Physical Functioning and Health-Related Quality-of-Life Changes With Exercise Training in Hemodialysis Patients Patricia Painter, PhD, Laurie Carlson, RN, MSN, Susan Carey, MS, Steven M. Paul, PhD, and Jeffrey Myll, MS ● The Renal Exercise Demonstration Project was designed to test the effects of two different approaches to exercise programming on the levels of physical activity, physical functioning, and self-reported health status in hemodialysis patients. Two hundred eighty-six patients were recruited for participation. Intervention patients were given individually prescribed exercise for 8 weeks of independent home exercise, followed by 8 weeks of incenter cycling during dialysis. Physical performance testing was performed at baseline and after each intervention using gait speed, sit-to-stand test, and 6-minute walk. The Medical Outcomes Study Short Form 36-item (SF-36) questionnaire was used to assess self-reported health status. The intervention group showed increased participation in physical activity. There were significant differences between the intervention and nonintervention groups in change over time in normal and fast gait speed, sit-to-stand test scores, and the physical scales on the SF-36, including the physical component scale. The intervention group improved in these test results, whereas the nonintervention group either did not change or declined over the duration of the study. It is clear that improvements in physical functioning result from exercise counseling and encouragement in hemodialysis patients. Because self-reported physical functioning is highly predictive of outcomes in hemodialysis patients, more attention to patients’ levels of physical activity is warranted. 娀 2000 by the National Kidney Foundation, Inc. INDEX WORDS: Physical functioning; exercise training; quality-of-life; physical activity; hemodialysis.
HE IMPORTANCE of physical activity has been clearly stated in the 1996 US Surgeon General’s publication, Physical Activity and Health.1 This document concluded that people of all ages, both males and females, benefit from moderate levels of physical activity. The report also presented evidence of the benefits of physical activity on health and disease: specifically, reduction of risk for cardiovascular disease; prevention or delay in the development of hypertension and reduction of blood pressure in those with hypertension; maintenance of normal muscle strength, joint structure, and function; preservation of the ability to maintain independent living status, and reduction of the risk for falling in the elderly; relief of symptoms of depression and anxiety and improving mood; and improvement
From the University of California at San Francisco, Department of Physiological Nursing, San Francisco, CA; and the Stanford Center for Research in Disease Prevention, Palo Alto, CA. Received June 28, 1999; accepted in revised form September 24, 1999. Supported in part by Amgen Clinical Research Program; Dialysis Clinics, Inc; Satellite Dialysis Centers, Inc; and Total Renal Care, Inc. Address reprint requests to Patricia Painter, PhD, Box 0116 UCSF, San Francisco, CA 94143-0116. E-mail: [email protected]
娀 2000 by the National Kidney Foundation, Inc. 0272-6386/00/3503-0015$3.00/0 482
in health-related quality of life by enhanced psychological well-being and by improvement in physical functioning in persons compromised by poor health. Although the Surgeon General’s report, Physical Activity and Health, does not specifically mention patients with end-stage renal failure, many of the secondary conditions highly prevalent in these patients are positively affected by increased physical activity. In addition to these benefits, increased physical activity in the hemodialysis population may have even more significant implications in terms of physical functioning. Objectively measured exercise capacity is low in hemodialysis patients.2-10 Self-reported physical functioning in these patients is also low and similar to that of patients with congestive heart failure and obstructive pulmonary disease.11 Self-reported physical functioning is more closely linked to outcomes in hemodialysis patients than other commonly measured mortality predictors, such as case mix, adequacy of dialysis, albumin level, and so on.12,13 Exercise training increases objective measures of exercise capacity.2,5,9,10 No studies have reported the effects of exercise training on selfreported physical functioning. However, if exercise training results in improved self-reported physical functioning, it could have a positive impact on outcomes. Most exercise studies of hemodialysis patients have included younger, higher functioning pa-
American Journal of Kidney Diseases, Vol 35, No 3 (March), 2000: pp 482-492
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tients with few (if any) comorbidities who were able to perform rigorous laboratory testing. Thus, the exercise capacity of the majority of dialysis patients is probably even less than the values reported in the literature. No studies have objectively reported physical functioning levels of those patients who are more frail, with more comorbidities, and thus who are more representative of the general dialysis population. Recent studies of geriatric populations have shown the value of using standardized physical performance tests in evaluating physical functioning in patients who are older and more frail and unable to perform rigorous laboratory testing.14-16 The Renal Exercise Demonstration Project (REXDP) was a response to a request for proposals by the Life Options Advisory Council and Amgen, Inc. It was designed to test the effects of two different approaches to exercise programming on the levels of physical activity, physical functioning, and self-reported health status in hemodialysis patients. The two programming approaches were independent home exercise (IND) and incenter cycling (ICC) exercise.17 The demonstration project was designed to assess the feasibility and effectiveness of the interventions in freestanding, nonresearch clinics using existing dialysis staff to assist in monitoring patient activity (independent exercise) and facilitate the participation in the ICC program. Additionally, we aimed to include a wide range of patients and to use testing measures of physical functioning that can be easily administered by dialysis professionals within the dialysis clinic. METHODS
Study Design The demonstration project was designed to evaluate an 8-week intervention of individually prescribed independent exercise to be performed at home (IND), followed by an 8-week intervention of cycling during the dialysis treatment (ICC).
