Longer duration of clopidogrel use was associated with a lower incidence of death or MI in both the bare-metal stents (BMS) and drug-eluting stents (DES) groups, and the incidence of death or MI did not differ by stent type in clopidogrel nonusers, according to study results in the June 10 issue of the Journal of American College Cardiology.
Somjot S. Brar, MD, from the Columbia University Medical Center in New York City, and colleagues conducted the observational study to determine whether long-term clinical outcomes differed between BMS and DES by duration of clopidogrel use among diabetic patients.
The researchers identified 749 patients with diabetes mellitus who underwent stent implantation with either BMS (251 patients) or DES (498 patients) from October 2002 to December 2004. They performed survival analysis on the full cohort and on those event-free from death, MI or repeat revascularization at six months (671 patients).
By clopidogrel duration, the investigators found that the event rate for death or MI was 3.2 percent in the greater than nine-month group, 9.4 percent in the six- to nine-month group and 16.5 percent in the less than six-month group.
For death alone, the event rate was 0.5 percent in the greater than nine-month group, 4.3 percent in the six- to nine-month group and 10 percent in the less than six-month group, according Brar and colleagues.
When taking BMS clopidogrel non-users as a referent in the multivariate analysis, the investigators observed that the hazard ratio (HR) for death and nonfatal MI for DES clopidogrel users, DES clopidogrel nonusers and BMS clopidogrel users were: HR 0.22, HR 0.39 and HR 0.25, respectively.
The authors wrote that their “observations suggest that the extended use of clopidogrel is associated with a reduction in death or death and nonfatal MI,” which they said is likely to result from the dual action of clopidogrel—the prevention of stent thrombosis and other adverse events.
Because the study contradicts two prior six-month, left-censored survival analyses, the researchers noted that their study “relates specifically to patients with diabetes, whereas in the prior studies the majority of the patients (70 percent to 80 percent) were not diabetic.”
As a result, Brar and colleagues concluded that “the safety and efficacy of DES and the appropriate duration of clopidogrel use in a diabetic population can only be drawn from prospective randomized trials.”
Kaiser Permanente Southern California and Boston Scientific funded the study, but the authors noted that the companies were not involved “in the study design, analysis or interpretation and had no role in the drafting of the manuscript.”