Seasonal patterns of all-cause and malaria mortality in Rural Burkina Faso 1998 - 2007

Abstract

Background: To plan and develop health interventions targeted lessening mortality, reliable and correct empirical data on cause-specific mortality patterns is essential, but such information is still lacking in the developing world. Health and Demographic Surveillance Systems applying the verbal autopsy method allow to obtain longitudinal cause-specific mortality data of populations in poor countries. Physician Coded Verbal Autopsy (PCVA) is usually used to determine the cause of death, but recently the Interpreting Verbal Autopsy (InterVA) method, a computerized model, was alternatively introduced. Objectives: The aim of this study is to determine the effect of season on all-cause and malaria mortality analyzing data of the period 1998 to 2007 obtained by the Nouna Health and Demographic Surveillance System with app. 80,000 individuals in rural northwestern Burkina Faso and to compare seasonal malaria mortality patterns for the PCVA approach as well as for the InterVA model. Methods: All-cause and cause-specific death rates were calculated overall and by age group. Seasonal mortality patterns were modeled using parametric Poisson regression analysis adjusted for sex, area of residence and year of death. Results: Overall, 7,378 deaths were observed corresponding to an average mortality rate of 11.9 deaths per 1,000. InterVA assigned half as many deaths to malaria as physicians did. Both methods showed young children to be most affected by malaria whereas for adults and older people other causes of death played a major role. Despite few discrepancies, both methods showed comparable significant malaria mortality patterns in children with higher rates during the rainy season whereas for adults and old people the highest death rates occurred during the hot dry season for other causes of death. The effect of season is well explained by a parametric sinusoidal function. Under five mortality declined significantly for other causes of death over the years alongside stagnant malaria mortality.