The external validity and performance of the no-laboratory American Diabetes Association screening tool for identifying undiagnosed type 2 diabetes among the Iranian population

Abstract

AimsThe aim of this study is to assess the American Diabetes Association (ADA) risk score as a self-assessment screening tool for undiagnosed type 2 diabetes (T2DM) in Iran. MethodsIn a national survey of risk factors for non-communicable diseases, we included 3458 Iranian adults. The discrimination and validity were assessed using the area under the curve (AUC), sensitivity, specificity, Youden's index, positive and negative predictive values (PPV and NPV). The frequency of high-risk Iranian population who need a glucose test and those who need intervention were also estimated. ResultsThe AUC was 73.7% and the suggested ADA score of ≥5 yielded a sensitivity of 51.6%, specificity 82.4%, NPV 98.3%, and PPV 7.9%. This threshold results in classifying 18.6% of the Iranians, equals to 8.5 million, as high-risk and 1.5% of the population, about 700,000, would need intervention. However, our study suggested score ≥4 that identified 34% of the population as high-risk and 2% of the population would need intervention. ConclusionOur findings support the ADA suggested threshold for identifying high-risk individuals for undiagnosed T2DM; however, a lower threshold is also recommended for higher sensitivity. The ADA screening tool could help the public health system for low-cost screening.