Indirect estimation of the comparative treatment effect in pharmacogenomic subgroups

Impact of SLCO1B1 Pharmacogenetic Testing on Patient and Healthcare Outcomes: A Systematic Review

Demonstrated improvements in patient outcomes will facilitate the clinical implementation of pharmacogenetic testing. Using the association between solute carrier organic anion transporter family member 1B1 (SLCO1B1) and statin-associated muscle symptoms (SAMSs) as a model, we conducted a systematic review of patient outcomes after delivery of SLCO1B1 results. Using PubMed and Embase searches through December 19, 2017, we identified 37 eligible records reporting preliminary or final outcomes, including six studies delivering only SLCO1B1 results and five large healthcare system-based implementation projects of multipharmacogene panels. Two small trials have demonstrated at least short-term improvements in low-density lipoprotein cholesterol after SLCO1B1 testing among previously statin intolerant patients. Evidence from large implementation projects suggests that SLCO1B1 results may change prescribing patterns for some high-risk patients. No study has reported improvements in SAMSs or cardiovascular events or tracked the economic outcomes of SLCO1B1 testing. Ongoing studies should collect and report outcomes relevant to pharmacogenetics stakeholders.

Financial Analysis of CYP2C19 Genotyping in Patients Receiving Dual Antiplatelet Therapy Following Acute Coronary Syndrome and Percutaneous Coronary Intervention

BACKGROUND

Dual antiplatelet therapy is an established standard of care for patients with acute coronary syndrome (ACS) to reduce thrombotic risk. Reduced CYP2C19 activity impairs clopidogrel bio-activation and increases risk of adverse clinical outcomes. Patients with poor and intermediate CYP2C19 metabolizers treated with clopidogrel incur higher cardiovascular event rates, including myocardial infarction, stroke, and stent thrombosis, following ACS than patients with normal CYP2C19 function. Tests are available to identify the CYP2C19 genotype and can be used to support individualization of antiplatelet therapy. 

OBJECTIVE

To estimate the financial impact of CYP2C19 genotyping in a theoretical cohort of 1,000 patients with ACS, who received percutaneous coronary intervention and coronary stent implantation and were treated with clopidogrel, prasugrel, or ticagrelor in a managed care setting. 

METHODS

Differences in overall and average cost per patient were estimated based on the rate of CYP2C19 genotyping in a theoretical cohort of 1,000 patients. Sensitivity analysis was carried out for varying costs, adherence, and the percentage of patients treated according to genotyping results. All clinical event costs were reported in terms of 2012 U.S. dollars. The budget impact analysis used published event rates from primary literature to estimate costs of events analysis for 3 different scenarios: Scenario A, no CYP2C19 genotyping; Scenario B, 50% of patients received CYP2C19 genotyping with appropriate treatment based on genotype; and Scenario C, 100% of patients received CYP2C19 genotyping with appropriate treatment based on genotype. 

RESULTS

According to this model, there was no change in the market share for the 3 antiplatelet agents in Scenario A. Initial market share for clopidogrel, prasugrel, and ticagrelor was 93%, 5%, and 2%, respectively; however, use of CYP2C19 genotyping is expected to shift market share from clopidogrel to either prasugrel or ticagrelor. In Scenario B, where 50% of the patients received genotyping, clopidogrel market share was reduced to 83%, while prasugrel increased to 12.1% and ticagrelor increased to 4.9%. In Scenario C, where all patients received genotyping, clopidogrel market share was reduced to 73%, prasugrel increased to 19.3%, and ticagrelor increased to 7.7%. Total estimated cost differences when all possible patients were genotyped included annual savings of roughly $444,852.

CONCLUSIONS

Important financial benefits may be realized through use of genotype-guided antiplatelet therapy to reserve prasugrel or ticagrelor use for patients with reduced CYP2C19 activity to avoid costs associated with adverse cardiac events.

Cost–effectiveness of using CYP2C19 genotype to guide selection of clopidogrel or ticagrelor in Australia

Aims: This study aims to assess the cost–effectiveness in Australia of screening CYP2C19 loss-of-function (LoF) alleles to guide selection of clopidogrel or ticagrelor for individuals with acute coronary syndrome who are likely to undergo coronary stenting. Methods: Three treatment strategies were compared: universal clopidogrel therapy, universal ticagrelor therapy and genotyping CYP2C19 with use of ticagrelor for individuals with a LoF allele and clopidogrel for individuals without a LoF allele. Lifetime costs and quality-adjusted life years for each treatment strategy were estimated using a Markov model. The risks of events were primarily derived from the genetic substudy of the pivotal randomized controlled trial. Results: CYP2C19 genotyping resulted in greater effectiveness and was cost-effective when compared with universal use of clopidogrel. However, universal use of ticagrelor was the most effective strategy overall and the incremental cost–effectiveness compared with the genotyping strategy was generally within what is considered acceptable. Conclusion: Ticagrelor is likely to be cost-effective even for individuals not carrying a CYP2C19 LoF allele.

Original submitted 30 May 2013; Revision submitted 16 August 2013