Physical activity and its trajectory over time and clinical outcomes in hemodialysis patients.

Abstract

We examined whether physical activity measured at starting point and its trajectory over time were simultaneously associated with vital prognosis. This retrospective cohort study included 295 ambulatory maintenance hemodialysis patients (mean age 63.9years; 54.6% male). We measured physical activity at index date (starting point) and its change over 1year as predictors, and all-cause death and cardiovascular events were assessed as the outcomes. Two groups each of high versus low physical activity at starting point (based on 4000 steps per day) and no decline versus decline (based on a predicted mean slope) were created. Cox proportional-hazards regression and Fine-Gray proportional sub-distribution hazards model were used to examine associations between physical activity and its trajectory and clinical outcomes. Decline in physical activity over 1year was associated with a higher risk of all-cause death and cardiovascular events, irrespective of the physical activity at starting point. Furthermore, both lower physical activity at starting point and decrease in physical activity over time were independently associated with a higher risk of all-cause death and cardiovascular events in models in which each exposure was mutually adjusted. Compared to other groups that worsened in either exposure, the lowest risk for death/cardiovascular events was observed in the high at starting point/no decline over time group. Both physical activity at starting point and its change over time were independently associated with vital prognosis. The assessment of both exposures provides additional prognostic information for the assessment of each exposure.