Dialysis Staff Training The project was presented to the dialysis staff in each of the sponsoring providers’ units by the project personnel. The staff then voted whether they wanted to participate. It was preferred that at least 75% of the staff vote in favor before starting the project. The project was performed in five clinics in the San Francisco Bay area. A staff inservice training session was held prior to contact with patients. The staff assisted the project personnel in developing mechanisms for incorporation of the exercise into the patient care plan and
for tracking patient activity that would fit into the routine care of patients in each unit. Staff also assisted the project personnel in developing motivational activities for both patients and staff.
Patient Recruitment The philosophy and experience of the investigators is that most patients can do some type of activity. Some may only be able to tolerate range-of-motion and/or strengthening exercise, whereas others can tolerate the initiation of cardiovascular exercise and progress to levels of activity within the range recommended for health by the Surgeon General’s report (ie, three times weekly, 30 min/session of such moderate activity as walking or cycling). Thus, the goal was to include a wide range of patients in terms of age and clinical conditions. There was no upper age limit to participation, and the exclusion criteria were exertional angina, angina at rest, lower extremity amputation with no prosthesis, orthopedic disorder exacerbated by activity, chronic lung disease that resulted in significant desaturation with exercise or shortness of breath at rest, and cerebral vascular disease manifested by transient ischemic attacks. Patients had to be on dialysis therapy for at least 3 months. Patients were recruited by the project staff (registered nurse and exercise physiologist), and consent was obtained according to procedures approved by the Committee on Human Research at the University of California at San Francisco and Davis and the Institutional Review Board of Dialysis Clinics, Inc. Physician permission was also obtained before participation of any patient who consented to participate. Intervention units were clinics in the San Francisco Bay area owned by supplemental sponsors of the project. The intervention units were chosen if the nurse manager expressed an interest and at least 75% of the dialysis staff expressed interest in participation. The control unit was one in which the nurse managers were interested in the project, but in which the staff was not willing to participate. In the control unit, only patient testing was performed at baseline and twice at 2-month intervals, with no intervention. All control patients were given recommendations for exercise after the final testing session.
Physical Function Testing Three well-established performance-based physical function tests were used to assess changes in measured physical functioning. Gait speed was measured over 20 feet. The distance was timed during a comfortable pace and again at maximum walking pace for each subject. The gait speed is expressed in centimeters per second to compare with normative values presented by Bohannon.18 The sit-to-stand-to-sit test was used to assess lower extremity muscle strength.19-21 This test was performed as described by Csuka and McCarty,20 in which patients were instructed to stand up from a seated position and sit back down 10 times from a chair of standardized height. The time required to complete 10 cycles was recorded. The result was standardized as a percentage of age-predicted value using the following prediction formulas developed by Csuka and McCarty20:
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Women, time (seconds) ⫽ 7.6 ⫹ 0.17 ⫻ age Men, time (seconds) ⫽ 4.9 ⫹ 0.19 ⫻ age The 6-minute walk included the distance covered in 6 minutes on an established walking course and was also part of the testing.22-27 The patients were instructed to cover as much distance as possible in the 6 minutes. They were allowed to stop and take breaks if needed. A staff member timed the patient, encouraged them consistently, and accompanied those who appeared to be less stable in walking. Patients requiring assistive devices were included in the testing, and the use of the device was documented. The test results are reported as the distance covered in feet. The number of patients unable or unwilling to attempt this test was significant, thus reducing the utility of the results of this test.
Health-Related Quality of Life The Medical Outcomes Study Short Form 36-item (SF36) questionnaire was used to evaluate self-reported domains of health status.28,29 This questionnaire has 36 items compiled into eight scales: physical functioning (PF), role functioning/physical (RP), bodily pain (BP), general health (GH), vitality (VT), social functioning (SF), role functioning/ emotional (RE), and mental health (MH). These scales are scored from 0 to 100; a higher score is more positive (ie, less pain or less limitation). Normalized scores representing overall physical functioning and mental functioning are calculated from the individual scales and are presented as the physical component scale (PCS) and the mental component scale (MCS). The PCS includes the dimensions of PF, RP, BP, GH, VT, and SF. The MCS is composed of the RE and MH, and includes elements of the GH, VT, and SF scales, as well.30 The questionnaires were completed independently during dialysis by those patients capable of doing so. Patients unable to complete them independently because of vision, language, or other reasons were administered the questionnaires by the study staff during the dialysis treatment.
Physical Activity Characterization Patient levels of physical activity were assessed from self-report and categorized into the following levels: (1) activities of daily living (ADLs) only, in which there was no participation of any additional activities; (2) stretching or strengthening activity; (3) low cardiovascular exercise (some CV), in which patients reported some cardiovascular exercise (ie, walking or cycling) at a level less than that recommended by the Surgeon General’s report (ie, ⬍ three times weekly and/or ⬍20 min/session); and (4) recommended cardiovascular exercise (rec CV), in which patients reported participation in regular cardiovascular exercise at least three times weekly for 20 minutes or more per session.
