Chronic kidney disease (CKD) is highly prevalent in the United States and throughout the world,(1) with approximately 13% of adults affected.(2) In addition, according to recent estimates, almost half of patients with CKD stages 3 to 5 are 70 years of age and older.(2) In the United States, the number of prevalent end-stage renal disease cases continues to increase in patients older than age 65. In light of the demographic characteristics of patients with CKD and ESRD, there has been considerable focus on associations between CKD and cardiovascular outcomes.(3) Until recently, less attention had been paid to other consequences of CKD in general and among older individuals with CKD in particular, but there is now solid evidence linking CKD with impairments of physical function, cognitive function, and emotional function and quality of life. This review summarizes available literature on these topics, focusing specifically on physical functioning and frailty, cognitive function, emotional health, including depression and anxiety, and health-related quality of life.

Objective(s)

The newly developed Low Physical Activity Questionnaire (LoPAQ) was designed to capture the low activity level among typically sedentary patients undergoing dialysis and correlated well with a physical activity questionnaire used in the general population. However, this instrument has not been validated against a more objective measure.

Methods

We recruited patients receiving dialysis for ≥3 months from 3 dialysis facilities in San Francisco. Spontaneous walking activity was measured by pedometers over 7 days including a weekend and used as the standard reference. Patients were instructed to record their activities and step count readings. Study coordinators administered the LoPAQ during a dialysis session (hemodialysis [HD]) or clinic visit (peritoneal dialysis [PD]). The LoPAQ ascertains time and energy expended in walking activity, as well as light, moderate, and vigorous activity, and total physical activity during a 1-week recall period with 11 simple questions and requires approximately 10 minutes to administer. The LoPAQ also asks about time spent in sitting activities over 1 week. Spearman correlation was used to determine whether the LoPAQ results correlate with step counts.

Results

Sixty dialysis patients (HD = 48, PD = 12) completed the LoPAQ and wore a pedometer for 1 week. Mean age was 58.0 ± 12.7 years, 78.3% were men, and median dialysis vintage was 3.1 (IQR, 1.1-5.8) years. Median step count was 2,630.5 (1,270.7-5,137) steps/day. Most patients (82.8%) reported walking activity around the neighborhood, for transportation, and/or for fitness or pleasure, with a median of 595 (70-1,566.3) kcal/week. Total kilocalories per week of physical activity reported on the LoPAQ were 655 (422.8-2,336.8). Participants reported an average of 5 (3-8) sedentary hours per day. Energy expenditure in walking by the LoPAQ was highly correlated with weekly step counts (rho = 0.53, P < .001). In addition, the overall activity reported on the LoPAQ correlated with weekly pedometer readings (rho = 0.35, P = .01) and did not differ between HD and PD patients.

Conclusions

The LoPAQ was easier and less time-consuming than previously validated physical activity questionnaires. LoPAQ demonstrated a good correlation with objective pedometer step counts among dialysis patients, similar to other physical activity instruments used in healthier and more active populations.

Introduction

Patients on hemodialysis experience a heavy burden of symptoms that may be related to the low levels of physical activity reported in this population. We hypothesized that physical activity would be inversely related to symptom severity and that depression might mediate this association.

Methods

We designed a cross-sectional study of 48 patients receiving hemodialysis at 3 San Francisco dialysis clinics. Physical activity was measured using pedometers and recorded within 1 week of symptom assessment. Symptoms were assessed using total symptom burden and severity on the Dialysis Symptom Index (DSI; burden 0-29, severity 0-145), individual symptoms on the DSI (0-5), Kidney Disease Quality of Life Vitality scores, (0-100), and the Center for Epidemiologic Study-Depression (0-60).

