VALUE OF HEMOGLOBIN A1c IN DIAGNOSING DIABETES MELLITUS WITHIN A CHRONIC DISEASE MANAGEMENT SYSTEM ILLUSTRATED BY THE RECEIVER OPERATING CHARACTERISTIC CURVE

Objective: To develop a receiver operating charcteristic (ROC) curve of glycosylated hemoglobin (HbA(Is)) for diagnosing diabetes mellitus within a chronic disease management system. Methods: A case-control study including medical records from January 1, 1997, to December 31, 2005, was conducted at the Sioux Falls Veterans Affairs Medical Center Medical records for the case group (patients with diabetes) were selected based on 1 of 3 criteria International Classification of Diseases, Ninth Revision, Clinical Modification or Current Procedural Terminology codes specific for type 1 and type 2 diabetes, patients' use of medication (oral hypoglycemic agents, antidiabetes agents, or insulin), or results from random blood glucose >= 200 mg/dL) Records for the control group were selected based on patients having HbA(Is) measured, but not meeting the above diagnostic criteria for diabetes during the study period Records for cases and controls were randomly frequency-matched, one-to-one The control groups was randomly dividied into 5 sets of an equal number of records Five sets of an equal number of cases were then randomly selected from the total number of cases Each tech data set included 1 case group and 1 control group, resulting in 5 independent data sets Results: In total, 5040 patients records met the case definition in the diabetes registry Records of 15 patients who were prescribed met form in only, but did not meet any other case criteria, were reviewed and excluded after determining the patients were not diabetic. The control group consisted of 5 sets of 616 records each (totaling 3080 records), Thus, each of the 5 independent data sets of 1 case group and 1 control group contained 1232 records The case group was predominantly composed of white men (mean age, 69 years, mean body mass index, 31 kg/m(2)). Demographic data were similar for control patients The ROC curve revealed that a HbA(Ic) > 6.3% (mean +/- 1 SD) offered the most accurate cutoff value for diagnostic type 2 diabetes mellitus, with the following statistical vlaues C statistic, 0.78, sensitivity, 70%, specificity, 85%, and positive likilehood ratio, 4.6 (95% confidence interval 4.2-5.0) Concluion: A HbA(Is) value >= 6.3% may be a useful benchmark for diagnosing diabetes mellitus within a chronic disease management system and may be a useful tool for monitoring high-risk population (Endocr Pract. 2010;16;14-20)