Drop in cardiovascular and coronary mortality in Lombardia, 1969-1987. Evaluation of reliability of the estimates and possible explaining hypothesis]

The results of the present analysis indicate, from 1969 to 1987, a sharp and stable decline in cardiovascular (CVD) mortality in Italians aged 35-74 years (37.6% in males 53.6% in females). These trends were responsible for consistent reductions of total mortality (27.5% and 38% in the two gender groups, respectively), and for the increase of life expectancy. The decrease involved the two major components of CVD mortality, i.e. coronary heart disease (CHD) (23% in males and 44% in females) and cerebrovascular diseases (Stroke) (42.6% in the former and 51% in latter gender group). All these mortality decrements have been higher in the Lombardia Region. Comparing age-adjusted mortality rates in 1968 and 1987, it was possible to estimate that 23,040 deaths were saved in one year among the residents of this northern part of Italy, and the decrease of CHD mortality was responsible for about 30% of the total national decrement of CHD deaths, within comparable age strata. This is attributable both to the higher rates registered at the beginning of the studied period, and to the sharper decline observed. The social impact, in terms of reduction of deaths, was prominent for males. Among the northern male population, the amount of prevented deaths due to CHD and Stroke was equivalent (2072 vs 2172). Data from a MONICA Collaborating Center, located in the region--Area Brianza--, allow us to estimate, for coronary diagnoses reported on death certificates in the 1980s, acceptable levels of accuracy (Cohen's Kappa of .35, with 99% CI .27-.43) and sensitivity (87%). In comparison with earlier estimates carried out in the late 1970s, it is possible to hypothesize an increase of sensitivity over time for certified myocardial infarction diagnoses, which could have contributed to the underestimation of the observed decrements. In dealing with estimates of the reasons for these declines, only suggestions could be addressed because results of specific and comprehensive studies are not presently available. By comparing MONICA data with the results obtained in earlier surveys, it is possible to estimate that about 20 to 30% of the CHD decline, which occurred in the Region, might be attributed to the decrease of in-hospital coronary case-fatality. Moreover, major coronary risk factors (total cholesterol, blood pressure and cigarette smoking) show parallel positive changes, but their contribution in predicting the CHD downfall is difficult to evaluate on the basis of existing data.(ABSTRACT TRUNCATED AT 400 WORDS)