Physical Function and Physical Activity in Peritoneal Dialysis Patients.

BACKGROUND: Physical functioning (PF) and physical activity (PA) are low in patients treated with maintenance hemodialysis (MHD). Little information exists on this topic in patients treated with peritoneal dialysis (PD). The objective of this study was to compare PF and PA in patients with Stage-5 chronic kidney disease (CKD) treated with PD and in-center MHD. METHODS: Physical functioning was measured in 45 prevalent PD patients using standard physical performance measures that include gait speed, chair stand, standing balance, 6-minute-walk, incremental shuttle walk and self-reported PF using the short form (SF)-36 questionnaire. Physical activity was determined from self-report and using the Community Healthy Activities Model Program for Seniors (CHAMPS) questionnaire. Scores for the short physical performance battery (SPPB) were calculated. In-center MHD patients were matched by age, gender, and diabetes status to the PD patients. RESULTS: Unadjusted comparisons showed significantly higher 6-minute-walk distance, shuttle-walk distance and hand-grip in the PD patients. Adjustment in multiple regression analysis resulted in only gait speed being significantly different between the groups. All test results in both groups were lower than reference values for age and gender in the general population, and were at the levels indicating impairment. Physical activity was not different between the 2 groups (average age 49 yrs), and both groups had weekly caloric expenditure from all exercise and from moderate-intensity exercise that was similar to older (> 70 yrs) community-dwelling adults. Adjusted association indicated that PA was significantly associated with shuttle-walk distance. CONCLUSIONS: Physical functioning and PA measures were low in both PD and MHD groups. Interventions to improve PA and PF should be strongly considered for both PD and MHD patients.

Gait Speed and Mortality, Hospitalization, and Functional Status Change Among Hemodialysis Patients: A US Renal Data System Special Study.

BACKGROUND: Slow walk (gait) speed predicts functional decline, institutionalization, and mortality risks in the geriatric population. A gait speed evidence base for dialysis patient outcomes is needed. STUDY DESIGN: Prospective cohort study. SETTING & PARTICIPANTS: 752 prevalent hemodialysis (HD) patients aged 20 to 92 years evaluated in 2009 to 2012 in 7 Atlanta and 7 San Francisco clinics in a US Renal Data System special study. PREDICTOR: Usual walk speed in meters per second, categorized as ≥0.6 m/s (baseline n=575), <0.6 m/s (baseline n=94), and unable to perform walk test (baseline n=83). OUTCOMES: Survival; hospitalization; activities of daily living (ADL) difficulty; 36-Item Short Form Health Survey (SF-36) Physical Function score. MEASUREMENTS: Cox proportional hazards models investigated gait speed and mortality over a median follow-up of 703 days. Multivariable logistic or linear regression models estimated associations of baseline gait speed with hospitalization, need for ADL assistance, and SF-36 Physical Function score after 12 months. RESULTS: Participants who walked ≥0.6 m/s had 53 (9%) deaths, those who walked <0.6 m/s had 19 (20%) deaths, and those unable to walk had 37 (44%) deaths. Adjusted mortality hazard ratios were 2.17 (95% CI, 1.19-3.98) for participants who walked <0.6 m/s and 6.93 (95% CI, 4.01-11.96) for those unable to walk, compared with participants walking ≥0.6 m/s. After 12 months, compared with baseline walk speed ≥ 1.0 m/s (n=169 participants), baseline walk speed of 0.6 to <0.8 m/s (n=116) was associated with increased odds of hospitalization (OR, 2.04; 95% CI, 1.19-3.49) and ADL difficulty (OR, 3.88; 95% CI, 1.46-10.33) and a -8.20 (95% CI, -13.57 to -2.82) estimated change in SF-36 Physical Function score. LIMITATIONS: Cohort not highly representative of overall US in-center HD population. CONCLUSIONS: Because walking challenges the heart, lungs, and circulatory, nervous, and musculoskeletal systems, gait speed provides an informative marker of health status. The association of gait speed with HD patients' risk for functional decline warrants continued study.

Low Physical Function in Maintenance Hemodialysis Patients Is Independent of Muscle Mass and Comorbidity.