Interventions All exercise was individually prescribed by the study staff. The recommendations were then written out for each patient and included specific exercises, frequency, intensity, duration, and progression. Additionally, each patient was
given the Dialysis Patient’s Guide to Exercise,17 from which the precautions for exercise were carefully reviewed. Dialysis staff was expected to record exercise at the time of the predialysis assessment at every treatment. In each unit, the dialysis flow sheet was modified to include a place for recording exercise that required the staff member to circle yes or no at the exercise question and enter the number of minutes of participation reported by the patients. For those in the project, exercise was included in the dialysis orders. Because of very low rates of completion of this assessment by the dialysis staff, participation was determined by patient self-report at the time of each testing session. IND. Each patient enrolled on the project was given an individualized program of exercise to follow at home. This program consisted of flexibility, strengthening, and cardiovascular exercises. The specific exercises for both flexibility and strengthening were those described in the Dialysis Patients’ Guide to Exercise.17 The recommendation for flexibility exercises was for 5 to 6 days weekly. The strengthening recommendation was for a frequency of three times weekly, starting at one set of 10 repetitions of each exercise using 1- to 2-lb weights and increasing according to tolerance to three sets of 15 repetitions, at which time the weight was increased by 1 to 2 lb. The recommendations for cardiovascular exercise were for 3 to 4 days weekly. The activity recommended was primarily walking, although some used a stationary cycle at home, and some purchased a videotape for chair exercises. The starting point was determined by how long (or far) the patient could tolerate the activity. The patients were instructed to start at this duration and gradually increase the time or distance of the activity by 2 to 3 minutes each day. Most patients were given guidelines on the intensity of exercise using a modified (5-point) rating of perceived exertion scale (rest ⫽ 0, easy ⫽ 1, medium hard ⫽ 2, hard ⫽ 3, very hard ⫽ 4). Those who were more fit were instructed on warm-up and cooldown intensities, although most patients were focused on gradually increasing duration at whatever intensity they could tolerate. Each patient was given a log to complete on their own and written instructions on how to progress their program. Patients continued with their independent exercise for 2 months. ICC. The ICC program consisted of using stationary cycles modified for use from the dialysis chair (ChampCycle; Champion Manufacturing, Elkhart, IN). The dialysis staff was instructed on the setup of the cycle for patients during their treatment and were expected to bring the cycle to the patients who were in the program. The patients were started on the cycle by the study staff, and each was given a program to follow independently. The first session determined their tolerance for the cycling and their starting duration. They were instructed to increase the duration gradually by 2 to 3 minutes each session (according to tolerance) and how to adjust the intensity of exercise (increasing tension on the pedals and/or increasing pedal speed) using the rating of perceived exertion scale. The goal of the cycling was to work up to 30 minutes of continuous cycling during every dialysis session. Patients were encouraged to continue their strengthening and stretching exercises at home.
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Data Analysis Means and SDs for the quantitative variables and frequencies and percentages for the categorical variables were generated for all baseline demographic and clinical data. Repeated-measures analysis of variance (ANOVA) with one between-subjects factor (group with two levels) and one within-subjects factor (time, with three levels) was used to determine the impact of the intervention.
Subjects Two hundred eighty-six patients consented to participate in the project. Table 1 shows the clinical and demographic characteristics of patients recruited into the intervention and nonintervention groups. There were no statistically significant differences between the two groups in any of these characteristics. Ethnicity was 31.8% white, 24.1% Hispanic, 26.6% black, 15.0% Asian, 8.4% Pacific Islanders, and 3.0% other. The causes of renal failure were diabetes mellitus (43.7%), hypertension (25.2%), glomerulonephritis (7.7%), systemic lupus erythematosus or polycystic kidney disease (5.2%), unknown (4.5%), and other (11.9%). Thirty-eight intervention patients were lost to the project between baseline and IND for the following reasons: death (10 patients), transplantation (6 patients), relocation or change to peritoneal dialysis (11 patients), disinterest (2 patients), and medical complications (10 patients). An additional 23 patients were lost between IND and ICC because of death (3 patients), transplantation (2 patients), disinterest (2 patients), and medical complications (16 patients). No controls were lost to the study. Table 1. Baseline Characteristics
Age (y) 55.9 ⫾ 15.15 52.8 ⫾ 16.8 Women (%) 57.1 65.4 No. of comorbid conditions 3.0 ⫾ 1.4 2.6 ⫾ 1.7 Dialysis adequacy (Kt/V) 1.6 ⫾ 0.46 1.5 ⫾ 0.38 Hematocrit (%) 33.6 ⫾ 4.5 35.0 ⫾ 1.6 Albumin (mg/dL) 3.7 ⫾ 0.39 4.0 ⫾ 0.35 Dialysis prescription (min/wk) 526.4 ⫾ 94.1 533.5 ⫾ 86.9 Time on dialysis (mo) 33.7 ⫾ 35.6 40.2 ⫾ 62.4 NOTE. Values expressed as mean ⫾ SD. There were no differences between groups in any characteristics.
