Tendência da mortalidade por doenças respiratórias relacionadas à influenza em idosos de Minas Gerais, 1980 A 2010

Abstract

Aging produces physiological and functional changes which may decrease functional capacity and increase vulnerability of the elderly regarding respiratory disease. In Minas Gerais, these are the second cause of hospitalization and the third cause of death among the elderly. Among these illnesses are those related to influenza, for which the main strategy to reduce its impact is annual vaccination, as provided in the 1999 Brazilian Vaccination Schedule. The aim of this study is to analyse the mortality trends due to influenza-related respiratory diseases in the elderly in the state of Minas Gerais, from 1980 to 2010, and compare the behavior of these time series before and after the inclusion of the influenza vaccine in the vaccination schedule. This is an ecological time series study based on data for mortality due to influenza-related respiratory diseases for subjects over 60 years old living in the state of Minas Gerais. The indicators we used are cause-specific mortality rate, age group (60-69, 70-79, and ≥ 80 years old), sex, and residential macro-region. In order to compare health, sex, and study period macro-regions, mortality rates due to the selected causes were adjusted by age group according to the direct method standardization technique (standard population: Minas Gerais, 2010). Mortality analysis was done by describing rates along time and also by comparing trends through linear regression models. Models were adjusted by percent deaths due to poorly defined cause and also by vaccination coverage after introduction of the campaign. The significance level we used was of 5%. We used data from the Mortality Information System, the National Immunization Program Information System, and the Brazilian Institute of Geography and Statistics. The mortality trends due to influenza-related diseases in the elderly in the state of Minas Gerais suggest a positive impact of the vaccination intervention against influenza in decreasing mortality. Higher rates were seen among men and the elderly at a more advanced age, regardless of sex, for Minas Gerais and its macro-regions. According to the analysis, mortality rate trends increased throughout the period. By comparing the periods before and after the inclusion of vaccination in Minas Gerais and its macro-regions, a significantly increasing trend was seen in the rates before the implementation of the program, and an inversion and stabilization of the trends after implementation, except the Northern macro-region where trends remained constant. Regional variations were seen for mortality rates, SIM data quality and vaccination coverage among the macro-regions included in the study. Changes in mortality rate due to influenza-related respiratory diseases after vaccination campaigns suggest a protective effect for mortality in the elderly in the state of Minas Gerais and raise a debate about the immunization of this population and policy enhancement by considering regional differences.