OBJECTIVES: It is unknown whether muscle wasting accounts for impaired physical function in adults on maintenance hemodialysis (MHD). DESIGN: Observational study. SETTING: Outpatient dialysis units and a fall clinic. SUBJECTS: One hundred eight MHD and 122 elderly nonhemodialysis (non-HD) participants. EXPOSURE VARIABLE: Mid-thigh muscle area was measured by magnetic resonance imaging. MAIN OUTCOME MEASURE: Physical function was measured by distance walked in 6 minutes. RESULTS: Compared with non-HD elderly participants, MHD participants were younger (49.2 ± 15.8 vs. 75.3 ± 7.1 years; P < .001) and had higher mid-thigh muscle area (106.2 ± 26.8 vs. 96.1 ± 21.1 cm2; P = .002). However, the distance walked in 6 minutes was lower in MHD participants (322.9 ± 110.4 vs. 409.0 ± 128.3 m; P < .001). In multiple regression analysis adjusted for demographics, comorbid conditions, and mid-thigh muscle area, MHD patients walked significantly less distance (-117 m; 95% confidence interval: -177 to -56 m; P < .001) than the non-HD elderly. CONCLUSIONS: Even when compared with elderly non-HD participants, younger MHD participants have poorer physical function that was not explained by muscle mass or comorbid conditions. We speculate that the uremic milieu may impair muscle function independent of muscle mass. The mechanism of impaired muscle function in uremia needs to be established in future studies.

The BASES expert statement on exercise therapy for people with chronic kidney disease.

Chronic kidney disease (CKD) is becoming a serious health problem throughout the world and is one of the most potent known risk factors for cardiovascular disease, which is the leading cause of morbidity and mortality in this patient population. Physical inactivity has emerged as a significant and independent risk factor for accelerated deterioration of kidney function, physical function, cardiovascular function and quality of life in people in all stages of CKD. CKD specific research evidence, combined with the strong evidence on the multiple health benefits of regular and adequate amounts of PA in other cardiometabolic conditions, has resulted in physical inactivity being identified by national and international CKD clinical practice guidelines as one of the multiple risk factors that require simultaneous and early intervention for optimum prevention/management of CKD. Despite this realisation, physical inactivity is not systematically addressed by renal care teams. The purpose of this expert statement is therefore to inform exercise and renal care specialists about the clinical value of exercise therapy in CKD, as well as to provide some practical recommendations on how to more effectively translate the existing evidence into effective clinical practice.

Characterization of physical activity and sitting time among patients on hemodialysis using a new physical activity instrument.

OBJECTIVES: Physical activity questionnaires usually focus on moderate to vigorous activities and may not accurately capture physical activity or variation in levels of activity among extremely inactive groups like dialysis patients. DESIGN: Cross-sectional study. SETTING: Three dialysis facilities in the San Francisco Bay Area. SUBJECTS: Sixty-eight prevalent hemodialysis patients. INTERVENTION: We administered a new physical activity questionnaire designed to capture activity in the lower end of the range, the Low Physical Activity Questionnaire (LoPAQ). MAIN OUTCOME MEASURE: Outcome measures were correlation with a validated physical activity questionnaire, the Minnesota Leisure Time Activity (LTA) questionnaire and with self-reported physical function (physical function score of the SF-36) and physical performance (gait speed, chair stand, balance, and short physical performance battery). We also determined whether patients who were frail or reported limitations in activities of daily living were less active on the LoPAQ. RESULTS: Sixty-eight participants (mean age 59 ± 14 years, 59% men) completed the study. Patients were inactive according to the LoPAQ, with a median (interquartile range) of 517 (204-1190) kcal/week of physical activity. Although activity from the LTA was lower than on the LoPAQ (411 [61-902] kcal/week), the difference was not statistically significant (P = .20), and results from the 2 instruments were strongly correlated (rho = 0.62, P < .001). In addition, higher physical activity measured by the LoPAQ was correlated with better self-reported functioning (rho = 0.64, P < .001), better performance on gait speed (rho = 0.32, P = .02), balance (rho = 0.45, P < .001), and chair rising (rho = -0.32, P = .03) tests and with higher short physical performance battery total score (rho = 0.51, P < .001). Frail patients and patients with activities of daily living limitations were less active than those who were not frail or limited. CONCLUSIONS: The LoPAQ performed similarly to the Minnesota LTA questionnaire in our cohort despite being shorter and easier to administer.