Not all patients completed all three tests and, at each test time, not all tests were complete. Because repeated-measures ANOVA includes only those subjects who completed all three test times, the sample sizes in the analysis are smaller than the total number of patients recruited onto the project. There were 131 patients who completed all tests for gait speed, 111 patients for the sit-to-stand test, and 44 patients for the 6-minute walk. Reasons for missing each test are listed in Table 2. Most clinics lacked space to perform the 6-minute walk inside; therefore, weather became an obstacle to performing this test. Physical Activity Status Figure 1 shows reported physical activity in the intervention group at each testing time. At baseline, 59% of the intervention group reported no physical activity beyond basic ADLs. Twentythree percent reported ‘‘some cardiovascular exercise,’’ which averaged 2.6 ⫾ 2.3 days weekly for 16.4 ⫾ 8.5 min/session. The percentage participating in cardiovascular exercise 3 days or more weekly for at least 30 min/session was 12%. These patients participated in 23.7 ⫾ 15.4 min/session of exercise 3.2 ⫾ 1.8 days weekly. The percentage of patients reporting an increase in activity (ie, moved from ADLs only to something more; from stretching/strengthening to some or rec CV; or from some CV to rec CV) was 61.1% from baseline to the end of the project. Twenty-one percent increased between IND and ICC. From baseline to IND, 17.4% did not change activity and 12.1% declined in activity levels. From IND to ICC, 37.6% did not change activity and 6.4% declined in their activity levels. The percentage of patients performing only ADLs decreased from 59% to 28% after IND and to 6.4% after ICC. On the higher end, those reporting cardiovascular exercise at the recommended levels increased from only 12% at baseline to 45% at the end of the study. The frequency of participation in cardiovascular exercise for all participants increased to an average of 4.1 ⫾ 1.1 days per week and duration to 38.4 ⫾ 9.0 min/session at the end of the study. Those initially reporting some CV exercise increased duration to 33.3 ⫾ 19.2 min/session and increased frequency to average 4.2 ⫾ 1.8 days per week. Those initially reporting rec CV exercise increased in frequency to 4.5 ⫾ 1.2 days
PAINTER ET AL Table 2. Reasons for Missed Physical Functioning Tests
Reasons for Missed Tests
No. of tests missed Amputation Medical† Orthopedic Refused Patient or staff schedules Weather
31 (12)* 6 (19) 10 (32) 7 (22) 4 (13)
53 (21)* 9 (16) 24 (45) 5 (9) 7 (13)
52 (23)* 7 (13) 19 (36) 8 (15) 8 (15)
64 (22)* 5 (7.8) 22 (34) 10 (16) 5 (8)
77 (31)* 9 (12) 28 (36) 13 (8) 9 (12)
90 (40)* 9 (10) 26 (29) 21 (23) 9 (10)
142 (49)* 7 (5) 25 (18) 23 (16) 8 (6)
155 (62)* 9 (6) 31 (20) 25 (16) 9 (6)
145 (64)* 9 (6) 28 (19) 25 (17) 13 (9)
4 (13) —
10 (19) —
9 (17) —
19 (29) —
18 (23) —
25 (28) —
42 (29) 37 (26)
33 (21) 46 (29)
47 (32) 23 (16)
NOTE. Values expressed as number (percentage of total missed tests) unless otherwise noted. *Percentage of total patients in study at that time. †Recent hospitalization or other medical problem, including hypotension or hypertension, hypoglycemia, general malaise, flu, and access problems.
per week and in duration to 38.9 ⫾ 9.5 min/ session. At baseline, 76% of the nonintervention group reported ADLs only, with 7.7% participating in rec CV. Reported activity did not change in the nonintervention group. Physical Function Tests There were a significant number of missed physical function tests. Overall, 51% of all the tests were completed at the end of the study
(compared with 75% of questionnaires completed). The reasons for missing tests were many and are listed in Table 2. Medical concerns and orthopedic limitations were the primary reasons for not performing tests. However, for the 6-minute walk, which had the most missing tests, patient or staff schedules were cited more frequently than for the other two tests. Weather was also a problem in completing the walk test because most clinics did not have adequate space to perform the test indoors. Rain and hot weather both prevented completion of this part of the testing for many patients. Gait Speed
Fig 1. Physical activity participation at each testing time. (L) Activities of daily living only, (䊐) calisthenics (stretching/strengthening exercises), (E) some cardiovascular exercise (F20 minutes and/or F3 times per week), (䊏) recommended cardiovascular exercise (G20 min/session H times/wk).
The gait speed test had the highest completion rate of the three physical function tests. One hundred thirty-one patients completed the gait speed test at all three testing sessions. The baseline normal gait speed for these subjects averaged 90.5 ⫾ 25.6 cm/s, which is 66.1% ⫾ 17.5% of normal age-expected values reported by Bohannon.18 The test of the group by time interaction of the repeated-measures ANOVA indicated that the change over time was different between the intervention and nonintervention groups (F2,160 ⫽ 3.89; P ⫽ 0.021; Fig 2), with the intervention group improving and the nonintervention group declining over the project time. The intervention group increased from 66% to 69% of age-expected norms, whereas the nonintervention group decreased from 66% to 59% of normal values by the end of the study.
