Respiratory mortality trend in the elderly before and after influenza vaccination campaigns againt, Brazil - 1992 to 2005

by Souza Campagna, Aide de

The study objectives were: to analyze the time series (historical trends and seasonality) in mortality rates due to selected respiratory diseases (pneumonias, influenza, bronchitises and obstruction of the respiratory tract) from people older than 60 years in regions of Brazil from 1992 to 2005, and to compare the time series patterns during the periods before and after the intervention of the vaccination campaigns against influenza. It is a mixed longitudinalecological study using secondary data from Mortality Information System (SIM) and elderly population estimated by sex and age from the Brazilian Geography and Statistical Institute (IBGE). To calculate the mortality rates, deaths were stratified by year, month, sex, age group, region and capitals aggregated by region. Subsequently mortality rates werestandardized by sex and/or age using the direct method (standard population: Brazil - Census 2000). For analysis of the mortality given the implementation of the vaccination campaignsagainst influenza, it was used linear regression adjusted by historical trend and sazonality in the study period. Mortality rates had an increased trend as the study population age increased. Moreover, higher mortality rates were also observed among the male population and among individuals living in the Southern, Southeastern and Midwestern regions. Statisticallysignificant reduction of the mortality rates for all the age groups in the period after the introduction of the vaccination campaigns against influenza was identified, after adjusting formortality rate historical trends and seasonality. The study results confirm the important magnitude of the mortality due to influenza-related respiratory diseases among the elderlypopulation in Brazil and strengthening the debate regarding the benefits of the vaccination. Moreover, this study reinforces the need of other research aiming at advancing in the explanations of these findings