Genetic Screening for MODY Could Be Cost-effective

Miriam E. Tucker

September 17, 2013

Routine genetic testing for maturity-onset diabetes of the young (MODY) could be cost-effective or even save money, depending on the price of the test and the prevalence of MODY in the population screened, a new modeling study has found.

The most prevalent form of monogenic diabetes, MODY is typically diagnosed before the age of 25 years. The various MODY genetic types together account for about 1% to 2% of all diabetes cases but are often misdiagnosed as either type 1 or type 2 diabetes, resulting in overtreatment or unnecessary therapy.

Genetic screening is not typically covered even for the 50% of patients who meet classic MODY criteria and is therefore not typically practiced, explain Rochelle N. Naylor, MD, from the University of Chicago and colleagues, who report their findings online September 11 in Diabetes Care.

"Currently, there is no uniform policy on insurance-coverage decisions for MODY genetic testing. Valuation of MODY genetic testing may help inform and shape coverage policies, and our modeled study is a first step in this process," she and her colleagues write.

The findings suggest that genetic screening could be cost-effective if performed among patients who are clinically diagnosed with diabetes but who don't have metabolic features and even cost-saving if performed in patients with classic MODY criteria, the authors say.

Scenarios Do Exist Where ICER Is $50,000 per QALY

The authors modeled the impact of a policy of routine genetic testing for the 3 most common heterozygous MODY gene mutations — glucokinase (GCK )-MODY, hepatocyte nuclear factor 1 homeobox alpha (HNF1A)-MODY, and hepatocyte nuclear factor 4 alpha (HNF4A)-MODY — in a hypothetical population of newly diagnosed patients aged 25 to 40 presumed to have type 2 diabetes under a policy of no testing.

Costs and outcomes of the usual care these patients would have received for type 2 diabetes had the genetic testing not been done were compared with the scenario of testing to obtain the correct diagnosis and appropriate treatment: sulfonylurea pills in the case of HNF1A-MODY and HNF4A -MODY and no treatment at all for GCK-MODY, a mild, nonprogressive phenotype that is not associated with increased risks for microvascular or macrovascular complications.

For the model, assumptions about complication rates and clinical parameters were obtained from the literature. The cost of genetic testing for the 3 mutations was set at $2580 per person. The annual costs of treatment with insulin only, pills/noninsulin injectables, and sulfonylureas were set at $2641, $767, and $96, respectively. The analysis was performed from a healthcare-system perspective over the lifetime of the study population.

Considering health and cost effects together, the genetic screening policy produced an incremental cost-effectiveness ratio (ICER) of $205,000 per quality-adjusted life-year (QALY). An ICER of $50,000/QALY is the usual threshold considered to be cost-effective.

But modeling an increase in MODY prevalence in the screened population from 2% to 6% produced an ICER of just over $50,000/QALY. Similarly, an ICER of $50,000/QALY would also be achieved if the cost of the genetic test were reduced from $2580 to $700, the researchers note.

Screening Cost Saving if Limited to Classic MODY Criteria

And, Dr. Naylor and colleagues determined, if the MODY prevalence in the screened population were 30% or greater, the screening policy would actually cost less than not screening (ie, would become cost saving). This would be the case if screening were limited to those with classic MODY criteria, of whom nearly 50% have 1 of the 3 mutations.

Although the results of modeled data rather than patient cases should be interpreted with caution, they nonetheless "serve as an important indication that MODY genetic testing may improve health outcomes at acceptable societal costs, and thus improved access to testing should be sought," the authors write.

They also note that their model did not account for the effects of identifying family members with MODY, "where testing would occur at a substantially lower cost, nearly 10-fold less, [and] thus, additional cost savings attributable to this 'spillover effect' were not assessed or accounted for, potentially undervaluing the impact of MODY genetic testing.

"As genetic-testing costs decrease over time with advancements in sequencing technology, we can expect generalized screening for subtypes of MODY in type 2 diabetes to be a cost-effective application of personalized genetic medicine," they conclude.

The authors have reported no relevant financial relationships.

Diabetes Care.Published online September 11, 2013.Abstract

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