Association of physical function with predialysis blood pressure in patients on hemodialysis.

BACKGROUND: New information from various clinical settings suggests that tight blood pressure control may not reduce mortality and may be associated with more side effects. METHODS: We performed cross-sectional multivariable ordered logistic regression to examine the association between predialysis blood pressure and the short physical performance battery (SPPB) in a cohort of 749 prevalent hemodialysis patients in the San Francisco and Atlanta areas recruited from July 2009 to August 2011 to study the relationship between systolic blood pressure and objective measures of physical function. Mean blood pressure for three hemodialysis sessions was analyzed in the following categories: <110 mmHg, 110-129 mmHg (reference), 130-159 mmHg, and ≥160 mmHg. SPPB includes three components: timed repeated chair stands, timed 15-ft walk, and balance tests. SPPB was categorized into ordinal groups (≤6, 7-9, 10-12) based on prior literature. RESULTS: Patients with blood pressure 130-159 mmHg had lower odds (OR 0.57, 95% CI 0.35-0.93) of scoring in a lower SPPB category than those whose blood pressure was between 110 and 129 mmHg, while those with blood pressure≥160 mmHg had 0.56 times odds (95% CI 0.33-0.94) of scoring in a lower category when compared with blood pressure 110-129 mmHg. When individual components were examined, blood pressure was significantly associated with chair stand (130-159 mmHg: OR 0.59, 95% CI 0.38-0.92) and gait speed (≥160 mmHg: OR 0.59, 95% CI 0.35-0.98). Blood pressure≥160 mmHg was not associated with substantially higher SPPB score compared with 130-159 mmHg. CONCLUSIONS: Patients with systolic blood pressure at or above 130 mmHg had better physical performance than patients with lower blood pressure in the normotensive range. The risk-benefit tradeoff of aggressive blood pressure control, particularly in low-functioning patients, should be reexamined.

Associations of self-reported physical activity types and levels with quality of life, depression symptoms, and mortality in hemodialysis patients: the DOPPS.

BACKGROUND AND OBJECTIVES: Physical activity has been associated with better health status in diverse populations, but the association in patients on maintenance hemodialysis is less established. Patient-reported physical activities and associations with mortality, health-related quality of life, and depression symptoms in patients on maintenance hemodialysis in 12 countries were examined. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: In total, 5763 patients enrolled in phase 4 of the Dialysis Outcomes and Practice Patterns Study (2009-2011) were classified into five aerobic physical activity categories (never/rarely active to very active) and by muscle strength/flexibility activity using the Rapid Assessment of Physical Activity questionnaire. The Kidney Disease Quality of Life scale was used for health-related quality of life. The Center for Epidemiologic Studies Depression scale was used for depression symptoms. Linear regression was used for associations of physical activity with health-related quality of life and depression symptoms scores. Cox regression was used for association of physical activity with mortality. RESULTS: The median (interquartile range) of follow-up was 1.6 (0.9-2.5) years; 29% of patients were classified as never/rarely active, 20% of patients were classified as very active, and 20.5% of patients reported strength/flexibility activities. Percentages of very active patients were greater in clinics offering exercise programs. Aerobic activity, but not strength/flexibility activity, was associated positively with health-related quality of life and inversely with depression symptoms and mortality (adjusted hazard ratio of death for very active versus never/rarely active, 0.60; 95% confidence interval, 0.47 to 0.77). Similar associations with aerobic activity were observed in strata of age, sex, time on dialysis, and diabetes status. CONCLUSIONS: The findings are consistent with the health benefits of aerobic physical activity for patients on maintenance hemodialysis. Greater physical activity was observed in facilities providing exercise programs, suggesting a possible opportunity for improving patient outcomes.

Physical function and physical activity assessment and promotion in the hemodialysis clinic: a qualitative study.

