A cross-validation of risk-scores for coronary heart disease mortality based on data from the Glostrup Population Studies and Framingham Heart Study

BACKGROUND: Due to marked regional differences in the incidence of coronary heart disease (CHD) in Europe, the recommendation by the European Society of Cardiology to use the Coronary Risk Chart based on data from the Framingham Heart Study, could be questioned. METHODS: Data from two population studies (The Glostrup Population Studies, n = 4757, the Framingham Heart Study, n = 2562) were used to examine three different levels of cross-validation. The first level of examination was whether a risk-score developed from one sample adequately ordered the risk of participants in the other sample, using the Area Under a Receiver Operating Characteristic (AUROC) curve. The second level compared the magnitude of coefficients in logistic models in the two studies; while the third level tested whether the level of risk of CHD death in one sample could be estimated based on a risk function from the other sample. RESULT: Coronary heart disease mortality was 515 per 100 000 person-years in Framingham and 311 per 100 000 person-years in Glostrup. The AUROC curve was between 75% and 77% and regardless of which risk-score was used. Logistic coefficients did not differ significantly between studies. The Framingham risk-score significantly overestimated the risk in the Glostrup sample and the Glostrup risk-score underestimated in the Framingham sample. CONCLUSION: Using this Framingham risk-score on a Danish population will lead to a significant overestimation of coronary risk. The validity of risk-scores developed from populations with different incidence of the disease should preferably be tested prior to their application.