New retrospective studies of prasugrel vs. clopidogrel presented at TCT

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Daiichi Sankyo and Eli Lilly and Company have announced new results of two retrospective, observational, comparative effectiveness studies of US hospital data comparing rates of readmission for subsequent heart attack and initial hospitalisation costs among patients with acute coronary syndromes (ACS) treated with a percutaneous coronary intervention (PCI) and antiplatelet therapy, including prasugrel (Effient) or clopidogrel (Plavix). The findings were presented at the TCT congress. 

The first study evaluated the rate of rehospitalisation for acute myocardial infarction (AMI) and bleeding at both 30- and 90-days after discharge for ACS-PCI patients treated with prasugrel compared to clopidogrel. Based on a cohort of 83,567 ACS-PCI patients in the PREMIER database, prasugrel-treated patients (n=9,404) had a significantly lower adjusted rate of rehospitalisation for AMI than clopidogrel-treated patients (n=74,163) at 30 days (Odds Ratio [OR]: 0.89; p=0.047) and 90 days (OR: 0.90; p= 0.037) following ACS-PCI discharge. The adjusted rates of bleeding-related rehospitalisation were not different between prasugrel- and clopidogrel-treated patients at 30 days (OR: 1.04; p=0.82) or 90 days (OR: 0.92; p=0.51) post-discharge. In the pivotal randomised control trial, TRITON-TIMI 38, the risk of serious bleeding was significantly higher with prasugrel versus clopidogrel (2.2% versus 1.7%, respectively).


The second study evaluated use of healthcare resources by prasugrel-treated ACS-PCI patients compared to clopidogrel-treated patients during index hospitalisation (hospitalisation that qualified the patients for entry into the study), as measured by hospital costs. Based on a cohort of 84,695 ACS-PCI patients in the PREMIER database, adjusted estimates of average hospitalisation costs for patients receiving clopidogrel (n=75,224) or prasugrel (n=9,471) were US$17,519 (+ or – US$2,548) and US$17,139 (+ or – US$2,560) respectively – a cost savings of US$380 (p<0.05) for prasugrel-treated patients during the index hospital stay. Results were consistent across subgroups by subtype of ACS (STEMI, NSTEMI, and unstable angina).   


“In the current healthcare environment, it is important to understand the comparative effectiveness of antiplatelet therapies on re-hospitalisation rates for subsequent events, such as heart attacks, and index hospitalisation costs associated with their use in the real-world setting,” said lead study investigator Jay P Bae, health economist, Health Outcomes Research, Global Health Outcomes, Eli Lilly and Company. “The findings of these studies expand on data from clinical studies and previous health outcomes research.”


The studies were conducted using the PREMIER Perspective Database, a large US database of drug utilisation and other aggregate hospital data on more than 45 million inpatient discharges and 210 million hospital outpatient visits from US acute care facilities, ambulatory surgery centres and clinics. The PREMIER Perspective Database has been selected by the Centers for Medicare & Medicaid Services for measurement of hospital quality and is commonly used for outcomes research including studies published in top medical journals. The data presented at TCT evaluated non-randomised ACS-PCI patients hospitalised between July 2009 and June 2011. The study endpoints were pre-specified and the analyses were blinded and conducted by the PREMIER research team. The studies included ACS-PCI patients treated with prasugrel who were on label or clopidogrel-treated patients who would have been eligible for prasugrel treatment per the US prescribing information (i.e., patients who fit the description of the indication in the US FDA-approved Effient label).


“The results from the PREMIER studies provide physicians with real-world insights into the use and effectiveness of Effient in ACS-PCI patients in the United States,” said Xin Ye, director, Health Economics & Outcomes Research, Daiichi Sankyo.


This study was adjusted for potential selection bias, including the following variables: patient age, sex, race, type of ACS diagnosis, comorbidities and details of intervention.


Assessment of observed rates of 30- and 90-day re-hospitalisation for AMI and bleeding in patients with ACS-PCI: Comparison of prasugrel and clopidogrel


The observed rates of 30- and 90-day re-hospitalisation due to AMI and 30- and 90-day bleeding-related re-hospitalisation rates among ACS-PCI patients treated with prasugrel or clopidogrel in a real-world US hospital setting were also presented at TCT. At 30-days, the unadjusted AMI-related re-hospitalisation rates were significantly lower for prasugrel as compared to clopidogrel (3.9% and 4.7%, respectively; p<0.05). At 90-days, the unadjusted AMI-related re-hospitalisation rates were significantly lower for prasugrel as compared to clopidogrel (5.1% and 6.3%, respectively; p<0.05).


The unadjusted bleeding-related re-hospitalisation rate was 0.5% in prasugrel-treated patients compared to 0.8% in clopidogrel-treated patients at 30-days (p<0.05) and 0.8% in prasugrel-treated patients compared to 1.4 percent in clopidogrel-treated patients at 90-days (p<0.05) post-discharge.


Observed mean length of stay, hospitalisation costs and bleeding rates of ACS-PCI: Comparison of prasugrel and clopidogrel


The goal of this analysis was to compare observed mean length of stay, total costs and bleeding rates associated with the index hospitalisation – hospitalisation that qualified the patients for entry into the study – for ACS-PCI patients treated with prasugrel or clopidogrel. Across the entire study population, the unadjusted mean length of stay was 2.9 + or – 2.4 days for prasugrel-treated patients as compared to 3.5 + or – 4.4 days for clopidogrel-treated patients (p<0.05).  The actual observed mean hospitalisation costs for prasugrel-treated patients were US$16,199 + or – US$10,054 compared to US$17,647 + or – US$16,696 for clopidogrel-treated patients (p<0.05).


In the study, unadjusted rates of bleeding (defined as the presence of bleeding ICD-9 codes) were 2.2% and 3.3% in prasugrel- and clopidogrel-treated patients, respectively (p<0.05).


Unadjusted rates of transfusion were 1.2% and 3.1% in prasugrel- and clopidogrel-treated patients, respectively (p<0.05). Unadjusted rates of bleeding or transfusion were 3.2% and 5.7% in prasugrel- and clopidogrel-treated patients, respectively (p<0.05).


In the pivotal randomised control trial, TRITON-TIMI 38, the risk of serious bleeding was significantly higher with prasugrel versus clopidogrel (2.2% vs. 1.7%, respectively).

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