BACKGROUND: Despite practice guidelines (KDOQI [Kidney Disease Outcomes Quality Initiative]) recommending regular assessment of physical function and encouragement of physical activity, few clinics in the United States objectively assess physical function/physical activity or provide recommendations for physical activity in their patient care. STUDY DESIGN: Qualitative methods were used to develop an understanding of practice patterns related to physical function assessment and physical activity encouragement by dialysis staff. SETTING & PARTICIPANTS: Data were collected in one outpatient university-based hemodialysis clinic. 15 patient care staff were interviewed and 6 patients were observed. METHODOLOGY: Semistructured interviews of patient care staff were conducted, along with nonparticipant observations of the clinic environment and operations and review of archival materials. ANALYTIC APPROACH: Coding of the interviews was descriptive, followed by interpretive coding by the research team. On-site field notes were transcribed for analysis. RESULTS: There was universal unawareness of the KDOQI guideline related to physical function/physical activity; however, all staff thought their patients would benefit from physical activity. There were no objective assessments of physical function and no resources or training to facilitate physical activity encouragement. Staff described deteriorating physical function in their patients, which was frustrating and disappointing. Barriers to physical activity included clinical/disease factors, staff "overaccommodation," and a system of dialysis care that facilitates sedentary behavior and does not require or incentivize clinics to promote physical activity. The patient care technicians were interested and thought that they had time to promote physical activity, but thought that they were unprepared to do so, indicating a need for education and training and a need to develop protocols to address the issue as routine practice. LIMITATIONS: This was a single university-based center; however, because hemodialysis procedures are prescribed by Centers for Medicare & Medicaid Services regulations, it is likely that practice in this clinic is representative of nationwide practice. CONCLUSIONS: Development of strategies to implement practice change that addresses low physical function and physical activity is warranted.

The association of physical activity and physical function with clinical outcomes in adults with chronic kidney disease.

PURPOSE OF REVIEW: Despite guidelines supporting the regular assessment of physical functioning and encouragement of physical activity in management of the patient with chronic kidney disease (CKD), implementation has been undermined by a lack of understanding of the evidence for this recommendation. The purpose of this review is to present a summary of emerging data from larger epidemiologic cohorts that report associations between low levels of physical functioning and/or low physical activity and clinical outcomes in patients with CKD. RECENT FINDINGS: Low levels of physical activity and poor physical functioning are strongly associated with mortality and poor clinical outcomes in adult patients with CKD, regardless of treatment modality. Low physical performance and activity limitations are more prevalent in patients with CKD, regardless of age, compared to older community-dwelling adults. SUMMARY: The strength of the evidence presented should strongly motivate a focus of treatment on assessing and improving physical activity and physical function as part of routine patient-centered management of persons with CKD. Physical activity interventions are warranted because patients with CKD, regardless of age, have a high prevalence of low physical functioning and frailty that is similar to or higher than the general population of elderly adults; physical activity, physical function, and performance are strongly associated with all-cause mortality; and exercise training and exercise counseling have been shown to improve measures of physical functioning.

Effects of the left ventricular assist device on the compliance and distensibility of the carotid artery.

We investigated the impact of continuous-flow left ventricular assist devices (LVAD) on the carotid elastic properties. Carotid artery parameters (diameter distensibility (DD), cross-sectional distensibility (CSD), diameter compliance (DC), cross-sectional compliance (CSC), and incremental elastic modulus (IEM)) were measured in a cross-sectional study using a standard ultrasound with a 10-MHz linear array probe. Measurements (mean ± SEM) were made in separate groups at various clinical time points: prior to LVAD surgery (baseline; 13 male/3 female; age 48 ± 3 years), 1 week following LVAD placement (acute; 12 male/2 female; age 47 ± 3 years), approximately 24 weeks following LVAD surgery (chronic; 13 male/2 female; age 52 ± 3 years), and in a group of healthy subjects (controls; 9 male/1 female; age 51 ± 4 years). Distensibility properties were lower (P < 0.05) in the acute (DD 2.3 % ± 0.4 %; CSD 4.7 % ± 0.8 %) and chronic (DD 2.2 % ± 0.4 %; CSD 4.5 ± 0.9 %) compared with the baseline (DD 5.9 % ± 0.7 %; CSD 12.2 % ± 1.5 %) and control (DD 5.8 % ± 0.6 %; CSD 11.9 % ± 1.3 %) groups. Compliance properties were lower (P < 0.05) in the chronic (DC 4.4 ± 0.7 mm/mmHg × 10(-3); CSC 1.2 ± 0.2 mmHg(-1) × 10(-3)) compared with acute (DC 9.0 ± 1.6 mm/mmHg × 10(-3); CSC 2.6 ± 0.4 mmHg(-1) × 10(-3)) and baseline (DC 11.1 ± 1.1 mm/mmHg × 10(-3); CSC 3.3 ± 0.4 mmHg(-1) × 10(-3)) groups. The compliance properties in the control (DC 8.3 ± 0.8 mm/mmHg × 10(-3); CSC 2.4 ± 0.2 mmHg(-1) × 10(-3)) group were not different from any of the patient groups. The IEM was higher (P < 0.05) in the chronic (6908 ± 1269 mmHg) compared with acute (2739 ± 412 mmHg), baseline (1849 ± 177 mmHg), and control (2349 ± 241 mmHg) groups. Chronic continuous-flow LVAD support is associated with lower carotid artery compliance and distensibility, which may place further strain on the left ventricle.

