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Cascade Testing for Dilated Cardiomyopathy Likely to Be Cost Effective, Analysis Finds

NEW YORK (GenomeWeb) – Cascade testing of asymptomatic relatives of patients with dilated cardiomyopathy appears to be cost effective, according to a new analysis.

Dilated cardiomyopathy is a common cause of heart failure and has been linked to variants within numerous genes, such as TNb, LMNA, and MYH7. Genetic testing, though, is currently not recommended by many worldwide guidelines for all patients with dilated cardiomyopathy or their relatives, unless they have significant cardiac conduction disease or a family history of premature, unexpected sudden death.

Without genetic testing, family members of people suspected of having familial dilated cardiomyopathy instead are recommended to undergo periodic clinical surveillance.

A team led by researchers at the University of Melbourne examined whether cascade genetic testing might be a cost-effective approach. As they reported in Genetics in Medicine this week, they built a model to assess the cost effectiveness of combined cascade testing and periodic clinical surveillance of asymptomatic relatives of patients with dilated cardiomyopathy versus surveillance alone.

"Using cascade genetic testing to guide clinical surveillance of asymptomatic relatives of patients with [dilated cardiomyopathy] is very likely to be cost effective," Ilias Goranitis, a health economics researcher the University of Melbourne, and his colleagues wrote in their paper.

For their analysis, the researchers constructed a decision-analytic model that combined a decision tree and a Markov model. The decision tree mapped out the choices a relative of a proband with dilated cardiomyopathy has to make, such as whether to accept or decline cascade screening or surveillance, both before and after testing of their relative. The model further assumed that only a portion of asymptomatic relatives — about 40 percent — would commit to cascade testing, in line with published evidence.

The Markov model, meanwhile, simulated the natural history of the disease — in which relatives with a pathogenic variant first started out asymptomatic but then progressed to have preclinical or mild dilated cardiomyopathy, dilated cardiomyopathy, or died.

Additionally, the model assumed that familial dilated cardiomyopathy occurs in 35 percent of idiopathic cases and that 17.5 percent of this modeled cohort of first-degree relatives was expected to have a monogenic cause of dilated cardiomyopathy. Further, based on diagnostic rates, which are about 14 percent, it further assumed that about 7 percent of first-degree relatives would have an identifiable disease variant.

At the same time, the researchers estimated the cost of testing or surveillance within the Australian healthcare system. They calculated the cost of exome sequencing with analysis of up to 100 genes in the proband to be A$1,200 (US$865) and associated initial and follow-up genetic counseling costs to be $184 and $147, respectively. Cascade genetic testing of a relative, meanwhile, costs $250 with the same genetic counseling costs. In all, they expected the addition of genetic testing to result in costs of $3,600 per relative.

That, they noted, is about $300 more than the expected cost for period clinical surveillance — encompassing a consultation with a cardiologist, electrocardiography, and echocardiography every two years.

Still, they reported that cascade genetic testing is likely to be cost effective. Using cascade genetic testing to guide clinical surveillance also led to approximately 15 quality-adjusted life years (QALY), a common quality of life measure, per first-degree relative, slightly more than clinical surveillance alone. In all, they estimated the incremental cost per QALY for cascade genetic testing, as compared to periodic clinical surveillance alone, to be about $6,100 for first-degree relatives. This, they noted, is below the established $40,000 to $70,000 threshold for cost effectiveness.

The finding that cascade genetic testing is cost effective suggested to the researchers that it could be more widely offered to patients beyond the current guidelines. "This has important implications for the evaluation of [dilated cardiomyopathy] and suggests that those with a family history of the condition should have improved access to specialized cardiac genetic services," the researchers wrote.