Seasonal Variation in mortality for five main death causes. Cuba, 1996-2006

Background and purpose: Mortality's seasonal variation has long been described all over the world for many death causes. Periodic changes in the weather conditions of temperate countries have been well recognised as risk factors for seasonal mortality but there is no sufficient evidence of this in tropical countries where seasons are not so well defined and there are no great differences in temperature. There are no recent studies about this matter in Cuba. The aim of this paper is to describe the seasonality of 5 different death causes (heart diseases, cerebrovascular diseases, accidents, suicides and homicides) based on monthly data collected during the period 1996-2006 using a simple and replicable method for undeveloped countries. Methods: The presence of seasonal variation in several causes of death was explored with box and whiskers plots. Monthly total numbers of deaths were adjusted to a standard 30 days month in all time series. Death causes were selected acording to their relevance and data obtained from National Bureau of Statistics of the Cuban Ministry of Health for the period January 1996December 2006. Results: A total of 868 982 deaths occurred during the 11 year period of the study in Cuba: heart diseases (232 829), cerebrovascular diseases (89 263), accidents (53 341), suicides (19 007) and homicides (7 316). Monthly deaths due to heart diseases showed high median values in January, February and December. Deaths by cerebrovascular diseases showed their highest median values during the months of January, February, March and December. The median number of monthly deaths by accidents was highest during July and August. Deaths due to suicides were higher in Jun, May and July. Seasonality of monthly deaths by homicides was not so evident. Conclusions: Seasonal variation of mortality for several death causes was highlighted using a simple, easy and replicable method to quickly ascertain the presence of seasonality of death causes which can be very atractive for undeveloped countries. The work was done at: The National Unit of Trend Analysis. Cuban Ministry of Health.