Assessing physical function and physical activity in patients with CKD.

Patients with CKD are characterized by low levels of physical functioning, which, along with low physical activity, predict poor outcomes in those treated with dialysis. The hallmark of clinical care in geriatric practice and geriatric research is the orientation to and assessment of physical function and functional limitations. Although there is increasing interest in physical function and physical activity in patients with CKD, the nephrology field has not focused on this aspect of care. This paper provides an in-depth review of the measurement of physical function and physical activity. It focuses on physiologic impairments and physical performance limitations (impaired mobility and functional limitations). The review is based on established frameworks of physical impairment and functional limitations that have guided research in physical function in the aging population. Definitions and measures for physiologic impairments, physical performance limitations, self-reported function, and physical activity are presented. On the basis of the information presented, recommendations for incorporating routine assessment of physical function and encouragement for physical activity in clinical care are provided.

A closer look at frailty in ESRD: getting the measure right.

Patients treated with dialysis have low levels of physical functioning and activity. Whether this translates into frailty or not may depend on how the frailty phenotype is operationalized. This is a secondary analysis of data from the Renal Exercise Demonstration Project to evaluate two methods of operationalizing the Fried phenotype for frailty: Using measured walking speed and muscle weakness (FRAILmeas) and using substitution of the Physical Function Scale (PF) from the SF-36 questionnaire for walking speed and muscle weakness (FRAILsubst). Complete data for both measures were available for 188 hemodialysis patients. The frailty score (FRAILmeas) was the sum of criteria scores for measured gait speed, chair stand, body mass index, vitality, and physical activity. The frailty score (FRAILsubst) substituted the PF scale score (<75) as a surrogate measure for gait speed and for weakness. The frailty score ranged from 0 to 5. Scores ≥3 were categorized as frail, and <3 as not frail. The substitution of the PF score for walking speed and muscle weakness resulted in 78% of patients being categorized as frail compared to 24% using actual measured walking speed and muscle weakness (P < .001). The component of frailty that had the highest prevalence was low physical activity (average 54% of subjects). Frailty (using the FRAILmeas) was higher in patients with increasing age, female gender, and lower self-reported PF. Frailty is highly prevalent in hemodialysis patients; however, measured constructs of the components of frailty should be used to report the frailty phenotype.

Physical function and gait speed in patients with chronic kidney disease.

Patients with chronic kidney disease (CKD) who are treated with dialysis have impaired physical functioning that is associated with poor outcomes. Gait speed is an important measure of mobility that predicts adverse events and mortality in older people. Gait speed is low in patients with CKD, and those treated with hemodialysis average below cut-points known to indicate increased risk of reduced survival and adverse health events. Measurement of gait speed in patients with CKD may be valuable in identifying those at risk for adverse events, including disability and mortality.

Effects of modality change on health-related quality of life.