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gait speed, with the intervention group increasing somewhat and the nonintervention group decreasing. The differences in change over time between the two groups was significant (F2,127 ⫽ 8.48; P ⬍ 0.001; Fig 2). The intervention group ended the study at 66% ⫾ 15% of normal values, whereas the nonintervention group decreased to 51% ⫾ 11% of normal. Sit-to-Stand-to-Sit Test One hundred eleven patients completed the sit-to-stand-to-sit test at all three testing sessions. The sit-to-stand-to-sit test score for these subjects at baseline was 29.3 ⫾ 12.5 seconds. This was only 15% ⫾ 30% of normal predicted values reported by Csuka and McCarty.20 The change over time was different between the intervention and nonintervention groups (F2,109 ⫽ 8.44; P ⫽ 0.050), with the intervention group improving over time and the control subjects not showing a change (Fig 2). The intervention group increased from 14% ⫾ 37% of normal to 38% ⫾ 37% of normal values, whereas the nonintervention group remained at 23% ⫾ 66% of normal values. Six-Minute Walk Test Only 44 patients in the intervention group and 5 patients in the nonintervention group completed all three 6-minute walk tests. The betweengroup comparison of the 6-minute walk test results was not performed because of the significant number of missing tests. Although the number of patients in the intervention group who completed all three tests was low, there was significant improvement in the distance covered, from 1,138.5 ⫾ 417 ft at baseline to 1,226.2 ⫾ 349 ft at the end of the study (P ⫽ 0.050). Health-Related Quality of Life
Fig 2. Results of physical function tests (PFT). (䊐) Intervention group, (䉫) nonintervention group. P are for the interaction of group over time. Values expressed as mean ⴞ SD. Abbreviation: ns, not significant.
The baseline fast gait speed was 133.4 ⫾ 37.6 cm/s at baseline in all subjects. This was 64% ⫾ 16% of normal values. The changes over time in the two groups were similar to those of normal
Scale scores (mean ⫾ SD) for the SF-36 for both groups at each testing time are listed in Table 3. Significant differences were noted in the change over time between the intervention and nonintervention groups in the physical scales: the group-by-time interactions were significant for PF (F2,201 ⫽ 5.69; P ⫽ 0.004), RP (F2,196 ⫽ 11.12; P ⬍ 0.001), GH (F2,197 ⫽ 2.91; P ⫽ 0.05), and BP (F2,200 ⫽ 5.7; P ⫽ 0.003). In all cases, the intervention group had increased self-reported physical scale scores, whereas the nonin-
PAINTER ET AL Table 3. SF-36 Scale Scores in the Intervention and Nonintervention Groups at Each Testing Time P
Physical functioning (n ⫽ 180)
Intervention Nonintervention Intervention Nonintervention Intervention Nonintervention Intervention Nonintervention Intervention Nonintervention Intervention Noninvertention Intervention Nonintervention Intervention Nonintervention Intervention Nonintervention Intervention Nonintervention
47.7 ⫾ 28.3 50.2 ⫾ 24.1 40.4 ⫾ 40.3 62.5 ⫾ 44.2 45.0 ⫾ 21.9 44.7 ⫾ 19.7 60.5 ⫾ 28.1 68.8 ⫾ 25.9 46.5 ⫾ 23.4 45.0 ⫾ 26.2 67.2 ⫾ 27.6 75.0 ⫾ 25.3 64.0 ⫾ 41.8 72.7 ⫾ 41.9 71.5 ⫾ 19.1 73.5 ⫾ 16.5 35.1 ⫾ 10.8 37.7 ⫾ 8.8 48.4 ⫾ 11.0 50.9 ⫾ 10.0
52.4 ⫾ 27.7 45.2 ⫾ 26.6 54.0 ⫾ 41.7 38.6 ⫾ 42.1 50.4 ⫾ 22.6 48.1 ⫾ 22.1 69.6 ⫾ 26.3 68.3 ⫾ 24.3 52.8 ⫾ 24.1 42.8 ⫾ 21.4 72.0 ⫾ 27.1 69.8 ⫾ 24.3 70.1 ⫾ 41.6 68.2 ⫾ 43.0 73.1 ⫾ 19.5 74.6 ⫾ 14.7 39.5 ⫾ 10.0 35.5 ⫾ 10.8 50.2 ⫾ 11.0 50.5 ⫾ 8.8
53.4 ⫾ 27.0 44.1 ⫾ 27.6 54.5 ⫾ 21.4 35.2 ⫾ 41.2 49.1 ⫾ 22.5 39.3 ⫾ 19.2 66.6 ⫾ 28.6 52.7 ⫾ 30.4 52.4 ⫾ 25.5 42.1 ⫾ 21.7 72.7 ⫾ 26.5 64.7 ⫾ 30.0 67.6 ⫾ 42.4 71.2 ⫾ 45.2 73.2 ⫾ 19.9 71.4 ⫾ 16.0 38.3 ⫾ 10.4 31.8 ⫾ 9.6 50.7 ⫾ 11.3 50.8 ⫾ 9.8
Role physical (n ⫽ 180) General health (n ⫽ 180) Bodily pain (n ⫽ 180) Vitality (n ⫽ 180) Social functioning (n ⫽ 180) Role emotional (n ⫽ 180) Mental health (n ⫽ 180) PCS (n ⫽ 180) MCS (n ⫽ 180)
NOTE. Values expressed as mean ⫾ SD. Abbreviations: IND, independent exercise; ICC, incenter exercise; PCS, physical component scale; MCS, mental component scale.
