EAL

CKD: Physical Activity (2008)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To study the impact of exercise training on health-related finess and quality of life in renal transplant recipients for 12 months.

Inclusion Criteria:

Renal transplant recipients within two months after kidney transplantation.

Exclusion Criteria:

Transplant rejection
Psychiatric or neurologic disorder
Orthopedic limitations
Unavailability for regular follow-up
Any contraindications to exercise test or medical complications that would prevent regular participation
Excluded from the analyses; Patients dropping out during the study due to:
- Disinterest, 19
- Lost to follow-up, 30
- Transplant rejection, two
- Cardiovascular concerns, one
- Orthopedic limitations, 14
- Death, one
- Other reasons, two.

Description of Study Protocol:

Recruitment

Recruitment took place from January 1994 through November 1995
167 clinical patients were recruited after kidney transplantation by the study staff.

Design

Randomized clinical trial for 12 months
Patients were randomized after baseline testing into two groups: Home-based exercise intervention and non-exercise intervention
All health-related fitness parameters and the health-related quality of life questionnaire were assessed at baseline, six months and 12 months after renal transplantation
All patients in the exercise group were initially contacted weekly, then every other week and finally by phone
Exercise logs were returned every two weeks to the staff.

Blinding Used

Not used; lab tests.

Intervention

Exercise training (individualized prescription): Cardiovascular exercise, including primarily walking or cycling for at least 30 minutes four times per week, with a maximal heart rate of 75% to 89% after two weeks from the beginning of the program
Control exercise: No training
All patients participated in an inpatient program of flexibility and strengthening and received a program of cardiovascular exercise to follow at home on discharge.

Statistical Analysis

Repeated analysis of variance with one within-subjects factor (three time-points) and one between-subject factor (exercise vs. non-exercise) was used to determine differences between the two groups as a function of time
All analysis was performed using an intent-to-treat design
Pearson correlations were used to determine associations between variables of interest at the 12-month time-point
Statistical significance was considered when P<0.05.

Data Collection Summary:

Timing of Measurements

Cardiorespiratory fitness, functional and nutritional parameters, biochemical and medications dose were measured at baseline, at six and 12 months
Health-related quality of life assessed at baseline and after 12 months.

Dependent Variables

Peak VO₂(ml per kg per minute): Determined by an open-circuit spirometry system
Percentage age-predicted VO₂: Determined using formulas for sedentary normal individuals
Respiratory exchange ratio and ratings of perceived exertion
Quadriceps muscle strength: Measured by a computerized isokinetic muscle function testing system
Body composition: Determined by dual-energy X-ray absoptiometry
Health-related quality of life: Measured by outcomes short form (SF-36) questionnaire
Body weight (kg) and BMI
Blood samples analysed for creatinine, BUN, hematocrit and hemoglobin.

Independent Variables

Home-based exercise training vs. control non-exercise.

Control Variables

Age
Angiotensin-converting enzyme inhibitors
Calcium-channel blockers
Diuretics.

Description of Actual Data Sample:

Initial N

167.

Attrition (Final N)

97: 60 male, 37 female
Exercise Group: 54
Control Group: 43.

Mean Age

Exercise Group: 39.7
Control Group: 43.

Ethnicity

Caucasian
Hispanic
African-American
Asian
Other.

Other Relevant Demographics

Cause of renal failure
Enrolled patients with glomerulonephritis, hypertension, diabetes mellitus, lupus, PCKD, IGA nephropathy.

Anthropometrics

Groups were matched at baseline for age, body weight and biochemical variables
Mean creatinine was 1.7mg and 1.6mg per dL at baseline for the exercise and control groups, respectively
Location: University of California at San Francisco.

Summary of Results:

Exercise Testing

Physiologic responses at peak exercise and muscle functioning: Respiratory exchange ratio and ratings of perceived exertion were the same in both groups, indicating that the two groups achieved similar levels of exertion at each testing time
The peak VO₂ and the percentage of age-predicted peak VO₂ increased over the time in the exercise group and it was significantly different between groups (P=0.001)
There was a trend in the non-exercise group to increase at baseline to six months, but not at 12 months.

Muscle Strength

There is an increase in the quadriceps muscle strength over time in both groups, but at the end of 12 months the exercise group had significantly greater muscle strength, compared to the non-exercise group (P=0.003).