Patients with end-stage renal disease (ESRD) requiring renal replacement have impaired health-related quality of life (HRQoL), and there is general consensus that HRQoL improves with successful transplant and evidence of improvement with frequent hemodialysis. This study reports changes in HRQoL associated with changes in treatment modality to daily hemodialysis (DHD) and transplant among patients requiring renal replacement. This cohort study had assessments at baseline and 6-month following modality change. Subjects were nondiabetic individuals receiving conventional hemodialysis who (a) remained on conventional hemodialysis (n = 13), (b) changed to daily hemodialysis (DHD) (n = 10), or (c) received a living donor transplant (n = 20). Thirty-four healthy controls were assessed once for comparison. HRQoL was measured using the Kidney Disease Quality of Life Instrument. The Physical Functioning and Physical Composite Scale scores were primary outcomes. Transplantation resulted in significant improvements in six of eight generic scales and the physical composite scale (PCS). Those changing to DHD had significant improvements in Physical Function and PCS scales. Those remaining on dialysis remained lower than controls on all scales except for Vitality; the transplant group remained lower than controls only on the Vitality and General Health scales. Transplant resulted in significant improvements in four of the seven disease-specific scales (symptoms, effects, and burden of kidney disease, work). DHD resulted in improvements in the effects of kidney disease. Modality change to transplant results in significant improvement in HRQoL, achieving levels similar to controls. Change to daily hemodialysis improves only select HRQoL domains and remains low in disease-specific domains.

Effects of six versus three times per week hemodialysis on physical performance, health, and functioning: Frequent Hemodialysis Network (FHN) randomized trials.

BACKGROUND AND OBJECTIVES: Relatively little is known about the effects of hemodialysis frequency on the disability of patients with ESRD. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This study examined changes in physical performance and self-reported physical health and functioning among subjects randomized to frequent (six times per week) compared with conventional (three times per week) hemodialysis in both the Frequent Hemodialysis Network daily (n=245) and nocturnal (n=87) trials. The main outcome measures were adjusted change in scores over 12 months on the short physical performance battery (SPPB), RAND 36-item health survey physical health composite (PHC), and physical functioning subscale (PF) based on the intention to treat principle. RESULTS: Overall scores for SPPB, PHC, and PF were poor relative to population norms and in line with other studies in ESRD. In the Daily Trial, subjects randomized to frequent compared with conventional in-center hemodialysis experienced no significant change in SPPB (adjusted mean change of -0.20±0.19 versus -0.41±0.21, P=0.45) but experienced significant improvement in PHC (3.4±0.8 versus 0.4±0.8, P=0.009) and a relatively large change in PF that did not reach statistical significance. In the Nocturnal Trial, there were no significant differences among subjects randomized to frequent compared with conventional hemodialysis in SPPB (adjusted mean change of -0.92±0.44 versus -0.41±0.43, P=0.41), PHC (2.7±1.4 versus 2.1±1.5, P=0.75), or PF (-3.1±3.5 versus 1.1±3.6, P=0.40). CONCLUSIONS: Frequent in-center hemodialysis compared with conventional in-center hemodialysis improved self-reported physical health and functioning but had no significant effect on objective physical performance. There were no significant effects of frequent nocturnal hemodialysis on the same physical metrics.

Exercise in individuals with CKD.

There are few studies evaluating exercise in the nondialysis chronic kidney disease (CKD) population. This review covers the rationale for exercise in patients with CKD not requiring dialysis and the effects of exercise training on physical functioning, progression of kidney disease, and cardiovascular risk factors. In addition, we address the issue of the risk of exercise and make recommendations for implementation of exercise in this population. Evidence from uncontrolled studies and small randomized controlled trials shows that exercise training results in improved physical performance and functioning in patients with CKD. In addition, although there are no studies examining cardiovascular outcomes, several studies suggest that cardiovascular risk factors such as hypertension, inflammation, and oxidative stress may be improved with exercise training in this population. Although the current literature does not allow for definitive conclusions about whether exercise training slows the progression of kidney disease, no study has reported worsening of kidney function as a result of exercise training. In the absence of guidelines specific to the CKD population, recent guidelines developed for older individuals and patients with chronic disease should be applied to the CKD population. In sum, exercise appears to be safe in this patient population if begun at moderate intensity and increased gradually. The evidence suggests that the risk of remaining inactive is higher. Patients should be advised to increase their physical activity when possible and be referred to physical therapy or cardiac rehabilitation programs when appropriate.

Bioimpedance spectroscopy for the estimation of fat-free mass in end-stage renal disease.

