Coronary mortality in France according to data sources

Background: Since 1985, two sources of information currently yield coronary disease frequency indicators among the French population: the national cause of death statistics set up by the CepiDC (INSERM), on the one hand, and three registries recording myocardial infarction and coronary deaths as defined by the WHO MONICA Project in three regions (Bas-Rhin, Communaute Urbaine de Lille, Haute-Garonne) on the other hand. Particularly, an inquiry for each possibly coronary death allows the registries to conclude positively (with or without a myocardial infarction), negatively or that no conclusion can be drawn because of insufficient data. The aim of the present work is to analyze concordance between coronary deaths issuing from the two sources according to their definition, while taking into account, or not, multiple causes listed on the death certificates. Material and methods: In total, 4,664 deaths occurring in 2000 in the 35-64 year-old population of the three regions identified by the CepiDc were paired with the 812 deaths analyzed by the registries. The MONICA classification was compared with that of the CepiDC which used the ICD 10th Revision of the initial cause or after taking into account multiple causes. In each case, the concordance between the final classifications (coronary deaths or not) and the mortality ratio obtained from the two sources were computed. Results and conclusions: Eight hundred and six deaths could be paired: 310 with a coronary cause according to the registries, 420 of presumed coronary cause but with insufficient data and 76 of non coronary origin. Whereas the total number of coronary deaths was similar for the two sources, their concordance was relatively low (kappa=0.61). However, when the deaths with insufficient data were included in the MONICA definition, concordance decreased and a large underestimation (59%) of the coronary mortality is given by the national statistics as compared to the registries. Taking into account multiple causes of death and not only the initial cause permitted partly to reduce this underestimation (42%) and to increase concordance (kappa from 0.46 to 0.51). These findings have important consequences for international comparisons concerning coronary disease. Indeed, the MONICA Project showed that the frequency of deaths with insufficient data was especially elevated in France leading to an underestimation of the coronary death rates provided by the national statistics in comparison with other countries, particularly in Europe.