Warfarin Genotyping Reduces Hospitalization Rates Results From the MM-WES (Medco-Mayo Warfarin Effectiveness Study)

ObjectivesThis study was designed to determine whether genotype testing for patients initiating warfarin treatment will reduce the incidence of hospitalizations, including those due to bleeding or thromboembolism.BackgroundGenotypic variations in CYP2C9and VKORC1have been shown to predict warfarin dosing, but no large-scale studies have prospectively evaluated the clinical effectiveness of genotyping in naturalistic settings across the U.S.MethodsThis national, prospective, comparative effectiveness study compared the 6-month incidence of hospitalization in patients receiving warfarin genotyping (n = 896) versus a matched historical control group (n = 2,688). To evaluate for temporal changes in the outcomes of warfarin treatment, a secondary analysis compared outcomes for 2 external control groups drawn from the same 2 time periods.ResultsCompared with the historical control group, the genotyped cohort had 31% fewer hospitalizations overall (adjusted hazard ratio [HR]: 0.69, 95% confidence interval [CI]: 0.58 to 0.82, p < 0.001) and 28% fewer hospitalizations for bleeding or thromboembolism (HR: 0.72, 95% CI: 0.53 to 0.97, p = 0.029) during the 6-month follow-up period. Findings from a per-protocol analysis were even stronger: 33% lower risk of all-cause hospitalization (HR: 0.67, 95% CI: 0.55 to 0.81, p < 0.001) and 43% lower risk of hospitalization for bleeding or thromboembolism (HR: 0.57, 95% CI: 0.39 to 0.83, p = 0.003) in patients who were genotyped. During the same period, there was no difference in outcomes between the 2 external control groups.ConclusionsWarfarin genotyping reduced the risk of hospitalization in outpatients initiating warfarin. (The Clinical and Economic Impact of Pharmacogenomic Testing of Warfarin Therapy in Typical Community Practice Settings [MHSMayoWarf1]; NCT00830570

Comparative Effectiveness Research and Personalized Medicine: Catalyzing or Colliding?

Comparative effectiveness research (CER) is generating intense attention as interest grows in finding new and better drug technology assessment processes. The federal government is supporting the expansion of CER through funding made available in the American Recovery and Reinvestment Act of 2009 (ARRA) and by establishing the Patient-Centered Outcomes Research Institute through the Patient Protection and Affordable Care Act of 2010. At the same time, personalized medicine is generating debate about its place in clinical medicine, and so, naturally, how CER can or cannot play a role in personalized medicine is part of these debates. At the heart of the debate around the role of CER in personalized medicine is the nature of personalized medicine and how it fits within contemporary clinical research concepts. We maintain in this article that CER can serve to catalyze personalized medicine, but we recognize that, for this to happen, researchers will need to embrace new data sources and new analytic approaches. We also recognize that drug technology assessment processes will have to undergo necessary adaptations to accommodate CER as configured for personalized medicine, and that clinicians will need to be educated appropriately and provided access to decision-support systems through health information technology to use the information coming from this research. To illustrate our argument, we describe two ongoing CER studies funded and managed in the private sector evaluating personalized medicine interventions that have important clinical and financial implications. One of the studies investigates the clinical and financial effects of pharmacogenomic testing for warfarin as prescribed in conditions of typical practice settings. The other study is also set in community practice settings and compares cardiovascular outcomes of patients receiving clopidogrel who are extensive metabolizer phenotypes for the cytochrome P450 2C19 hepatic isoenzyme with all patients receiving prasugrel.clinical-genetics, decision-making, formularies, treatment-outcome