Variable

Baseline

6 Months

12 Months

Exercise

Non-Exercise

Exercise

Non-Exercise

Exercise

Non-Exercise

Peak Torque (ft-lbs)

53.6±20.7

51.4±17.7

65.5±27.1

61.2±22.6

70.9±28.3

61.2±23.0

Peak Torque per Body Weight (ft-lbs/kg)

34.5±11.8

33.7±9.5

39.5±15.0

37.2±11.2

42.5±15.1

37.2±11.6

Values are means ±SD.

Body Composition

Both groups increased in weight, BMI, lean body mass, fat mass and body fat percentage over time (P<0.03). However, there was no difference between the two groups at 12 months.

Variable

Baseline

6 Months

12 Months

Exercise

Non-Exercise

Exercise

Non-Exercise

Exercise

Non-Exercise

Weight (kg)

70.0±14.5

71.5±16.6

74.1±18.4

76.5±18.4

78.1±22.0

77.0±20.4

BMI

24.8±4.6

25.1±4.8

26.3±4.9

26.9±5.5

27.7±7.4

27.1±6.1

Lean Body Bass (kg)

49.2±11.3

50.1±11.1

49.7±11.6

51.8±11.2

49.7±11.8

51.8±11.6

Fat Mass

20.78±7.1

21.2±9.2

25.1±9.5

26.2±10.4

25.8±10.8

27.6±10.5

Body Fat Percentage

28.7±8.6

27.8±7.1

32.0±9.9

31.7±7.9

32.3±11.2

32.9±8.4

Values are means ±SD.

Other Findings

Health-related quality of life: The only difference between the two groups, according to the SF-36 questionnaire, was the physical function scale, which scored higher for the exercise group after 12 months. At 12 months, both groups were simlar to the general population scores for mental health and the mental composite scale, including the following components: Role limitations owing to emotional health, mental health, general health, vitality and social functioning.
The doses of immunosuppression drugs decreased significantly with time in both groups
There was no difference in creatinine (mean 1.7mg and 1.6mg per dL at baseline for exercise and control group, respectively) and blood urea nitrogen, but hemoglobin and hematocrit were greater increased in the exercise group during the 12 months (P<0.04)
After 12 months, peak VO₂ was significantlty correlated to age, hematocrit, BMI, fat mass and total fat percentage as well as with several physical scales on the SF-36 questionnaire (P<0.05).

Author Conclusion:

Exercise training after two months of transplatation improved cardiorespiratory fitness, increased muscle strength and decreased limitation in physical functioning. However, it did not affect body composition
Exercise recommendations and encouragement should be a part of the routine medical treatment plan for patients after transplant. This can optimize physical functioning and may positively impact overall health with possible improvement of the transplant outcomes.

Funding Source:

University/Hospital:

University of California SF

Reviewer Comments:

In general, the study was well designed, but the major limitation was the lack of supervision with the exercise group, even though the patients were contacted by phone every other week
Another limitation of the study was the lack of sham training exercise and follow-up with those patients
More patients in the control group dropped out, due to medical concerns, than the patients in the exercise group
Only 58% of the original cohort remained in the study. This could result in "healthy cohort effect."
Exercise alone is suggestive of improvement in physical functioning but not in body composition, as raised by the authors
Intervention with supervised training exercise should be investigated to confirm the findings of this study
The population recruited in this study was also used in a second study, published in 2003.

Quality Criteria Checklist: Primary Research
Relevance Questions
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	Yes
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
2.	Was the selection of study subjects/patients free from bias?		Yes
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	Yes
3.	Were study groups comparable?		No
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	???
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	???
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	Yes
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	N/A
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	N/A
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	N/A
4.	Was method of handling withdrawals described?		No
	4.1.	Were follow-up methods described and the same for all groups?	Yes
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	No
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	No
	4.4.	Were reasons for withdrawals similar across groups?	No
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	N/A
5.	Was blinding used to prevent introduction of bias?		No
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	No
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	Yes
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	N/A
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	N/A
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	N/A
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		Yes
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	Yes
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	N/A
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	Yes
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	Yes
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	Yes
	6.6.	Were extra or unplanned treatments described?	Yes
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	Yes
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	N/A
7.	Were outcomes clearly defined and the measurements valid and reliable?		Yes
	7.1.	Were primary and secondary endpoints described and relevant to the question?	Yes
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	Yes
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	Yes
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	Yes
	7.5.	Was the measurement of effect at an appropriate level of precision?	Yes
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	Yes
	7.7.	Were the measurements conducted consistently across groups?	Yes
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		Yes
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	Yes
	8.2.	Were correct statistical tests used and assumptions of test not violated?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	Yes
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	Yes
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	Yes
	8.6.	Was clinical significance as well as statistical significance reported?	Yes
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	N/A
9.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	Yes
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes