External validation of QDSCORE(®) for predicting the 10-year risk of developing Type 2 diabetes.
BACKGROUND
A small number of risk scores for the risk of developing diabetes have been produced but none has yet been widely used in clinical practice in the UK. The aim of this study is to independently evaluate the performance of QDSCORE(®) for predicting the 10-year risk of developing diagnosed Type 2 diabetes in a large independent UK cohort of patients from general practice.


METHODS
A prospective cohort study of 2.4 million patients (13.6 million person years) aged between 25 and 79 years from 364 practices from the UK contributing to The Health Improvement Network (THIN) database between 1 January 1993 and 20 June 2008.


RESULTS
QDSCORE(®) showed good performance data when evaluated on a large external data set. The score is well calibrated with reasonable agreement between observed and predicted outcomes. There is a slight underestimation of risk in both men and women aged 60 years and above, although the magnitude of underestimation is small. The ability of the score to differentiate between those who develop diabetes and those who do not is good, with values for the area under the receiver operating characteristic curve exceeding 0.8 for both men and women. Performance data in this external validation are consistent with those reported in the development and internal validation of the risk score.


CONCLUSIONS
QDSCORE(®) has shown to be a useful tool to predict the 10-year risk of developing Type 2 diabetes in the UK.