Institut of Social Medicine, Epidemiology and Health Economics, Charite Hospital, Berlin, Germany
* Correspondence to: Tel: +49 30 450 529026; Fax: +49 30 450 529902
E-mail address: jacqueline.mueller-nordhorn{at}charite.de
Received 24 June 2003; accepted 29 July 2003
In the May 2003 issue, Hense et al.1compared the predicted risk of coronary heart disease to the observed risk in participants of two distinct German cohorts-the PROCAM and the MONICA Augsburg studies-using the Framingham risk equation. The authors conclude that the Framingham risk function overestimates the actual coronary risk in the German population by at least 50% and suggest that national guidelines should correct for this overestimation. We do not agree with such consequence for the following reasons. Firstly, the PROCAM study is an occupational cohort and, therefore, included a selected workforce sample whereas the Framingham study recruited participants from households.2Participants who are working have been found to be healthier than the general population-a phenomenon known as the healthy worker effect.3,4The study by Froom et al. indicated that occupationally active persons have a standardized mortality ratio for cardiovascular mortality of about 75% compared to the general population.4Secondly, there is a marked regional variation in cardiovascular mortality within Germany.5Augsburg is situated in the southern state of Bavaria, which belongs to the states with lower coronary heart disease mortality inGermany whereas age-adjusted coronary mortality of other states (e.g. in the North-East) is up to twofold higher. Therefore, the observed risk of coronary heart disease in the MONICA cohort should not be considered representative for the general German population. Thirdly, Hense et al. feel that the ratio of predicted over observed risk remains rather constant over different age groups but this statement is not supported by the data. For example, the ratio decreases from 5.7 (3544 years of age) to 2.4 (5564 years of age) for women in the MONICA study and from 2.5 to 1.6 for the respective male groups in the PROCAM study. The Framingham risk equation was developed for participants aged 3074 years6and has already been reported to overestimate the risk of coronary heart disease in younger participants.7Due to the age restrictions in the PROCAM and MONICA cohorts, the observed risk is not available for older age groups that may well be associated with a considerably lower gap between predicted and observed risk. Finally, the authors recommend the use of the PROCAM scoring scheme for predicting the risk of coronary heart disease in the German setting.8However, this novel scoring scheme was validated only for male participants aged 3565 years and should not be applied to women and to older patients in general clinical practice. We conclude that the interesting analyses by Hense et al. do not justify the modification of current guidelines. However, secular trends and/or regional variation in coronary heart disease certainly warrant further research into the adequate adjustment of currently used risk functions. Furthermore, future population strategies may complement or even replace targeting high-risk individuals in the prevention of coronary heart disease as proposedrecently.9
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