Optimal Threshold Identified for Glycated Hemoglobin Test

The measurement of glycated hemoglobin or a hemoglobin A1c (HbA1c) in blood specimens is a stable test for identifying diabetes and prediabetes over several months.

A specific HbA1c cutoff threshold for prediabetes can be used to determine eligibility for interventions to prevent progression to more serious type 2 diabetes and lowering the cutoff increases the health benefits of preventive interventions, although at higher cost.

A study led by the US Centers for Disease Control and Prevention (CDC; Atlanta, GA, USA) used a Markov simulation model to examine the cost effectiveness associated with each progressive 0.1% decrease in the HbA1c cutoff from 6.4% to 5.5% as 6.5% is currently the diagnostic cutoff for diabetes. The simulation used the data of nondiabetic American adults from the National Health and Nutritional Examination Survey (NHANES 1999-2006). The study looked at two different interventions: a high cost resource-intensive approach that would cost on average almost USD 1,000 per year, and a low cost intervention with an annual cost of USD 300 per year.

The scientists measured the cost per each quality-adjusted life year (QALY), a measure of the quality and quantity of life generated by a medical intervention, at each HbA1c cutoff for both interventions. They found that cutoffs of 5.7% and above were cost effective, based on the conventional USD 50,000/QALY cost-effectiveness benchmark. Further, the results suggested that the optimal cutoff may be lower if the cost of preventive interventions could be lowered without compromising effectiveness.

Leading clinical and policy-guiding organizations have recommended the HbA1c as an additional diagnostic tool. The use of this test will probably increase as a screening tool to identify those at high risk for type 2 diabetes. Xiaohui Zhuo, PhD, the lead investigator said, "Therefore, the economic implications of its use need to be well understood. This study will hopefully stimulate more research on the best strategy for optimizing benefits from type 2 diabetes prevention programs at minimum cost." The study is available online in the April 2012 issue of American Journal of Preventive Medicine.

Related Links:
US Centers for Disease Control and Prevention