EAL

H/A: Hyperlipidemia (2009)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To assess the relationships between dietary intake, body composition and metabolic parameters in HIV-infected patients with fat redistribution.

Inclusion Criteria:

Documented HIV infection
Age of 18 to 60 years
Receipt of stable antiviral medication regimen for at least six weeks
Evidence of fat redistribution
Controls had to be free of any significant medical condition, including diabetes, coronary artery disease and renal disease, and to be receiving no medications.

Exclusion Criteria:

History of diabetes mellitus
Receiving concurrent therapy with insulin, antidiabetic agents, glucocorticoids, testosterone, growth hormone, estrogen or anabolic steroids
Current substance abusers
Had a major opportunistic infection within the previous six weeks.

Description of Study Protocol:

Recruitment

HIV-infected men and women with recent complaints of fat redistribution were recruited from 1998 through 1999 from the multidisciplinary HIV practice at the Massachusetts General Hospital, Boston, from community-based practices, and by newspaper advertisement. Matched controls recruited through hospital and local advertisements.

Design

Case-control study.

Statistical Analysis

Student's T-tests used to determine statistically significant differences between groups
Categorical variables compared between groups with a chi-squared statistic
Multivariate regression models used to evaluate relationships between dietary intake and metabolic parameters with adjustment for confounding variables.

Data Collection Summary:

Timing of Measurements

Subjects were studied after an overnight fast.

Dependent Variables

Fasting glucose, insulin, serum lipids measured through biochemical and immunologic assays
Oral glucose tolerance testing: 75g oral glucose challenge, with glucose and insulin determinations at 30, 60, 90 and 120 minutes
Body composition measured through DEXA.

Independent Variables

Dietary history obtained by nutrition staff trained in modified Burke diet history technique
Medical history
Physical examination.

Control Variables

Age
Sex
BMI
Waist-to-hip ratio
Kilocalories
Duration of protease inhibitor use
Fat redistribution pattern
Alcohol intake
Dietary fiber intake
P:S fat ratio.

Description of Actual Data Sample:

Initial N: 85 consecutive HIV-infected patients, 35 matched healthy male controls
Attrition (final N): 85 patients (62 men, 23 women)
Age: Mean age, 43.5±0.9 years
Other relevant demographics: Mean BMI, 26.3±0.5
Anthropometrics: Cases and controls were age- and BMI-matched
Location: Boston, Massachusetts.

Summary of Results:

Relationship of Dietary Intake of Polyunsaturated Fat, Fiber and Alcohol to Insulin and Lipids

Variable	Estimate (95% CI)	P-value
Insulin AUC
Age, years	286 (94 to 478)	0.004
PI therapy duration, months	121 (24 to 219)	0.02
P:S ratio	7,087 (2,581 to 11,592)	0.003
Dietary fiber, g	-289 (-131 to -446)	0.001
LDL cholesterol
Alcohol, g	2.2 (0.8 to 3.7)	0.003
HDL cholesterol
Alcohol, g	0.5 (0.1 to 0.9)	0.01
Female sex	8.3 (2.4 to 14.3)	0.007
BMI	0.9 (0.2 to 1.5)	0.01
WHR	-72 (-22 to 122)	0.005

Other Findings

Only age (P=0.004), protease inhibitor use duration (P=0.02) and P:S fat ratio (P=0.003) were positively associated with insulin area under the curve.

Dietary fiber intake was inversely associated with the insulin area under the curve (P=0.001).

A 5g increase in daily dietary fiber intake was associated with a 14% reduction in insulin area under the curve.

Alcohol consumption was a significant positive predictor of LDL cholesterol (P=0.003), HDL cholesterol levels (P=0.01), as well as BMI (P=0.01) and female sex (P=0.007).

Waist-to-hip ratio was inversely related to HDL concentration (P=0.005).

Cholesterol, LDL and triglyceride levels were higher in subjects with fat redistribution (P=0.01) and in control subjects (P=0.001).

Patients with fat redistribution also had significantly lower HDL cholesterol levels than did control subjects (P=0.001).

Fasting insulin levels were significantly higher in patients with fat redistribution than they were in control subjects (19.5±2.3µU per ml vs. 11.8±1.3µU per ml, P=0.01).

Author Conclusion:

Our data indicate a number of potential targets for dietary modification among patients with HIV infection and fat redistribution. In this regard, prospective dietary intervention studies are necessary to determine whether alteration in polyunsaturated fat intake and increased dietary fiber will be of benefit in treating the insulin resistance associated with HIV-related fat redistribution, and whether reduction of alcohol and cholesterol intake will be beneficial. Further investigation is needed to assess the impact of dietary intake and its modification on metabolic risk factors in HIV-associated fat redistribution.

Funding Source:

Reviewer Comments:

Different numbers of cases and controls; controls were all male. Authors note limitations of prospective dietary food records providing a more accurate assessment than patients' recollections of the preceding month.

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)	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?		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?		???
	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.)	No
	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?	N/A
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	Yes
	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?	N/A
	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?	N/A
	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?		???
	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?	???
	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?	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