External validation of non-invasive diabetes score in a 15-year prospective study

A novel scoring system called Non-invasive Diabetes Score (NDS) was developed. The model showed prominent discrimination and calibration in the original study population. However, before a new model could be adopted in clinical practice and acquire widespread use, it is necessary to confirm that it also performs well in external validations in different settings of people. The aim of this study was to investigate whether the novel user-friendly score predicting diabetes mellitus (DM) could have satisfying performance in predicting DM in Southwest China in a 15-year prospective cohort study.

This prospective cohort study was carried out based on a general Chinese population of 711 individuals from 1992 to 2007. We excluded 24 of them at baseline because they were diabetics. The end point was DM, and the risk was calculated using the model formula.

During a follow-up of 15 years, 74 (10.77%) patients reached the end point. Evaluation of this model in our cohort, with Harrell's C-index of 0.662 (95% CI: 0.600-0.723) for the whole cohort and 0.695 (95% CI: 0.635-0.756) in sensitivity analysis, indicated the possibly helpful discrimination. The calibration capability in our cohort was useful that the observed incidence of diabetes mellitus was near the predicted.

Our external validation suggested NDS had possibly helpful discrimination and satisfying calibration for predicting DM during 15-year follow-up.