Framingham risk function overestimates risk of coronary heart disease in men and women from Germany—results from the MONICA Augsburg and the PROCAM cohorts

The prediction of the absolute risk of coronary heart disease (CHD) is commonly based on risk prediction equations that originate from the Framingham Heart Study. However, differences in population risk levels compromise the external validity of these risk functions.Participants aged 35-64 years from the MONICA Augsburg (2861 men and 2925 women) and the PROCAM (5527 men and 3155 women) cohorts were followed-up with regard to incident non-fatal myocardial infarction (MI) and fatal coronary events. For each participant, the predicted absolute risk of fatal plus non-fatal events was derived using Framingham risk equations. Predicted and actually observed risks were compared.The two cohorts were similar in their baseline characteristics. Coronary risk predicted by the Framingham risk function substantially exceeded the risk actually observed in the German cohorts, irrespective of gender. The difference between predicted and observed absolute CHD risk increased with age while the ratio of predicted over observed risk remained constant at about a value of 2. Taking potentials for underascertainment in the German cohorts due to unrecognised MI and sudden deaths into account, the residual magnitude of risk overestimation by the Framingham risk function is probably at least 50%.Local guidelines for the management of patients with risk factors need to correct for this overestimation to avoid inadequate initiation of treatment and inflation of costs in primary prevention. Similar studies should be conducted in other populations with the aim of defining appropriate factors that calibrate absolute risk predictions to local population levels of CHD risk.