Diabetes, hypertension and mobility among Brazilian older adults: findings from the Brazilian National Household Sample Survey (1998, 2003 and 2008)

Background: The rapid population ageing has been accompanied by a growing number of older adults experiencing chronic conditions, especially diabetes and hypertension, which are conditions associated to the decline in physical functioning. The aim of this study was to investigate changes in the strength of the association between mobility and two chronic conditions (hypertension and diabetes) in a large representative sample of Brazilian older adults over a ten year period. Methods: The data came from the Brazilian National Household Sample Survey (PNAD) of 1998, 2003 and 2008. The sample comprised 28,943 participants aged 60 years and older investigated in 1998, 35,042 in 2003 and 41,269 in 2008, totalling 105,254 older adults. The dependent variable was the physical mobility index (PMI) constructed based on the Item Response Theory (IRT) using five physical mobility indicators. The chronic conditions were self-reported and the confounders included: age, sex, schooling, ethnicity, family income, household composition, other co-morbidities and use of health services. The association between physical mobility (three different groups) and chronic conditions (hypertension and diabetes) was performed using multinomial logistic regression. Results: Over the ten year period the prevalence of hypertension increased from 44 % (1998), 49 % (2003) to 53 % (2008) (p < 0.001). Similar pattern was observed for the prevalence of diabetes: 10 % in 1998, 13 % in 2003 and 16 % in 2008 (p < 0.001). Overall, physical mobility showed a statistical significant association with both chronic diseases studied even after adjusting for potential confounders. The time-disease interaction term was significant (p < 0.05) for the two chronic conditions studied, and the strength of the associations decreased over the first five years, but it was not sustained between 2003 and 2008. Conclusions: Despite the increases observed in the prevalence of the hypertension and diabetes over the ten year period, the decrease in strength of the association with physical mobility during the first period could be explained by improvements in health services and treatment of older adults. Special attention should be given to the treatment and management of diabetes in order to avoid declines in physical mobility levels.