tervention group showed minimal change or decline in scale scores (Fig 3). No differences were noted in change over time between the intervention and nonintervention groups in the mental scales (Fig 4). The PCS was significantly different over time between the two groups (F2,177 ⫽ 10.7; P ⬍ 0.001; Fig 5). The intervention group improved and the nonintervention group declined in the scale score over the three testing sessions. DISCUSSION
Exercise training studies of hemodialysis patients have consistently reported significant increases in exercise capacity. These studies, however, only included patients able to complete a maximal treadmill test and perform vigorous training. No reported training study included older or more frail patients or those with known cardiac disease or diabetes. Thus, the generalizability of previous studies is limited because there is a high prevalence of cardiovascular disease (more than half the deaths in hemodialysis patients are caused by cardiac disease), 43% of hemodialysis patients have diabetes,31 and most are older and more frail, making them unable to
perform maximal exercise stress tests or train at exercise intensities required for training studies. The results of the REXDP are unique in the following ways. (1) A wide variety of patients were included who were more representative of the general hemodialysis population in terms of comorbidity and age. (2) The exercise prescribed was for exercise convenient for the patients, ie, no requirement to attend separate exercise training at a time other than their dialysis time. The independent exercise could be performed at home using available resources and on their own time. The incenter exercise did not add additional time requirements. (3) The testing was easily performed at the dialysis clinic and included physical performance testing, which tends to be less intimidating than maximal treadmill testing for older, more frail, or ill patients. (4) This is the first exercise study to report changes in healthrelated quality of life resulting from exercise counseling. Sixty-five percent of the patients enrolled on this demonstration project successfully incorporated changes in physical activity, and at the end of the project, 45% were exercising at a level recommended by the Surgeon General’s report,
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than performed at home independently. Despite minimal follow-up on the part of the exercise staff, it is impressive that just giving patients specific instructions on how to exercise will, for most, result in increased activity at home. This project was designed to have the exercise
Fig 3. SF-36 Physical Scale Scores. P are for the interaction of group over time. Values expressed as mean ⴞ SD. Abbreviations: PF, Physical Functioning; RP, Role Functioning/Physical; GH, General Health; BP, Bodily Pain; (䊐), intervention group; (䉫), nonintervention group.
Physical Activity and Health.1 The changes in activity resulted primarily from the independent exercise intervention. The incenter program led to longer duration of cardiovascular exercise
Fig 4. SF-36 Mental Scale Scores. P values are for the interaction of group over time. Values are expressed as mean ⴞ SD. Abbreviations: VT, Vitality; SF, Social Functioning; RE, Role Functioning/Emotional; MH, Mental Health; (䊐), intervention group; (䉫), nonintervention group.
Fig 5. SF-36 Physical and Mental Component Scale Scores. P are for the interaction of group over time. Values expressed as mean ⴞ SD. (䊐), Intervention group; (䉫), nonintervention group.
monitored by the dialysis staff. Thus, there was minimal interaction with the exercise professionals. We believe that more frequent interaction with the exercise professionals may have resulted in higher levels of participation and possibly greater improvements in physical functioning. More frequent interaction with an exercise professional would provide regular encouragement, progression with the program, and troubleshooting with patients who experience problems. Patients who have special concerns may benefit from a higher intensity of interaction with the exercise professionals to gain confidence in their ability to participate in higher levels of activity. It is possible that more participation may have resulted from more intensive training of the dialysis staff to counsel and troubleshoot problems. Staff training opportunities were very limited for this project. Additionally, allocation of more time for staff and incorporation of the ICC responsibilities into the job requirements of the staff would probably result in more consistent implementation of the cycling during dialysis, which may have resulted in further improvements with the ICC program.
