Impact of the reporting source on Platelet Inhibition and Treatment Outcomes (PLATO) trial deaths.

Abstract

Background: Platelet Inhibition and Clinical Outcomes (PLATO) was a multicenter, randomized double-blind trial assessing efficacy and safety of ticagrelor versus clopidogrel in patients with acute coronary syndrome. The reported mortality benefit of ticagrelor in the PLATO trial has been challenged for over decade, and never confirmed in later trials.

Objective: To compare if there were any differences when deaths were reported to the FDAby the sponsors or by independent Contract Research Organizations (CRO).

Methods: We obtained the complete PLATO deaths dataset reported to the FDA and revealed that some events were inaccurately reported favoring ticagrelor. The entire FDA list contains precisely detailed 938 PLATO deaths. The CRO reported outcomes from the USA, Russia, Georgia, and most of Ukraine, while sites in 39 other countries were controlled by the trial sponsors. We compared vascular- (code "11"), non-vascular- (code "12"), and unknown (code "97") deaths triaged by the reporting source.

Results: Overall, most PLATO deaths were vascular (n=677), less non-vascular (n=159) andunexpectedly many of "other" (n=7) or "unknown" (n=95) origin reported either by sponsors (n=807) or CRO (n=131). The trial sponsors reported more clopidogrel deaths from vascular (313 vs.239), non-vascular (86 vs.58) and unknown (53 vs. 26) causes.In contrast, CRO-monitored sites reported significantly (72 vs. 53; p<0.01) more ticagrelordeaths than after clopidogrel from vascular (51 vs.39), non-vascular (8 vs.7) and unknown (10 vs. 4) causes.

Conclusion: Deaths were reported differently by sponsors and CRO within the same trial. Since some deaths were misreported by PLATO sponsors, only the CRO data seems mostly reliable. Among all countries, the CRO - reported PLATO-USA outcomes represent the largest and most realistic dataset of realistic evidence suggesting ticagrelor inferiority to clopidogrel for all primary endpoint components including vascular death.