Abstract Body: Introduction: Patients with end-stage chronic kidney disease (CKD) are less physically active than those without CKD. Those who receive hemodialysis (HD) may be less active, especially on HD days, given that most patients are sited for ~3 hours during HD. Nevertheless, limited evidence exists on quantifying activity differences across HD and interdialytic days.

Methods: In a cross-sectional study of patients 18 years and older undergoing HD three times per week in a tertiary hospital in Mexico City without contraindications for physical activity or significant mobility limitations, we measured free-living physical activity using wrist accelerometry. Patients have three interdialytic periods each week and three days. On an HD day, some patients have morning sessions (starting at 7 AM), some mid-day sessions (beginning between 11 AM-12:30 PM), and some have evening sessions (starting between 3:30-4:30 PM).
The patients wore a triaxial accelerometer in their non-dominant wrist (only removing it for water activities longer than 30 minutes) for 7 days. Valid days had ≥90% of wear time. We derived total activity counts (TAC), time spent active (minutes), and the active-to-sedentary transition probability (ASTP, a measure of fragmentation; higher ASTP= more fragmented activity). With linear regressions accounting for correlation of repeated measures, we estimated differences in TAC, active time, and ASTP. We plotted minute-level median activity counts separately for interdialytic days and HD days by session for descriptive purposes.

Results: In a sample of 27 adults (mean age=39.6, SD=12.5, 41% females), the mean TAC was 2.34 million (SD=0.77 million), time spent active 447 minutes (SD=137.12), and ASTP 25% (SD=7). Compared to interdialytic days, during HD days, patients were less active, and their activity was more fragmented (beta coefficient for TAC= -0.7 million [95% CI -0.9, -0.4], for active time=-103 minutes [-148.5, -58.6] and ASTP= 5% [95% CI 3, 7]). In diurnal plots, we also saw that activity began earlier on HD days and was constantly lower across the day relative to interdialytic days (figure)

Conclusion:
Patients undergoing HD were significantly less physically active and had more fragmented activity patterns on HD days compared to interdialytic days. Interventions aimed at increasing physical activity and reducing sedentary behavior on HD days may be beneficial for improving overall health and quality of life in this population.