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Despite minimal interaction with exercise professionals, it is clear that either approach to increasing physical functioning (ie, IND or ICC) was successful in improving physical functioning. In the general population, improving fitness in the least fit people reduces all-cause mortality and specifically mortality caused by cardiovascular diseases.32 Likewise, the US Surgeon General’s report, Physical Activity and Health,1 states that increased physical activity is beneficial in reducing cardiovascular risk, hypertension, muscle and/or joint problems, and disability in the elderly and improving psychological functioning and health-related quality of life. Careful study of the effects of exercise training in dialysis patients on these specific concerns is certainly warranted; however, the REXDP showed that most patients are able to improve physical functioning through increased physical activity participation. Walking and standing up from a seated position are both considered basic actions necessary to perform ADLs and more complex activities.14 Inability to perform these basic actions may severely impact on independence and quality of life.14,15 In older individuals, measures of lower extremity function, including gait speed, are highly predictive of subsequent disability in performing ADLs,16 nursing home admissions, and mortality.14 The sit-to-stand-to-sit test results at baseline in our patients, which were only 15% of normal age-predicted levels, clearly indicate severe limitation in muscle strength. Likewise, the normal gait speed of our patients was much less than normal age values (66% of age norms). Improvements in both of these may contribute, over time, to the patients’ ability to maintain independence and possibly improve overall outcomes. The magnitude of improvement in the intervention group on the physical function tests was not large; however, the difference observed was more than that for the nonintervention patients. The patients on this study had a significant number of comorbidities, were older, and had been on dialysis therapy an average of 35 months, all of which may limit the magnitude of improvement resulting from a low-intensity intervention such as incorporated here. However, our results may help in defining the goals of physical activity interventions. In many of our patients, the goal
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may be prevention of deterioration in functioning over time. Obviously, whatever can be done to prevent the initial deterioration that occurs upon diagnosis of renal failure and initiation of dialysis would be an ideal focus; however, for patients already on dialysis, it is clear that the steady deterioration may be attenuated or prevented and physical functioning maintained with exercise counseling and encouragement. The results of the SF-36 questionnaires clearly indicate that the physical activity was specific in affecting the physical aspects of health-related quality of life because there were no changes in the mental health scores in either group of patients. The scores of our control subjects suggest that the trajectory for the physical dimension scores, such as the physical performance test scores, is deterioration over time. The improvement in the intervention group on the PF and RP scale scores and maintenance in VT, GH, and BP scale scores all suggest benefit from the intervention. The differences between the groups observed on the physical scales were impressive, considering that the nonintervention comparison group was relatively small. The improvement in the PCS is especially important because this scale is highly predictive of overall outcomes in dialysis patients.12,13 DeOreo12 reported that for every increase in PCS score of 5 points, there is an approximately 10% increase in the probability of survival. The intervention group averaged a 4-point increase in the PCS, and the nonintervention group averaged a 6-point decrease in the score. Whether changes in the physical scales on the SF-36 resulting from exercise intervention ultimately result in improved outcomes cannot be determined from this study. However, that physical functioning is not routinely assessed and physical activity is not routinely encouraged as a part of the care of dialysis patients remains of concern and may contribute to poor outcomes. We had a large number of missing tests. The reasons for subjects not performing the various tests are important in determining the best way to measure physical functioning. Many of the tests were missed because of general medical concerns that consisted mostly of ‘‘not feeling well.’’ We believe that if the testing was part of the routine assessment and ordered by the physician (as opposed to being part of a research study),
there would be fewer missed tests caused by vague reasons of malaise. For patients with orthopedic or medical limitations to the physical function testing, the self-reported assessment of physical functioning may be the most informative and effective way to measure changes over time. The number of patients who completed all questionnaires was much higher than the number who completed the physical functioning tests (75% versus 51%). Self-reported physical functioning assessed by questionnaire provides different information from that obtained from physical function tests,14,15 and we do not believe the questionnaire data serve as a surrogate measure for the physical functioning. However, it may often be more practical to assess functioning using questionnaires. Because the improvements observed on the questionnaire were only in the physical domains, and the patterns of change were similar to the measured performance tests, it is likely that this questionnaire tracks changes resulting from increases in physical activity. Most dialysis units have not made the decision to incorporate an exercise professional as a part of the patient care team. The results of the renal exercise demonstration project show that specific individualized prescriptions and encouragement