BACKGROUND #ENTITYSTARTX00026; AIMS: Bioimpedance spectroscopy may provide reliable estimates of fat-free mass in end-stage renal disease patients. We aimed to evaluate the ability of bioimpedance spectroscopy to estimate fat-free mass in end-stage renal disease patients using dual-energy X-ray absorptiometry as a reference. METHODS: Fat-free mass measured by bioimpedance spectroscopy was compared to fat-free mass measured by dual-energy X-ray absorptiometry in 16 end-stage renal disease patients on hemodialysis, 12 undialysed end-stage renal disease patients and 23 control subjects. RESULTS: Methods were highly correlated for fat-free mass in all subject groups (r = 0.87, P < 0.001). Mean bioimpedance spectroscopy measures of fat-free mass were not different from the dual-energy X-ray absorptiometry measures in any subject group. Individual comparisons revealed wide limits of agreement between methods in hemodialysis (11.6 to -9.72 kg) and undialysed patients (10.95 to -14.73 kg). CONCLUSIONS: Although bioimpedance spectroscopy estimates of fat-free mass in the end-stage renal disease patient groups were not different from dual-energy X-ray absorptiometry and the methods were highly correlated, there was great individual variability. From these data it is clear that future studies are warranted before bioimpedance spectroscopy can be recommended as a valid clinical tool for assessing fat-free mass in end-stage renal disease patients.

Self-reported physical activity in patients with end stage renal disease.

Patients served by ESRD Network 11 were surveyed on participation in regular physical activity (physical activity). National recommendations (3 days/week, 30 minutes/session, and intensity of "moderate level") were used to categorize respondents into three physical activity categories: no physical activity, some physical activity, and recommended levels of physical activity. Analysis of 1323 returned questionnaires indicated that 57% of respondents reported participation in regular physical activity; however, only 13.2% achieved recommended levels based on frequency, duration, and intensity. The primary reasons for no physical activity were '"too tired" and "not motivated." The most frequently cited benefits in those who reported regular physical activity were "increased energy," "increased muscle strength," and "enhanced ability to do things needed in life." Fifty-seven percent reported they had "been talked to about exercise;" only 34% received any written information on initiating physical activity. Greater effort to incorporate education and motivation into the routine care is warranted to increase physical activity to levels that may result in health benefits.

Effects of modality change and transplant on peak oxygen uptake in patients with kidney failure.

BACKGROUND: Exercise capacity as measured by peak oxygen uptake (Vo2(peak)) is low in hemodialysis patients. The present study assesses determinants of VO2(peak) in patients with chronic kidney failure who either changed kidney replacement modality to frequent hemodialysis therapy or received a kidney transplant. STUDY DESIGN: Cohort study with assessment at baseline and 6 months after modality change. SETTING & PARTICIPANTS: Participants included nondiabetic individuals receiving conventional hemodialysis who: (1) remained on conventional hemodialysis therapy (n = 13), (2) changed to short daily hemodialysis therapy (n = 10), or (3) received a transplant (n = 5) and (4) individuals who underwent a pre-emptive transplant (n = 15). Additionally, 34 healthy controls were assessed at baseline only. PREDICTOR: Modality change. MEASUREMENT & OUTCOMES: Exercise capacity, assessed using the physiologic components of the Fick equation (Vo2 = cardiac output × a-vo2(dif), where a-vo2(dif) is arterial to venous oxygen difference) was determined using measurement of Vo2(peak) and cardiac output during symptom-limited exercise testing. Analysis of covariance was used to compare differences in changes in Vo2(peak), cardiac output, heart rate, stroke volume, and a-vo2(dif) at peak exercise between participants who remained on hemodialysis therapy and those who underwent transplant. RESULTS: Transplant was the only modality change associated with a significant change in Vo2(peak), occurring as a result of increased peak cardiac output and reflecting increased heart rate without a change in peak a-vo2(dif) despite increased hemoglobin levels. There were no differences in participants who changed to daily hemodialysis therapy compared with those who remained on conventional hemodialysis therapy. LIMITATIONS: Small nonrandomized study. CONCLUSIONS: Vo2(peak) increases significantly after kidney transplant, but not with daily hemodialysis; this improvement reflects increased peak cardiac output through increased peak heart rate. Despite statistical significance, the increase in Vo2(peak) was not clinically significant, suggesting the need for interventions such as exercise training to increase Vo2(peak) in all patients regardless of treatment modality.