Objectives: The phenotype associated to reduced physical activity (PA) in dialysis patients is poorly documented. We here evaluate weekly PA in two independent cohorts.
Methods: Cross-sectional study with PA assessed by the number of steps/day measured by pedometer in two cohorts of prevalent dialysis patients: (1) peritoneal dialysis (PD) patients (n = 64; 62 ± 14 years; 70 % men) from Stockholm, Sweden using the pedometer for 7 consecutive days; (2) hemodialysis (HD) patients (n = 78; 63 ± 12 years; 65% men) from a single center in Madrid, Spain using the pedometer for 6 consecutive days: 2 HD days, 2 non-HD midweek days and 2 non-HD weekend days. In both cohorts, comorbidities, body composition, nutritional status, and related biomarkers were assessed. Cohorts were not merged; instead data were analyzed separately serving as reciprocal replication analyses.
Results: Most patients (63% of PD and 71% of HD) were considered sedentary (<5,000 steps/day). PD patients had on average 4,839 ± 3,313 steps/day. HD patients had 3,767 ± 3,370 steps/day on HD-free days, but fewer steps/day on HD days (2,274 ± 2,048 steps/day; p < 0.0001). In both cohorts, and across increasing PA tertiles, patients were younger and had less comorbidities. Higher PA was also accompanied by better nutritional status (depicted by albumin, pre-albumin, creatinine and normalized protein catabolic rate in HD, and by albumin and subjective global assessment [SGA] in PD), higher lean body mass, and lower fat body mass (bioimpedance and/or dual-energy X-ray absorptiometry [DEXA]). Higher levels of PA were accompanied by lower levels of C-reactive protein in PD. Age and lean body mass were the strongest multivariate predictors of PA in both cohorts.
Conclusion: There is a high prevalence of sedentary behavior in dialysis patients. Better physical activity was consistently associated with younger age, lower presence of comorbidities and better nutritional status. Pedometers represent a simple and inexpensive tool to objectively evaluate physical activity in this patient population.