Results

Median daily step count was 2631 (25th, 75th percentile 1125, 5278). Seventy-three percent of patients reported fatigue. After adjustment for age, sex, diabetes, and serum albumin, physical activity was associated with 0.2 points lower fatigue severity per 1000 steps per day (95% confidence interval [CI] -0.3 to 0.0), P = 0.04. Physical activity was also associated with higher Vitality score (2.36 points per 1000 steps; 95% CI 0.07-4.65) and lower insomnia scores (-0.1 points per 1000 steps; 95% CI -0.3 to 0.0], P < 0.05) in our adjusted models. Physical activity was not associated with other symptoms.

Conclusion

Because the study was cross-sectional, we cannot determine whether physical activity lowers fatigue and insomnia or whether less insomnia and fatigue increase physical activity. However, interventions to increase physical activity should be considered alongside current strategies as a possible approach to managing fatigue and insomnia.

Background

A randomized trial of a pedometer-based intervention with weekly activity goals led to a modest increase in step count among dialysis patients. In a secondary analysis, we investigated the effect of this intervention on body composition.

Methods

Sixty dialysis patients were randomized to standard care or a 6-month program consisting of 3 months of pedometers and weekly step count targets and 3 months of post-intervention follow-up. We obtained bioelectrical impedance spectroscopy (BIS) data on 54 of these patients (28 control, 26 intervention) and used linear mixed-modeling (adjusted for sex and dialysis modality) to estimate differences in change in total-body muscle mass (TBMM) adjusted for height², fat mass (kg), and body mass index (BMI) (kg/m²) between control and intervention groups.

Results

The median age of participants was 57.5 years (53-66), and 76% were men. At baseline, there was no significant difference between groups in age, BMI, race, or body composition, but there were more men in the intervention group. After 3 months, patients in the intervention group increased their average daily steps by 2414 (95% CI 1047, 3782) more than controls (p < 0.001), but there were no significant differences in body composition. However, at 6 months, participants in the intervention had a significantly greater increase from baseline in TBMM of 0.7 kg/m² (95% CI 0.3, 1.13), decrease in fat mass (- 4.3 kg [95% CI -7.1, - 1.5]) and decrease in BMI (- 1.0 kg/m² [95% CI -1.8, - 0.2]) relative to controls. In post-hoc analysis, each increase of 1000 steps from 0 to 3 months was associated with a 0.3 kg decrease in fat mass (95% CI 0.05, 0.5) from 0 to 6 months, but there was no dose-response relationship with TBMM/ht² or BMI.

Conclusion

A pedometer-based intervention resulted in greater decreases in fat mass with relative preservation of muscle mass, leading to a greater decrease in BMI over time compared with patients not in the intervention. These differences were driven as much by worsening in the control group as by improvement in the intervention group. Step counts had a dose-response relationship with decrease in fat mass.

Trial registration

ClinicalTrials.gov (NCT02623348). 02 December 2015.

Rationale & objective

Patients receiving dialysis report very low physical activity. We implemented a pilot trial to assess the feasibility of a pedometer-based intervention to gather preliminary evidence about its impact on physical activity, symptoms, and surrogates of cardiovascular risk.

Study design

Pilot randomized controlled trial.

Setting & participants

60 dialysis patients from San Francisco dialysis clinics.

Intervention

Participants were randomly assigned 1:1 to receiving pedometers with weekly step goals or usual care for 3 months.

Outcomes

The primary outcome was step counts, measured using pedometers. Secondary outcomes included physical performance using the Short Physical Performance Battery, the Physical Function and Vitality scales of the 36-Item Short Form Health Survey, the Dialysis Symptoms Index, and the Center for Epidemiologic Studies-Depression Scale, with endothelial function as a secondary and heart rate variability as an exploratory surrogate measure of cardiovascular risk. Targeted enrollment was 50% and targeted completion was 85%.

