Association of physical activity and life space with cognitive frailty in patients on hemodialysis: the REPnet-HD...

Cognitive frailty in community-dwelling older adults is associated with decreased physical activity and limited life space. However, the association between cognitive frailty, physical activity, and life space in older patients undergoing hemodialysis (HD) is unknown. Here, we examined the association between cognitive frailty, physical activity, and range of life space mobility.

We enrolled 236 patients undergoing HD aged > 65 years [62% men, age 74 (70-79) years] in a multicenter prospective cohort study (REPnet-HD). Physical frailty was defined based on the revised Japanese version of the Cardiovascular Health Study criteria, and cognitive function was assessed using the Mini-Cog, with a score of < 3 points indicating cognitive impairment. Cognitive frailty was defined as the coexistence of physical frailty and cognitive impairment, whereas robustness was the absence of either. Life space was assessed using the Life Space Assessment (LSA), and physical activity and sedentary behavior time were assessed using the International Physical Activity Questionnaire (IPAQ)-Short Form. Low activity was defined based on the IPAQ results, sedentary was defined as median sedentary behavior time or longer, and low LSA was defined as an LSA < 40 points. Logistic regression analysis was performed using low activity, sedentary behavior, and a low LSA as dependent variables; the four groups based on physical frailty and cognitive impairment as independent variables (reference: robust); and age, sex, body mass index, comorbidities, albumin, and dialysis vintage as covariates.

Physical and cognitive frailties were observed in 36.4% and 6.8% of the patients, respectively. Low activity was significantly associated with physical frailty [odds ratio (OR); 3.67, 95% confidence interval (CI); 1.85-7.26, p < 0.001] and cognitive frailty (OR; 6.23, 95% CI; 1.28-30.45, p = 0.023). Sedentary behavior was significantly associated with cognitive frailty (OR; 4.24, 95% CI; 1.20-14.86, p = 0.024). A low LSA was significantly associated with physical frailty (OR; 3.93, 95% CI; 1.94-7.93, p < 0.001) and cognitive frailty (OR; 7.82, 95% CI; 2.31-26.44, p < 0.001) with a higher OR for cognitive frailty.

Cognitive frailty was associated with a sedentary lifestyle and a limited life space, and also showed a link to reduced physical activity, particularly in comparison to physical frailty alone.