H/A: Dietary Intake (2007)
To investigate whether closer adherence to a Mediterranean dietary pattern might be related to metabolic aspects of the HAART-induced metabolic syndrome in HIV-positive patients.
- HIV-infected patients
- Aged at least 16 years
- At least six months of cumulative exposure to any anti-retroviral regimen.
None specifically mentioned.
Recruitment
Consecutively enrolled patients were evaluated during a single outpatient visit to the General Clinical Research Center of Beth Israel Deaconess Medical Center; the study sample constituted approximately 10% of the entire population admitted at two ambulatory care clinics and was representative of the clinic population.
Design
Cross-sectional study
Blinding used (if applicable)
Not applicable
Intervention (if applicable)
Not applicable
Statistical Analysis
- Kruskal-Wallis tests followed by post hoc Mann-Whitney analyses were used for comparisons of continuous variables among the four subgroups
- Associations between MedDietScore and aspects of HAART-induced metabolic syndrome were investigated using bivariate analysis and multivariate linear regression
- Variables that were not normally distributed were logarithmically transformed.
Timing of Measurements
Evaluated during single outpatient visit
Dependent Variables
- Body composition assessed through dual-energy X-ray absorptiometry, computed tomographic findings, anthropometrics and data from interviews and questionnaires
- Anthropometrics included: Weight, height and waist and hip circumferences
- Blood drawn for analysis of insulin, glucose and serum lipids.
Independent Variables
- Usual dietary intake was evaluated through the use of a validated self-administered food frequency questionnaire
- Physical activity habits was evaluated through three multiple-choice questions on an exercise questionnaire
- Mediterranean Diet Score (MedDietScore) was calculated.
Control Variables
- Age
- Sex
- Energy intake
- BMI
- Waist to hip ratio
- Smoking
- Exercise habits
- CD4 cell count
- Total PI use
- Total NRTI use
- Total NNRTI use
- Duration of illness.
Initial N
227 patients
Attrition (final N)
227 patients
- 85 did not have fat redistribution, mean age 42±8 years, 10.6% female, 71.4% white
- 42 had fat accumulation, mean age 45±7 years, 28.6% female, 54.8% white
- 56 had mixed fat redistribution, mean age 46±9 years, 17.9% female, 91.1% white
- 35 had fat wasting, mean age 45±7 years, 2.9% female, 88.6% white.
Age
As above
Ethnicity
As above
Other relevant demographics
Anthropometrics
- 85 did not have fat redistribution, mean CD4 count equals 484±281 cells/mm3, mean viral load equals 6,551±20,377 copies per mL
- 42 had fat accumulation, mean CD4 count equals 568±350 cells/mm3, mean viral load equals 10,162±24,710 copies per mL
- 56 had mixed fat redistribution, mean CD4 count equals 506±315 cells/mm3, mean viral load equals 15,792±48,096 copies per mL
- 35 had fat wasting, mean CD4 count equals 502±263 cells/mm3, mean viral load equals 33,881±104,306 copies per mL.
Location
Boston, Massachusetts
Key Findings
- Significant body composition differences were found among groups, with the fat accumulation group exhibiting significantly higher BMI, percentage of body fat, and waist-to hip-ratio compared with the non-fat-redistribution group
- Fasting insulin levels and the HOMA-IR index were significantly higher in the fat accumulation and mixed fat redistribution compared with the non-fat redistribution group, whereas HDL-cholesterol levels were lower in the mixed fat redistribution and the fat wasting groups compared with the non-fat-redistribution and fat accumulation groups
- In the entire study sample, a weak inverse association was found between insulin resistance, estimated using the homeostasis model assessment, and MedDietScore (standardized β= -0.15, P=0.03)
- Interaction models revealed that this was largely driven by an inverse association in patients with fat redistribution (standardized β= -0.13, P=0.02)
- Moreover, MedDietScore was positively correlated with HDL-cholesterol (standardized β=0.15, P=0.01) and marginally negatively associated with circulating triglyceride levels (standardized β= -0.16, P=0.13) in this group of patients.
In conclusion, this is the first study revealing that adherence to the Mediterranean diet is favorably related to cardiovascular risk factors in a sample of HIV-positive patients with the HAART-induced metabolic syndrome studied cross-sectionally. The patients who benefited the most by higher adherence to this dietary pattern were found to be those with fat redistribution. As the Mediterranean diet has proven to be a metabolically favorable dietary pattern in the long term, its adoption may play a role in the prevention and treatment of the HAART-induced metabolic syndrome. Further clinical trials to confirm these findings and to investigate the mechanisms underlying its protective effects are needed.
Government: | NIH | ||
Industry: |
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Not-for-profit |
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Other: | BIDMC |
All subjects from one medical center. Authors note the following limitations:
- Cross-sectional, observational design; interventions based on diet should be considered in the context of other therapeutic approaches for the metabolic syndrome, such as lipid-lowering agents, exercise and drug switching
- Components of the MedDietScore are equally weighted and similarly scored from one to five, which may affect its accuracy
- Insulin resistance was assessed using HOMA and not the euglycemic-hyperinsulinemic clamp, which is the criterion standard method.
Quality Criteria Checklist: Primary Research
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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) | N/A | |
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) | N/A | |
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? | ??? | |
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? | ??? | |
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? | ??? | |
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? | Yes | |
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? | Yes | |
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.) | Yes | |
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? | 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.) | Yes | |
5.3. | In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? | Yes | |
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? | N/A | |
6.2. | In observational study, were interventions, study settings, and clinicians/provider described? | Yes | |
6.3. | Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? | N/A | |
6.4. | Was the amount of exposure and, if relevant, subject/patient compliance measured? | N/A | |
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? | ??? | |
7.1. | Were primary and secondary endpoints described and relevant to the question? | N/A | |
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? | N/A | |
7.4. | Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? | ??? | |
7.5. | Was the measurement of effect at an appropriate level of precision? | ??? | |
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)? | N/A | |
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? | 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? | 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 | |