Associations between levels of physical activity and mortality in older adults: a prospective cohort study

Background- Research using objectively measured physical activity (PA) in older adults to assess relationship between PA levels and mortality is scarce. Objective- To investigate associations between level of physical activity and mortality in older adults over a 4-year period. Methods- The population-based cohort study was carried out including 554 older participants (mean age: 76.2 ± 8.05 years) using data from the SABE study (Health, well-being and aging). Levels of physical activity were measured using accelerometers and participants were divided into tertiles and then categorized into two groups: (I) low level of physical activity and (II) intermediate/high level of physical activity. The dependent variable was mortality between 2010 and 2014. Control variables included socio-demographic and clinical factors. Multiple regression analysis was used from a hierarchical model, grouping the variables into two blocks ordered according to the magnitude of their effect. Results- Our results showed that mortality rate in participants with low level of physical activity was 20/1000 person/year and for those with intermediate/high levels of physical activity was 14/1000 person/year. In the adjusted model, by sociodemographic and clinical variables, those with low levels of physical activity presented a higher risk for mortality (OR = 2.79, 95%CI = 1.71–4.57) when compared to individuals with intermediate/high levels of physical activity. Conclusion- Older adults with low levels of physical activity have a higher chance of mortality as compared to those with intermediate/high levels of physical activity, regardless of sociodemographic and clinical variables.