Researchers Identify Optimal Threshold for HbA1c Test for Prediabetes

Published in the American Journal of Preventive Medicine

San Diego, CA, March 13, 2012 – The American Diabetes Association recommends hemoglobin A1c (HbA1c) testing as one basis for identifying diabetes and prediabetes. Setting a specific HbA1c cutoff threshold for prediabetes, which could be used to determine eligibility for interventions to prevent progression to more serious type 2 diabetes, has generated much debate, with at least three different cutoffs recommended by different professional organizations. A new study led by the Centers for Disease Control and Prevention demonstrates that lowering the cutoff increases the health benefits of preventive interventions, although at higher cost. It concludes that a cutoff level of 5.7% would be cost-effective. The research is published in the April issue of the American Journal of Preventive Medicine.

“Large-scale implementation of evidence-based type 2 diabetes prevention initiatives depends on a clear and efficient strategy to identify individuals at high risk for type 2 diabetes and refer them for intervention. This is the first study to examine the population-level impact and cost effectiveness of using alternative HbA1c cutoffs to determine eligibility for type 2 diabetes preventive interventions,” explains lead investigator Xiaohui Zhuo, PhD, from the Division of Diabetes Translation, Centers for Disease Control and Prevention.

The research team used a simulation model to examine the cost effectiveness associated with each progressive 0.1% decrease in the HbA1c cutoff from 6.4% to 5.5% (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). People identified as having prediabetes were assumed to receive preventive intervention. The study looked at two different interventions: a high cost resource-intensive approach that would cost on average almost $1,000 per year, and a low cost intervention with an annual cost of $300 per year.

Researchers 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 $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. Its use will likely increase as a screening tool to identify those at high risk for type 2 diabetes. “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,” says Dr. Zhuo.

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“Alternative HbA1c Cutoffs to Identify High-Risk Adults for Diabetes Prevention: A Cost-Effectiveness Perspective,” by X. Zhuo, P. Zhang, E. Selvin, T.J. Hoerger, R.T. Ackermann, R. Li, K.M. Bullard, and E.W. Gregg (DOI: 10.1016/j.amepre.2012.01.003). It appears in the American Journal of Preventive Medicine, Volume 42, Issue 4 (April 2012), published by Elsevier.

Notes for editors
Full text of the articles is available to credentialed journalists upon request; contact Beverly Lytton at +1 858 534 9340 oreAJPM@ucsd.edu. Journalists wishing to interview the study authors may contact Laura Baldwin at +1 770 488 5533 or LBZ7@cdc.gov.

About the American Journal of Preventive Medicine
The American Journal of Preventive Medicine (www.ajpm-online.net) is the official journal of The American College of Preventive Medicine (www.acpm.org) and the Association for Prevention Teaching and Research (www.aptrmweb.org). It publishes articles in the areas of prevention research, teaching, practice and policy. Original research is published on interventions aimed at the prevention of chronic and acute disease and the promotion of individual and community health. The journal features papers that address the primary and secondary prevention of important clinical, behavioral and public health issues such as injury and violence, infectious disease, women's health, smoking, sedentary behaviors and physical activity, nutrition, diabetes, obesity, and alcohol and drug abuse. Papers also address educational initiatives aimed at improving the ability of health professionals to provide effective clinical prevention and public health services. The journal also publishes official policy statements from the two co-sponsoring organizations, health services research pertinent to prevention and public health, review articles, media reviews, and editorials.

The American Journal of Preventive Medicine, with an Impact Factor of 4.110, is ranked 10th out of 140 Public, Environmental and Occupational Health titles and 18th out of 151 General & Internal Medicine titles according to the 2010 Journal Citation Reports® published by Thomson Reuters.

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Beverly Lytton
American Journal of Preventive Medicine
+1 858 534 9340
eAJPM@ucsd.edu