Association of Cognitive Frailty with Physical Activity and Life-space in Patients on Hemodialysis: The REPnet- HD Study

Background 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 patient undergoing hemodialysis (HD) is unknown. Here, we examined the association between cognitive frailty, physical activity and range of life-space mobility. Methods 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 robust 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, and 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. Results 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 was significantly associated with cognitive frailty (OR; 4.24, 95% CI; 1.20–14.86, p = 0.024). 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. Conclusion Cognitive frailty may be associated with a higher risk of low activity due to a sedentary lifestyle and limited life space than physical frailty.