from the dialysis staff can result in significant improvements in physical functioning, measured by both performance-based testing and self-report questionnaires. Although greater gains may be realized with regular and more intensive interaction with an exercise professional, individualized counseling on how to start an exercise program based on available resources at home and individual ability will result in increased physical activity levels in most patients. Incorporation of such counseling as a part of routine care not only fulfills the recommendations of the US Surgeon General of increased levels of physical activity for all Americans, but also increases both objective and self-reported measures of physical functioning and has the potential to improve outcomes in dialysis patients. REFERENCES 1. Office of the US Surgeon General: Physical Activity and Health: A Report of the Surgeon General. Rockville, MD, US Department of Health and Human Services, Public Health Service, 1996 2. Goldberg AP, Geltman EM, Hagberg JM, Delmez JA, Haynes ME, Harter HR: Therapeutic benefits of exercise
training for hemodialysis patients. Kidney Int 16:S303S309, 1983 (suppl) 3. Lundin AP, Stein RA, Frank F: Cardiovascular status in long-term hemodialysis patients: An exercise and echocardiographic study. Nephron 28:234-238, 1981 4. Painter PL, Messer-Rehak D, Hanson P, Zimmerman S, Glass NR: Exercise capacity in hemodialysis, CAPD and renal transplant patients. Nephron 42:47-51, 1986 5. Painter PL, Nelson-Worel JN, Hill MM, Thornbery DB, Shelp WR, Harrington AR, Weinstein AB: Effects of exercise training during hemodialysis. Nephron 43:87-92, 1986 6. Painter PL, Moore GEM: The impact of rHu erythropoietin on exercise capacity in hemodialysis patients. Adv Ren Replace Ther 1:55-65, 1994 7. Painter P: Exercise in end-stage renal disease. Exerc Sports Sci Rev 16:305-339, 1988 8. Robertson HT, Haley NR, Guthrie M: Recombinant erythropoietin improves exercise capacity in anemic hemodialysis patients. Am J Kidney Dis 15:325-332, 1990 9. Shalom R, Blumenthal JA, Williams RS: Feasibility and benefits of exercise training in patients on maintenance dialysis. Kidney Int 25:958-963, 1984 10. Zabetakis PM, Gleim GW, Pasternak FL, Saraniti A, Nicholas JA, Michelis MF: Long-duration submaximal exercise conditioning in hemodialysis patients. Clin Nephrol 8:17-22, 1982 11. Curtin RB, Lowrie EG, DeOreo PB: Self-reported functional status: An important predictor of health outcomes among end-stage renal disease patients. Adv Ren Replace Ther 6:133-140, 1999 12. DeOreo PB: Hemodialysis patient-assessed functional health status predicts continued survival, hospitalization and dialysis-attendance compliance. Am J Kidney Dis 30:204-212, 1997 13. Lowrie EG, Zhang H, LePaine N, Lew NL, Lazarus JM: Health-related quality of life (QoL) among dialysis patients: Associations with contemporaneous measures and future mortality. J Am Soc Nephrol 9:219A, 1998 (abstr) 14. Painter PL, Stewart AL, Carey S: Physical functioning: Definitions, measurement, and expectations. Adv Ren Replace Ther 6:110-123, 1999 15. Guralnik JM, Simonsick EM, Ferrucci L, Glynn RJ, Berkman LF, Blazer DG, Scherr PA, Wallace RB: A short physical performance battery assessing lower extremity function: Association with self-reported disability and prediction of mortality and nursing home admission. J Gerontol 49:M85M94, 1994 16. Guralnik J, Ferrucci L, Simonsick EM, Salive ME, Wallace RB: Lower-extremity function in persons over the age of 70 as a predictor of subsequent disability. New Engl J Med 43:845-854, 1995
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17. Painter P, Blagg C, Moore GE: Exercise for the Dialysis Patient: A Comprehensive Program. Madison, WI, Medical Education Institute, 1995 18. Bohannon RW: Comfortable and maximum walking speed of adults aged 20-79 years: Reference values and determinants. Age Ageing 26:15-19, 1997 19. Bohannon RW: Sit-to-stand test for measuring performance of lower extremity muscles. Percept Mot Skills 80:163-166, 1995 20. Csuka M, McCarty DJ: Simple method for measurement of lower extremity muscle strength. Am J Med 78:7781, 1985 21. Rejeski WJ, Ettinger WH, Schumaker S, James P, Burns R, Elam JT: Assessing performance-related disability in patients with knee osteoarthritis. Osteoarthritis Cartilage 3:1-11, 1995 22. Guyatt GH, Sullivan MJ, Thompson PJ, Fallen EL, Pubsley SO, Taylor DW, Berman LB: The 6- minute walk: A new measure of exercise capacity in patients with chronic heart failure. Can Med Assoc J 132:919-923, 1985 23. Fitts SS, Guthrie MR: Six-minute walk by people with chronic renal failure: Assessment of effort by perceived exertion. Am J Phys Med Rehab 74:54-58, 1995 24. Gunnarsson OT, Judge JO, Earles DR, Marcella GR: A comparison of walking programs for older adults: Effects on six-minute walking distance. Gerontologist 37:126-130, 1997 25. Cahalin LP, Mathier MA, Semigran MJ, Dec GW, DiSalvo TG: The six-minute walk test predicts peak oxygen uptake and survival in patients with advanced heart failure. Chest 110:325-332, 1996 26. Lipkin DP, Scriven AJ, Crake T, Poole-Wilson PA: Six-minute walking test for assessing exercise capacity in chronic heart failure. BMJ 292:653-655, 1986 27. Peters P, Mets T: The 6-minute walk as an appropriate exercise test in elderly patients with chronic heart failure. J Gerontol Med Sci 51A:M147-M151, 1996 28. Ware JE, Sherbourne CD: The MOS 36-Item ShortForm Health Survey (SF-36): I. Conceptual framework and item selection. Med Care 30:473-483, 1992 29. Ware J: SF-36 Health Survey: Manual and Interpretation Guide. Boston, MA, Health Institute, 1993 30. Ware JE, Kosinski M, Keller SD: SF-36 Physical and Mental Health Summary Scales: A User’s Manual (ed 2). Boston, MA, Health Institute, 1994 31. US Renal Data System: USRDS 1991 Annual Data Report. National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 1991 32. Blair SN, Kohl HW, Paffenbarger RS, Clark DG, Cooper KH, Gibbons LW: Physical fitness and all-cause mortality: A prospective study in healthy men and women. JAMA 262:2395-2401, 1989