Two-year follow-up study of elderly residents in S Paulo, Brazil: methodology and preliminary results

Introduction Previous cross-sectional studies have shown a high prevalence of chronic disease and disability among the elderly. Given Brazil's rapid a ging process and the obvious consequences of the growing number of old peop le with chronic diseases and associated disabilities for the provision of h ealth services, a need was felt for a study that would overcome the limitat ions of cross-sectional data and shed some light on the main factors determ ining whether a person will live longer and free of disabling diseases, the so-called successful aging. The methodology of the first follow-up study o f elderly residents in Brazil is presented. Method The profile of the initial cohort is compared with previous cross-se ctional data and an in-depth analysis of nonresponse is carried out in orde r to assess the validity of future longitudinal analysis. The EPIDOSO ('Epi demiologia do Idoso') Study conducted a two-year follow-up of 1,667 elderly people (65+), living in S. Paulo. The study consisted of two waves, each c onsisting of household, clinical, and biochemical surveys. Results and Conclusions In general, the initial cohort showed a similar pro file to previous cross-sectional samples in S. Paulo. There was a majority of women, mostly widows, living in multigenerational households, and a high prevalence of chronic illnesses, psychiatric disturbances, and physical di sabilities. Despite all the difficulties inherent in follow-up studies, the re was a fairly low rate of nonresponse to the household survey after two y ears, which did not actually affect the representation of the cohort at the final household assessment, making unbiased longitudinal analysis possible . Concerning the clinical and blood sampling surveys, the respondents tende d to be younger and less disabled than the nonrespondents, limiting the use of the clinical and laboratory data to longitudinal analysis aimed at a he althier cohort. It is worth mentioning that gender, education, family suppo rt, and socioeconomic status were not important determinants of nonresponse , as is often the case.