Results

49% of approached patients were enrolled, and 92% completed the study. After 3 months, patients randomly assigned to the intervention (n=30) increased their average daily steps by 2,256 (95% CI, 978-3,537) more than the 30 controls (P<0.001). Heart rate variability (standard deviation of N-N intervals) increased by 14.94 (95% CI, 0.31-33.56) millisecondsin the intervention group as compared with controls (P = 0.05). There were no statistically significant differences across intervention groups in symptoms, physical performance, or endothelial function. Participants in the intervention group reverted to baseline steps during the postintervention follow-up.

Limitations

The Northern California study setting may limit generalizability. Walking does not capture the full spectrum of physical activity.

Conclusions

A short-term pedometer-based intervention led to increased step counts in dialysis patients, but the increase was not sustained. Pedometer-based interventions are feasible for dialysis patients, but future studies are needed to address whether more prolonged interventions can improve physical function or symptoms.

Funding

Supported by grants from the American Kidney Fund, National Institutes of Health-National Institute of Diabetes and Digestive and Kidney Diseases, and International Society of Nephrology.

Trial registration

Registered at ClinicalTrials.gov with study identifier NCT02623348.

The relative importance of sarcopenia and its individual components as independent predictors of mortality in the dialysis population has not been determined. We estimated whole-body muscle mass using pre-dialysis bioimpedance spectroscopy measurements in 645 ACTIVE/ADIPOSE-enrolled prevalent hemodialysis patients from San Francisco and Atlanta. Low muscle mass was defined as two standard deviations below sex-specific means for young adults from NHANES and indexed to height², body weight, body surface area, or body mass index. We evaluated the association of sarcopenia (low muscle mass) by four indexing methods, weak hand grip strength, and slow gait speed with mortality. Seventy-eight deaths were observed during a mean follow-up of 1.9 years. Sarcopenia was not significantly associated with mortality after adjusting for covariates. No muscle mass criteria were associated with death, regardless of indexing metrics. In contrast, having weak grip strength or slow walking speed was associated with mortality in the adjusted model. Only gait slowness significantly improved the predictive accuracy for death with an increase in C-statistic from 0.63 to 0.68. However, both gait slowness and hand grip weakness significantly improved the net reclassification index compared to models without performance measures (50.5% for slowness and 33.7% for weakness), whereas models with muscle size did not. Neither sarcopenia nor low muscle mass by itself was a better predictor of mortality than functional limitation alone in patients receiving hemodialysis. Thus, physical performance measures, including slow gait speed and weak hand grip strength, were associated with mortality even after adjustment for muscle size and other confounders.

Background

A randomized trial of a pedometer-based intervention with weekly activity goals led to increased walking among dialysis patients. However, the association of participant-expressed motivations and barriers to participation and performance in such an intervention has not been determined.

Methods

Thirty dialysis patients were randomized to a 12-week pedometer-based intervention with weekly step goals. Participants were asked about motivations and barriers to the increasing activity via weekly semi-scripted telephone interviews. We examined the association of these motivations and barriers with achieving weekly goals, reaching overall targets and increasing steps through multivariable linear and logistic regression analyses adjusted for age, sex, body mass index, dialysis modality and baseline steps.

Results

The most common motivations were desire to maintain/improve functional ability (30%) and activity (30%). The most common barriers were health-related (33%). Motivation to maintain/improve functional ability was associated with achieving weekly goals 17.9% more often [95% confidence interval (CI) 1.7-34.2] and with a greater increase in steps (1524 steps; 95% CI 61-2989) than those lacking this motivation. Experiencing a health-related barrier was not associated with the decreased achievement of weekly goals but was associated with lower odds of reaching overall targets (odds ratio = 0.06; 95% CI 0.01-0.53) and a smaller increase in steps (-1640 steps, 95% CI -3244 to -36). No patients who reported weather/environmental barriers or safety concerns reached overall targets.

Conclusions

Participants who express a desire to maintain/improve functional ability may be particularly suited for activity interventions. Health-related setbacks should be met with revised goals. Reporting environmental or safety concerns may merit lowering overall targets.