EAL

CKD: Physical Activity (2008)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To examine whether exercise acutely improved endothelial-mediated vasodilatation among renal transplant patients
To compare the effect of a three-minute walk on brachial artery endothelial vasodilatation in kidney transplant receipients and health controls.

Inclusion Criteria:

Renal transplant recipients and healthy controls matched by age, race and sex
Subjects were required to be physically inactive and not to have exercised more than 30 minutes three times weekly, in the past 12 weeks.

Exclusion Criteria:

Control subjects with more than one cardiovascular disease (CVD) risk factor or previous history of a CVD event and who were taking any CVD medications, antioxidant agents or immunosuppressants were excluded
Transplant recipients with a fistula in the right arm were excluded, since the brachial ultrasound was performed on the right arm
For both groups, any contraindications to exercise, smoking, hypertension, positive human immunodeficiency virus serology and immunologic conditions that affect endothelial function, such as lupus, rheumatoid arthritis, thyroid disease and diabetes mellitus.

Description of Study Protocol:

Recruitment

Transplant receipients were recruited from the transplant program at Hartford Hospital in Hartford, CT
The controls were recruited from the greater Hartford area.

Design

Non-randomized controlled study.

[Note: For the purpose of CKD project, only the group of renal transplant patients were considered, thus it is considered a before-and-after study.]

Blinding Used

B-mode scans of the right brachial artery were obtained by one experienced technician and analyzed by a different technician who was unaware of each subjects' group assignment and whether the scan was before or after exercise.

Intervention

Treadmill walking: At a rating of perceived exertion of 13, which corresponds to a "somewhat hard effort," for 30 minutes. Heart rate was recorded every five minutes to verify that all subjects were walking at a pace between 70% and 85% of their age-predicted maximal heart rate.

Statistical Analysis

A 2x2x3 (group x occasion x time) mixed-factorial analysis of variance was conducted to analyze the dependent variable, percentage change in brachial artery diameter
The analysis included one independent variable and two repeated-measures factors
The independent variable group had two levels: Post-transplant and controls
The first repeated-measures factor, occasion, also had two levels: Pre- and post-treadmil walk
The second repeated-measures factor, time, included three levels: Percentage change in diameter after one, three and 15 minutes post-occlusion
Tukey post-hoc comparisons were conducted following significant interactions
A level of P<0.05 was considered statistically significant.

Data Collection Summary:

Timing of Measurements

Before and immediately after the 30 minutes of treadmill walk and also at one, three, and 15 minutes during exercise.

Dependent Variables

Endothelial function: High-resolution ultrasound of the brachial artery and ischemic forearm occlusion before and immediately after the 30 minutes of treadmill walk
Arterial cross-sectional diameter was measured from the near endothelial-luminal surface to the distal luminal surface
Endothelial function was quantified as the percentage change in brachial artery diameter (vasodilatation) by dividing the change in diameter by the baseline value.

Independent Variables

Treadmill walk.

Control Variables

None.

Description of Actual Data Sample:

Initial N: 11 renal transplant receipients (eight women and three men) and 11 controls (eight women and three men)
Attrition (final N): 11
Age: 30 to 65 years old
Ethnicity: 73% Caucasian, 18% African-American and 9% Hispanic
Other relevant demographics: Transplant recipients had received their transplant over one year before the study (mean 2.9 years, range 1.0 to 5.6 years).

Anthropometrics

Mean BMI
- Transplant: 29.4
- Control: 24.9
- P=0.05.
Renal transplant recipients had significantly higher Tg levels (86.6mg vs. 79.1mg per dL; P<0.05), however HDL, LDL and CRP values were not significantly different between the groups.

Location

United States.

Summary of Results:

The healthy group experienced a significant increase in vasodilatation after the exercise bout one minute post-occlusion, when compared with the transplant group (22% vs. 3%, P<0.05)
The healthy group had a significant higher vasodilatation from pre- to post-treadmil walk (one minute post-occlusion), when compared with the transplant group (from 3% to 22% vs. 1% to 3%, P<0.05)
Baseline and pre-exercise percentage change of endothelial-mediated vasodilatation were not statistically different within and between groups
Endothelial-mediated vasodilatation at three and 15 minutes post-occlusion before and after exercise were not statistically different within and between groups.

Author Conclusion:

The present study demostrated an increased endothelial-mediated vasodilator response in healthy individuals, but not in renal transplant patients after a signle bout of exercise at a moderate intensity
Further research is required to identify the mediators of this effect and to determine whether the abnormal endothelial-mediated vasodilatory response in the transplant patients can be normalized by aggressive risk factor management or exercise.

Funding Source:

Government:	US Coast Guard
University/Hospital:	University of West Florida, Heartford Hospital, Springfield Hospital

Reviewer Comments:

For the purpose of CKD project, only the group of transplant patients will be included in the overview table. There was no "no exercise" group of renal transplant patients.
Healthy "controls" were not comparable to renal transplant patients
Major limitations: Weak study design, small sample size and acute effect only
Reporting errors between the abstract and methods. In abstract, the authors stated that this study compared the effect of a 30-minute walk, but in the method the outcomes only measured one, three and 15 minutes after exercise. It is unclear whether subjects exercised for 30 minutes or 15 minutes.

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)	???
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	???
	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?		No
	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?	No
	2.2.	Were criteria applied equally to all study groups?	No
	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?	No
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)	No
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	No
	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?		Yes
	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%.)	Yes
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	N/A
	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?		Yes
	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?		No
	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?	No
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	No
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	N/A
	6.6.	Were extra or unplanned treatments described?	N/A
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	N/A
	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?		No
	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?	No
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	No
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	N/A
	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?	No
	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?		No
	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?	No
	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)?	N/A
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	No
	8.6.	Was clinical significance as well as statistical significance reported?	No
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	No
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?	No
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