Sedentary behavior as a discriminator of functional disability among older adults: a cross-sectional study

Objectives: To investigate the association between sedentary behavior and functional disability in instrumental activities of daily living among older adults, and to determine the accuracy and optimal cutoff point of sedentary behavior for the discrimination of functional disability. Methods: This is a population-based, cross-sectional epidemiological survey of 318 older adults (mean age: 74.6 ± 9.7 years old) from Northeastern Brazil. Functional disability in instrumental activities of daily living was assessed using the Lawton scale (presence or absence). Sedentary behavior time was quantified using the International Physical Activity Questionnaire. Results: The prevalence of functional disability was 59.7% (women: 68.5%; men: 48.5%; P = 0.001). The median sedentary behavior time was 4.7 h/day. Each 1 h/day increase in sedentary behavior was associated with a 4% increase in the likelihood of functional disability in women (PR: 1.04; 95% CI: 1.01-1.07). Furthermore, in women, sedentary behavior demonstrated an accuracy of 0.61 (95% CI: 0.53-0.68), a sensitivity of 23%, and a specificity of 100% (optimal cutoff point: 7.5 h/day). Conclusion: Sedentary behavior was positively associated with functional disability in instrumental activities of daily living in women but not in men. Additionally, sedentary behavior showed accuracy in discriminating functional disability in women, with the optimal cutoff point identified at 7.5 h/day.