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HIV/AIDS

H/A: Monitoring of Food Intake (2009)

Citation:

Hendricks KM, Dong KR, Tang AM, Ding B, Spiegelman D, Woods MN, Wanke CA. High-fiber diet in HIV-positive men is associated with lower risk of developing fat deposition. Am J Clin Nutr, 2003; 78: 790-795.

PubMed ID: 14522738
 
Study Design:
Nested case-control
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
The purposes of this study were to evaluate the dietary intake of patients with HIV infection six to 24 months before they met our definition of fat deposition and to compare the differences in intake between those who had fat deposition and those who did not.
Inclusion Criteria:

Participants enrolled in Nutrition for Healthy Living study, an ongoing longitudinal study examining the nutritional and metabolic consequences of HIV infection.

  • Criteria for NHL study: HIV-positive adults (at least 18 years of age), living in the greater Boston area or in Rhode Island
  • Criteria for the current study: Male with a BMI of 23 to 26.
Exclusion Criteria:

Criteria for NHL study

Excluded if subject had any of following conditions at enrollment: Pregnancy, diabetes, thryoid disease or malignancies other than Kaposi's sarcoma.

Criteria for This Study

  • Cases were excluded if they did not have at least consecutive study visits before their index visit
  • Cases were also excluded if they did not have complete diet records for both of the two visits before the index visit
  • Controls were excluded if they had a mid-upper-arm circumference under 28.7cm, which is equal to or greater than the 10th percentile of men aged 18 years and older and was used to eliminate those with wasting or fat atrophy.
Description of Study Protocol:

Recruitment

  • Participants enrolled in the Nutrition for Healthy Living study, an ongoing longitudinal study examining the nutritional and metabolic consequences of HIV infection
  • Males with BMI of 23 to 26
  • Cases defined as those with fat deposition
  • Controls were defined as those without fat deposition
  • Cases were identified at the visit when they were first recognized as having fat deposition, which was referred to as the "index visit"
  • For each case, the investigators randomly selected one control without fat deposition, matched by age (±5 years), race (African-American or non-African-American), HAART use (ever or never), length of follow-up (±12 months) and CD4 cell count (ever 200 or lower; or always above 200 cells per uL)
  • The control match date was referred to as the "index visit" for the controls.

Design

Nested case-control.

Intervention

None.

Statistical Analysis

  • Dietary intake comparisons between cases and controls were the average intake form two three-day food records, approximately six to 24 months before the index visit
  • Specific macronutrients and micronutrients were compared between cases and controls by using T-tests for normally distributed nutrients and Wilcoxon rank-sum tests for nutrients with skewed distributions
  • Conditional logistic regression analysis was used to estimate the odds ratio of fat deposition associated with each nutrient.
Data Collection Summary:

Timing of Measurements

  • Between 1995 and 1999, participants enrolled in the Nutrition for Healthy Living Study
  • Diet records were analyzed and averaged for the two visits before the index visits of cases and controls.

Dependent Variables

Dietary variables, including:

  • Energy (kcal)
  • Energy by weight (kcal per kg)
  • Total carbohydrate (grams)
  • Total protein (grams)
  • Total fat (grams)
  • Cholesterol (mg)
  • Alcohol (grams)
  • Percentage of calories from carbohydrates
  • Protein
  • Fat
  • Saturated fatty acids
  • Monounsaturated fatty acids
  • Polyunsaturated fatty acids
  • Polyunsaturated-to-saturated ratio
  • N-3 fatty acids (grams)
  • Simple sugars (grams)
  • Starch (grams)
  • Dietary fiber (grams) of total, soluble, insoluble, pectin (grams).

Independent Variables

  • Cases: Participants with fat deposition; fat deposition was defined as a waist-to-hip ratio of over 0.95, which is above the recommended normal range of less than 0.90 for men
  • Controls: Participants without fat deposition, but no fat atrophy.

