This article is more than 5 years old. Information may no longer be current.
Results of antiplatelet therapies after PCI vary by statistical method
Data on safety and efficacy of antiplatelet therapy after PCI varied depending on analytic technique, highlighting the importance of randomized trials, according to a study published in JAMA Cardiology.
Researchers compared safety and efficacy outcomes of prasugrel (Effient, Daiichi Sankyo/Eli Lilly) vs. clopidogrel bisulfate after PCI using two analytic techniques: inverse probability of treatment weighting adjustment and instrumental variable methods.
Jerome J. Federspiel, MD, PhD, and colleagues used data from 11,784 patients (mean age, 60 years; 28% women) from the TRANSLATE-ACS study from April 2010 to October 2012. Patients undergoing PCI for MI were included, and 26% of them received prasugrel.
Researchers found that, using inverse of probability of treatment weighting adjustment, prasugrel and clopidogrel had similar MACE (HR = 0.98; 95% CI, 0.83-1.16) and bleeding outcomes (HR = 1.18; 95% CI, 0.77-1.8), but prasugrel was associated a lower rate of stent thrombosis (HR = 0.51; 95% CI, 0.31-0.85).
When Federspiel, from Duke Clinical Research Institute at Duke University Medical Center, and colleagues performed an analysis using instrumental variable methods, use of prasugrel was associated with a lower rate of MACE (HR = 0.68; 95% CI, 0.47-1), but there were insignificant differences in bleeding rates (HR = 0.95; 95% CI, 0.41-2.08) and stent thrombosis (HR = 0.67; 95% CI, 0.16-2).
No significant treatment difference was noted in any of the falsification endpoint rates when analyses were performed using inverse probability of treatment weighting, although a bone fracture endpoint did near statistical significance. When using instrumental variable methods, a lower rate of pneumonia-related hospitalizations was shown in patients treated with prasugrel, according to the researchers.
“The comparative safety and efficacy conclusions varied depending on whether an [inverse probability of treatment weighting] or [instrumental variable] approach was used,” the researchers wrote. “Neither statistical method produced data that were concordant with the results from randomized clinical trials.”
Gregg C. Fonarow, MD, from Ronald Reagan UCLA Medical Center, wrote in a related editorial, “There has been substantial and growing interest in using observational data for comparing the outcomes and safety of different therapies in actual clinical practice and in broader cohorts of patients. Because treatment is not assigned at random, these comparisons are subject to various biases and [thus] confounding.
Gregg C. Fonarow
“Greater emphasis could be placed on reducing restrictive entry criteria and better ensuring that patient populations now underrepresented are enrolled in randomized clinical trials to determine to efficacy and safety for these clinically relevant subgroups,” Fonarow wrote. – by James Clark
Disclosure: The TRANSLATE-ACS study was funded by Daiichi Sankyo and Lilly USA. Federspiel reports no relevant financial disclosures. Please see the full study for a list of the other researchers’ relevant financial disclosures. Fonarow reports consulting for Janssen Pharmaceuticals and Novartis.