H/A: MNT (2009)

Citation:
 
Study Design:
Class:
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Quality Rating:
Research Purpose:

The purpose of this study was to evaluate the effect of a six-month comprehensive lifestyle modification program, modeled after the Diabetes Prevention Program, in HIV-infected patients with the metabolic syndrome.

Inclusion Criteria:
  • Previously documented HIV infection
  • Age 18 years to 65 years
  • Receiving stable combination antiretroviral therapy for more than one month
  • Demonstration of NCEP Adult Treatment Panel III metabolic syndrome, as defined by having at least three of five of the following:
    • Waist circumference more than 102cm in men and 88cm in women
    • Triglyceride levels of 150mg/dL or more or current lipid-lowering drug treatment
    • High-density lipoprotein (HDL)-cholesterol less than 40mg/dL in men and 50mg/dL in women
    • Blood pressure 130mmHg/85mmHg or more or current antihypertensive drug treatment
    • Fasting glucose level of 110mg/dL or more.

 

Exclusion Criteria:
  • Any new serious opportunistic infection within the past six weeks
  • History of unstable angina
  • Aortic stenosis
  • Uncontrolled hypertension or other contraindication to increase physical activity
  • Current therapy with insulin or other diabetic agent, or fasting blood sugar more than 126mg/dL
  • Alanine aminotransferase levels more than five times the upper limit of normal
  • Creatinine more than 2.0mg/dL
  • Required parenteral nutrition or glucocorticoid therapy, estrogen, progestational derivative or ketoconazole use within three months of the study
  • Current substance abuse
  • Hemoglobin less than 10mg/dL
  • Pregnant or actively seeking pregnancy
  • Breastfeeding
  • Using supraphysiological doses of testosterone or physiological testosterone replacement for fewer than three months.
Description of Study Protocol:

Recruitment

Subjects were recruited through HIV clinics and providers in the Boston area, HIV community service programs as well as advertisements in the greater Boston region. Subjects responding to community announcements or referred by HIV providers were screened by telephone to determine potential eligibility. Appropriate candidates for the study were then scheduled for a formal outpatient screening visit to determine eligibility.

Design

After baseline assessment, subjects were randomly assigned to a lifestyle modification group or control group (no lifestyle modification), stratified by fasting blood sugar (≤110mg/dL or ≥110mg/dL).

Testing included determination of fasting lipids, glucose, hemoglobin A1C,  hemoglobin, alanine aminotransferase, creatinine as well as the CD4 cell count and HIV viral load. Insulin levels were also measured and a Homeostasis Model Assessment of insulin resistance was calculated. Weight, height, iliac waist and hip circumference and resting blood pressure were measured. Lipodystrophy scores were calculated based on an evaluation of face, neck/shoulders, arms, abdomen and hips/legs, with graded values between zero and two for fat loss and accumulation. Identical assessments were done at the six-month visit.

In addition to the baseline and six-month assessments, subjects completed a brief safety visit three months after randomization. Subjects were evaluated for any potential adverse effects of the lifestyle modification program.

Blinding used

None.

Intervention

The lifestyle modification group attended weekly one-on-one counseling sessions for six months, covering a core curriculum modeled after the Diabetes Prevention Program study 16-week core curriculum intervention. The initial core curriculum sessions were completed within the first 18 weeks with weekly sessions by the dietitian staff at the Massachusetts General Hospital Clinical Research Center. Each session was recapped in the first 12 to 15 minutes of the following session, and the entire core curriculum was repeated for reinforcement between weeks 19 and 24 of the study. Registered dietitians were trained in research methodologies, including motivational interviewing and behavioral modification. The control group received a one-time counseling session with the dietitian staff at the baseline visit and monthly phone calls from the study investigator for follow-up throughout the six months of the study. Subjects were permitted to continue baseline levels of regular exercise during the protocol.

Statistical Analysis

A comparison of demographic variables was made at baseline, using Student's T-test for continuous variables and the chi-square test for non-continuous variables. Changes in treatment effects were compared between lifestyle and control groups using Student's T-test. For variables with levels that differed between the groups at baseline, results were confirmed using analysis of covariance (ANCOVA), controlling for baseline values.

 

Data Collection Summary:

Timing of Measurements

Measurements were collected at baseline and six months.

Dependent Variables

  • Body mass index
  • Metabolic syndrome parameters (waist circumference, triglycerides, HDL-cholesterol, fasting glucose, systolic and diastolic blood pressure)
  • Other cardiac risk factors [cholesterol, low-density lipoprotein (LDL)-cholesterol, hemoglobin A1C ]
  • Cardiorespiratory fitness (MAQ, V02max, lipodystrophy score)
  • Immune function (viral load, CD4 cell count).

Independent Variables

Weekly counseling sessions on lifestyle modification.

Control Variables

  • HIV status
  • Metabolic syndrome.

 

Description of Actual Data Sample:

Initial N

34 (16 in lifestyle modification group, 18 in control group).

Attrition (final N)

28 (12 in lifestyle modification group, 16 in control group).

Age

Lifestyle modification group: 45 years±2 years; control 46 years±2 years.

Ethnicity

  • Lifestyle modification group: 19% Caucasian, 69 % African American, 6 % Hispanic, 6% other
  • Control group: 44% Caucasian, 56% African American.

Anthropometrics

  • BMI was 34.6±2.1 (lifestyle modification group) and 30.1±1.2 (control group); P=0.065
  • Waist circumference: 113.7cm±4.1cm (lifestyle modification group), 101.1cm± 2.5cm (control group); P=0.011.

Location

Greater Boston area.

 

Summary of Results:

 Comparison of Baseline and Treatment Effect Between Groups 

  Lifestyle Modification Group  Control Group  
 

Baseline (n=16)

Change at Six Months (n=12) Baseline (n=18) Change at Six Months (n=16) P-value for Change Between Treatment Groups
Waist circumference (cm)

113.7±4.1

-2.6±1.2

101.1±2.5

1.2±1.0 0.022
Systolic blood pressure (mmHg)

138±4

-13± 4 131±4 4±4 0.008
Hemoglobin A1C (%)

5.4±0.1

-0.1±0.1

5.187±0.26

0.2±0.1 0.017
MAQ (MET, hours per week) 33.2±12.1 17.7±14.3 61.3±17.3 -33.1±12.7 0.014
Lipodystrophy score 3.9±0.4 -1.2±0.3 4.1±0.3 0.9±0.6 0.006

Other Findings

Mean percentage of compliance with counseling sessions was 75%.

Subjects in the intervention group demonstrated a reduction in calorie intake and percentage of calories from saturated fat and an increase in total fiber intake.

There were no significant changes in dietary intake in the control group.

Author Conclusion:

These data demonstrate that intensive lifestyle modification significantly improved important cardiovascular risk indices in HIV-infected patients with metabolic syndrome. Lifestyle modification may be a useful strategy to decrease cardiovascular risk in this population.

Funding Source:
Reviewer Comments:

There was a difference in ethnicity of the subjects between the two groups; could that have accounted for the fact that more subjects dropped out of the intervention group than the control group? There were significant differences between the two groups at baseline for BMI and waist circumference, but the researchers used ANCOVA analysis to control for the baseline differences.

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? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  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? 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? N/A
  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.) No
  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? No
  6.6. Were extra or unplanned treatments described? No
  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? ???
  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? Yes
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