Friday, November 4, 2011

HBA1c Unreliable for Pediatric Screening

From Reuters Health Information By Will Boggs MD NEW YORK (Reuters Health) Oct 26 - Hemoglobin A1c is not a reliable marker of dysglycemia in overweight or obese children and adolescents, researchers say. "Despite the new guidelines recommending the use of hemoglobin A1c for diagnosis of diabetes, it is not as reliable a test for identifying children with diabetes or at high risk for diabetes," lead author Dr. Joyce M. Lee from University of Michigan in Ann Arbor told Reuters Health in an email. She suggests that doctors "consider ordering alternative tests, such as a random glucose or a 1 hour nonfasting glucose tolerance test." Dr. Lee and colleagues compared five nonfasting screening tests in 254 overweight or obese children and adolescents aged 10 to 17 years: HbA1c, urinalysis, fructosamine, a one-hour glucose challenge, and a random blood test. A formal two-hour oral glucose tolerance test showed that 39% of the youngsters had prediabetes and 1.2% had diabetes, according to a report online September 27th in Diabetes Care. Urinalysis had a very low sensitivity (but high specificity) for detecting dysglycemia. On the other tests, higher thresholds provided lower sensitivity and higher specificity, whereas lower thresholds had higher sensitivity but lower specificity. Discrimination was poor for HbA1c and fructosamine levels, as evidenced by relatively low likelihood ratios across test thresholds, as well as by low values for area under the curve (AUC). With random glucose and one-hour glucose challenge tests, however, discrimination was "closer to an acceptable range," the authors said. Both provided substantially higher AUC compared to HbA1c or fructosamine. The researchers say their findings are consistent with other recent studies of HbA1c tests in children. "Either the nonfasting one-hour glucose challenge test or the random glucose represent promising screening tests for use in the pediatric primary care setting, as these are tests that clinicians can easily order the same day of the visit," they conclude. Dr. Lee said she and her colleagues are now trying to learn "whether a clinical risk score based solely on clinical characteristics" would help screen children for diabetes. "This would be a convenient and cost-effective way to identify high-risk children," she said. SOURCE: Diabetes Care 2011.

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