Longitudinal cross-national analysis of coronary mortality.

In this study an attempt was made to investigate the application of epidemiological methodology in a cross-national context of studying the variation of coronary mortality. The data on the exposing factors of coronary mortality, the consumption of cigarettes and dairy products, were obtained from OECD statistics, and the data concerning the mortality of coronary heart disease were obtained from World Health Organization statistics. From the correlation and regression analyses performed on the basis of data from 14 countries it appeared that the cross-sectional exposure measurements strongly correlate over decades. For the consumption of cigarettes the time-lag found was from one to two years, while for the consumption of dairy products the respective time-lag was about six to eight years with respect to the effects on the coronary mortality. Because of the small number of observations available the statistical results should not be examined in terms of precise estimates of magnitude but rather in terms of the existence and the direction of relationship between the changes in coronary mortality and the consumption of cigarettes and dairy products. Although the data were insufficient to examine the confounding between the grouping of observations, and length of exposure, they did provide enough information to illustrate the importance of these two methodological aspects in analyses of populations.