Geographical distribution of ischemic heart disease mortality and its relationship to the climatic conditions in Venezuela

Abstract

The ischemic heart mortality rate was studied in Venezuela in relation to climate. First, a descriptive study showed the distribution of the ischemic heart mortality rate in the country. The standardized mortality ratio was a good index for this purpose. Several factors were considered to determine if they had any relation to the ischemic heart mortality rate. The available data did not permit any valid conclusions except for indicating a relationship with some climatic factors. Second, the standard regression analysis applied to standardized mortality ratio and the climatic index showed that they were related. A similar technique was applied to six selected cities. These results showed a high relationship between the climatic elements and the ischemic mortality rate. However, no one climatic element proved to be important throughout the country, but its importance was relative to each particular city. Thus solar radiation was important in Caracas city; the maximum 24 h precipitation in Ciudad Bolivar; the evaporation in Maturin; wind in Merida and San Fernando and relative humidity in Coro. The regression equation for each city was found to be statistically significant. The correlation technique applied to 14 cities showed that low relative humidity and ischemic heart mortality rate were related with a negative coefficient. This unexpected relationship was attributed to the increase of stress associated with high temperature, high wind speed; the possible effect of dehydration and the hypothetical action of the positive ions in the release of serotonin in the formation of thrombosis described by several authors. The data of all cities were combined in order to increase the amount of data and to consider the whole country, but no significant results were found. The areas of potential high risk of the incidence of ischemic mortality rate were identified. This study showed that the weather and climate play an important role in the incidence of the ischemic heart mortality rate in Venezuela.