Dataset Produces Different Results on Safety, Effectiveness of Effient vs Plavix

Safety and effectiveness analyses comparing the antiplatelets Effient (prasugrel; Daiichi Sankyo) and Plavix (clopidogrel;  Sanofi) after percutaneous coronary intervention (PCI) demonstrated different findings depending on the analytic technique used. 

The findings were published in JAMA Cardiology. 

“Conclusions regarding the safety and efficacy of antiplatelet therapy varied depending on analytic technique,” researchers reported, “and none were concordant with the results from randomized trials.” 

For the study, researchers used observational data from the Treatment with Adenosine Diphosphate Receptor Inhibitors–Longitudinal Assessment of Treatment Patterns and Events After Acute Coronary Syndrome (TRANSLATE-ACS) study. The investigation included 11,784 patients who underwent PCI for myocardial infarction. Twenty-six percent received prasugrel.

When researchers used propensity risk adjustment, both prasugrel and clopidogrel had similar rates of major adverse cardiovascular events and bleeding outcomes. The rate of stent thrombosis was lower with prasugrel, according to the study.

However, instrumental variable methods linked prasugrel with a lower rate of major adverse cardiovascular events. Rates of bleeding and stent thrombosis were similar with the 2 antiplatelets, researchers reported. 

Meanwhile, falsification analyses showed likely false relationships between prasugrel and orthopedic fracture (approaching statistical significance), using propensity score analyses, and pneumonia-related hospitalizations, using instrumental variable methods, according to the study.

“These differences may represent persistent bias in the comparison of the prasugrel and clopidogrel populations that both methods failed to completely control,” the researchers wrote. “Alternatively, it may also represent a difference in the performance of prasugrel when evaluated outside of a randomized clinical trial in real-world populations, and in this sense, randomized trial data are an imperfect criterion standard for comparison of the results from observational studies.” 

They concluded: “A high level of scrutiny and careful attention to assumptions and validity are required when interpreting complex analyses of observational data.”—Jolynn Tumolo