Oakland, California; Stanford University School of Medicine, Stanford, California. Electronic address: Matthew.D.Solomon@kp.org.
Matthew D
MD
Solomon
Division of Research, Kaiser Permanente Northern California, Oakland, California; Stanford University School of Medicine, Stanford, California; University of California, San Francisco, San Francisco, California.
Alan S
AS
Go
Stanford University School of Medicine, Stanford, California.
David
D
Shilane
Stanford University School of Medicine, Stanford, California.
Derek B
DB
Boothroyd
Division of Research, Kaiser Permanente Northern California, Oakland, California.
Thomas K
TK
Leong
University of California, San Francisco, San Francisco, California; San Francisco General Hospital, San Francisco, California.
Dhruv S
DS
Kazi
Stanford University School of Medicine, Stanford, California.
Tara I
TI
Chang
Stanford University School of Medicine, Stanford, California.
Mark A
MA
Hlatky
D000368:Aged; D000789:Angina, Unstable / Q000175:diagnosis* / Q000188:drug therapy* / Q000453:epidemiology; D000077144:Clopidogrel; D015331:Cohort Studies; D019468:Disease Management; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000188:drug therapy* / Q000453:epidemiology; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use*; D012189:Retrospective Studies; D013988:Ticlopidine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D016896:Treatment Outcome
D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine
acute coronary syndrome(s); clopidogrel; outcomes