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To examine the effects of exercise training on cardiovascular risk profile by using traditional CHD risk factors in renal transplant recipients for 12 months.

Renal transplant recipients within one month after kidney transplantation.

• Transplant rejection
• Psychiatric or neurological disorder
• Orthopedic limitations
• Lack of availability for regular follow-up
• Any absolute contraindications to exercise testing or any medical complications that would prevent regular participation.

Recruitment

• Recruitment took place from January 1994 through November 1995
• 96 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
• Cardiovascular risk assessment was measured at baseline and at 12 months after renal transplantation
• All patients in the exercise group were contacted by phone follow-up every other week
• Exercise logs were returned every two weeks to the staff
• The non-exercise group did not receive any specific information on exercise and did not maintain exercise logs.

Blinding Used

Not used; lab tests.

Intervention 

• Exercise training (individualized prescription): Cardiovascular exercise, including primarily walking or cycling for at least 30 minutes per session four times per week
• Control exercise: No training.

Statistical Analysis

• Repeated-measures analysis of variance with one within-subject factor (time, baseline to 12 months) and one between-subject factor (group, exercise or non-exercise) was used to determine differences in changes in absolute values of risk factors over time between the two groups
• All analysis was performed using an intent-to-treat design
• McNemar's test of correlated proportions or chi-square testing was used to determine the differences in the percentage of subjects in each risk factor and the percentage of subjects who changed from high risk to very high risk categories
• Regression analysis was performed to determine the contribution to CHD risk by risk factors such as exercise capacity and BMI.

Timing of Measurements

Ten-years' coronary heart disease (CHD) risk, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), TC-to-HDL-C ratio, systolic and diastolic blood pressure, BMI and exercise capacity were measured at baseline and after 12 months.

Dependent Variables

• Prediction of CHD risk: Performed using the risk-factor categories reported by Wilson et al
• Total cholesterol: Determined from routine laboratory measures
• HDL-C: Calculated from total cholesterol
• Blood pressure
• TC/HDL-C ratio
• BMI: Described by William Haskell at the Stanford Center for Research in Disease Prevention
• Exercise capacity: Measured by maximal metabolic units (METs).

Independent Variables

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

Control Variables

• Age
• Sex
• Smoke
• Prednisone
• Tacrolimus
• Lipid-lowering medications
• Blood pressure medications.

• Initial N: 96
• Attrition (final N): 96; 51 (29 M and 22 F) in the exercise group and 45 (31 M and 14 F) in the non-exercise group.
• Age: Mean 39.7(exercise) and 43.7 (non-exercise)
• Ethnicity: Not mentioned.

Other Relevant Demographics

• Diabetes was the cause of renal failure in 12% of the exercise group and 20% of the non-exercise group
• Only one subject in each group had a history of cardiac disease
• None had symptoms of CHD or electrocardiogram evidence of ischemia on the baseline exercise test
• There were two smokers (4%) in the exercise group and four smokers (9%) in the non-exercise group.

Anthropometrics

Groups were matched at baseline for age, body weight and biochemical variables.

Location

University of California at San Francisco.

 

Overall 10-Year CHD Risk

• There was no change between groups or over time
• Average 10-year risk was 6.2%±5.9% in the exercise group and 9.6%±8.3% in the non-exercise group, compared to the expected 6%.

Cardiovascular Risk Factors Changed During the Intervention

• Total cholesterol and HDL-C were significantly increased over time in all patients; P<0.0001, however there was no difference between the groups although HDL-C level showed a trend to increase in the exercise group, compared to the non-exercise group over time
• TC-to-HDL-C ratio did not change
• BMI increased significantly in all patients over the time; P<0.001, without any difference between groups over time.

Variable	Exercise						Non-Exercise
	Baseline					12 Months	Baseline	12 Months
Total Cholesterol (mg/dL)	201.9±60.6					230.5±64.4	199.6±56.1	227.9±53.3
HDL-C (mg/dL)	41.6±14.4					49.5±16.1	43.0±14.5	46.4±14.2
TC/HDL-C Ratio	5.15±1.79					5.03±1.90	5.10±2.10	5.34±1.97
BMI	24.9±4.6					27.8±7.4	25.1±4.8	27.1±6.2

Values are means±SD.

Systolic and Diastolic Blood Pressure

There were no significant differences over time or between groups.

Exercise Capacity

• There was a significant increase in all patients over the time (P<0.001) and between the two groups (P<0.002)
• The exercise group had the greatest increase.

Other Findings

• Cardiovascular risk-factor categories
  • There was an increase in the percentage of patients in the high- to very-high-risk category for total cholesterol and BMI (23% vs. 39%, exercise; 22% vs. 35%, non-exercise) from baseline to 12 months, respectively; P<0.001
  • The percentage of patients decreased statisticaly in the risk category of HDL-C level (63% vs. 25%, exercise; 63% vs. 27%, non-exercise) from baseline to 12 months in both groups, respectively; P<0.001
  • However, the TC/HDL-C ratio in the exercise group had a greater percentage of patients changing from high- to low-risk category from baseline to 12 months; P<0.009
  • Fitness level was low and remained in the high- to very-high-risk category for most patients (76% in both groups), even though after 12 months the exercise capacity increased significantly in the exercise group, compared to the non-exercise group.
• There was a significant negative relationship between exercise capacity (METs) and CHD risk score (P<0.0001) but the relationship with BMI was not significant
• Prednisone dose was reduced from an average of 24.3mg to 7.6mg per day from baseline to 12 months in both groups. Numbers of blood pressure and lipid-lowering medications administered were not different between the groups during all the study.
• Creatinine serum was not different between the two groups at baseline and after 12 months.

• Exercise training alone does not reduce CHD risk during the first year after transplantation
• Research is needed to study the effects of multiple risk interventions on cardiovascular risks to develop effective interventions and realistics expectations after renal transplantation.

Government:

NIH

• The major limitations of this study were the lack of supervision with the exercise group (although the patients were followed-up by phone and logs every other week) and the absence of a sham training exercise with a follow-up
• The prediction equations used to evaluate the 10-year CHD risk were based on Framingham study and used in populations with mild abnormalities. It might be less valid in predicting CHD risk in the population studied, once they have a high prevalence of cardiovascular risk factors not accounted for in the Framingham risk calculations.
• Sample population in this study seems to be the same as in a study published before (in 2002) by the same authors (recruitment was done at the same period), except during the time of inclusion, patients were enrolled within one month after the transplantation in this study.