- Genomic Data Collaboration to Aid Precision Medicine, Drug Discovery
- Study to Advance Precision Medicine for Cardiovascular Disease
Over 30 percent of people have loss-of-function variants in the CYP2C19 gene that decreases the effectiveness of clopidogrel. These patients may not get the full benefit of clopidogrel, which would increase their risk of MACE. The FDA recommends that providers consider different treatments for these individuals, such as prasugrel or ticagrelor, to replace clopidogrel.
In 2018, UAB and researchers at nine universities across the US showed that patients with loss-of-function variants who were treated with clopidogrel had elevated risks. The study revealed that there was a twofold risk of MACE in PCI patients, and a threefold risk for MACE among patients with acute coronary syndrome who received PCI, as compared to patients prescribed prasugrel or ticagrelor instead of clopidogrel.
While prasugrel and ticagrelor are not influenced by loss-of-function variants and can substitute for clopidogrel, these drugs are much more costly and can bring a higher risk of bleeding.
Using this real-world data, the research team set out to conduct an economic analysis of the best treatments for heart disease patients. The study compared three main strategies: treating all patients with clopidogrel, treating all patients with ticagrelor, and genotyping all patients and using ticagrelor in those with loss-of-function variants.
The group considered differences in event rates for heart attacks and stent thrombosis in patients receiving clopidogrel versus ticagrelor versus genotype-guided therapy, during the one-year period following PCI. They also considered medical costs from events like admissions, procedures, medications, clinical visits, and genetic testing. The study used an economic measure known as the quality-adjusted life year (QALY).
“First, we looked at which strategy provided the highest QALY,” Limdi said. “The QALY is the gold standard for measuring benefit of an intervention — in our case, genotype-guided treatment compared to treatment without genotyping. Universal ticagrelor and genotype-guided antiplatelet therapy had higher QALYs than universal clopidogrel — so those are the best for the patient.”
Researchers then analyzed whether those interventions that have higher QALYs were also reasonable from a cost perspective, which includes a payer’s or patient’s willingness to pay.
“In our case, the payor would recognize that ticagrelor is more expensive than clopidogrel — $360 per month vs. $10 per month — and there is a $100 cost for each genetic test,” Limdi said. “So, from the payor perspective, the more effective strategy (one with a higher QALY) — if more expensive (higher cost) — would have to lower the risks of bad outcomes like heart attacks and strokes for the gains in QALY that are at, or below, the willingness-to-pay threshold.”
A measure called incremental cost-effectiveness ratios (ICERs) assesses the incremental cost of the benefit, or improvement in QALY. In the US, a treatment is considered cost-effective if its associated ICER is at or below the willingness-to-pay threshold of $100,000 per QALY.
“In our assessment, the two strategies with the highest QALY had very different ICERs,” Limdi said. “The genotype-guided strategy was cost-effective at $42,365 per QALY. Universal ticagrelor was not; it had an ICER of $227,044 per QALY.”
The study results demonstrate the effectiveness of genotyping and precision medicine strategies for tailoring treatments and improving patient outcomes.
“We showed that tailoring antiplatelet selection based on genotype is a cost-effective strategy,” said Nita Limdi, PharmD, PhD. “Support is now growing to change the clinical guidelines, which currently do not recommend genotyping in all cases. Evidence like this is needed to advance the field of precision medicine.”
By Jessica Kent