Control Variables

  • Potential confounders examined included the number of AIDS-defining conditions, whether a person was trying to change his weight (either gain or lose), individual food insecurity, use of protease inhibitors, use of vitamin and mineral supplements, smoking and resistance training
  • Confounders were assessed at the index visit.
Description of Actual Data Sample:

Initial N: 47 cases, 47 controls

Attrition (final N): 47 cases and 47 controls

Age: cases 43.2 ± 5.3; controls 41.9 ± 5.1

Ethnicity: cases 12.8% African American, 2.1% Latino or Hispanic, 83.0% white, 2.1% other; controls 12.8% African American, 4.2% Latino or Hispanic, 76.6% White, 6.4% other

Other relevant demographics:

Anthropometrics

  • BMI (kg/m2): cases 24.7 ± 0.9; controls 24.5 ± 0.8
  • Waist circumference (cm): cases 92.5 ± 4.5; controls 85.6 ± 4.4  (P<0.0001)
  • Hip circumference (cm): cases 94.1 ± 4.1; controls 94.4 ± 3.4
  • Waist-to-hip ratio: cases 0.98 ± 0.03; controls 0.91 ± 0.04 (P<0.0001)
  • Midupper-arm circumference (cm): cases 31.1 ± 2.1; controls 33.1 ± 8.7
  • Subscapular skinfold thickness (mm): cases 18.6 ± 7.6; controls 15.6 ± 5.9 (P=0.03)
  • Triceps skinfold thickness (mm): cases 8.6 ± 5.1; controls 7.5 ± 4.4

Disease Information:

  • CD4 cell count (cells/uL): cases 478 ± 301; controls 377 ± 269
  • viral load (copies/mL): cases 21,506 ± 48,241; controls 31,290 ± 81,933
  • log10 Viral load: cases 3.08 (2.30, 4.24); controls 3.20 (2.30, 4.46)
  • Lowest viral load ever: 200 (200, 1100); controls 200 (200, 3640)
  • Highest viral load ever: 17,369 (2853, 84,808); controls 38,945 (1597, 138,201)

Other information

  • Resting energy expenditure: cases 2055 ± 213; controls 2070 ± 213 

Location:  greater Boston area or Rhode Island

Summary of Results:

 Table Two: Comparison of Dietary Factors Two Visits Before the Index Visit

Variables

Cases

Controls

P-Value
Risk Ratio1

Energy (kcal)

2,771 (2,303, 3,192)

2,898 (2,474, 3,748)

0.15

Energy/weight (kcal/kg)

35 (31, 42) 

40 (34, 49) 

0.03
0.95 (0.91, 0.99)

Total carbohydrate (g)

339 (277, 401) 

372 (303, 462) 

0.39 

Total protein (g) 106 (92, 116) 119(101, 145)

0.01
0.98 (0.96, 0.99)

Total fat (g) 112 (86, 128) 113 (89, 149) 0.42
Cholesterol (mg) 382 (288, 512) 413 (269, 584) 0.84
Alcohol (g) 0.14 (0.04, 7.25) 0.70 (0.04, 6.22) 0.46

Percentage of calories (%)

From carbohydrate

From protein


From fat

From saturated fatty acids

From monounsaturated fatty acids

From polyunsaturated fatty acids

 

 

50 (45, 53)

15 (13, 18)


36 (33, 39)

12 (10, 14)

14 (11, 15)


6.7 (4.7, 8.1)

 

48 (43, 53)

17 (14, 18)

 
35 (32, 40)

12 (10, 14)

13 (12, 15)


6.6 (5.4, 7.5)

 

0.49

0.10
0.87 (0.74, 1.02)

0.69

0.90

0.99


0.78

Polyunsaturated-to-saturated ratio

0.59 (0.42, 0.83)

0.57 (0.42, 0.81)

0.98

n-3 fatty acids (g)

1.84 (1.43, 2.77)

2.07 (1.71, 3.07)

0.10
0.74 (0.52, 1.1)

Simple sugars (g)

167 (116, 216)

164 (106, 237)

0.91

Starch (g)

134 (102, 171)

157 (106, 188)

0.18

Dietary fiber (g)

Total


Soluble


Insoluble

 

19 (14, 24)

7.0 (5.4, 8.6)


11.8 (8.8, 14.5)

 

23 (18, 29)

8.8 (7.0, 11.0)


13.9 (10.7, 18.4)

 

0.01
0.93 (0.88, 0.99)

<0.01
0.79 (0.66, 0.95)

0.03
0.91 (0.84, 0.99)

Pectin (g) 2.1 (1.2, 2.6) 2.6 (1.5, 3.5)

0.02
0.71 (0.50, 0.99)

1Based on conditional logistic regression models with dietary variables as the exposure and case or control status as the outcome. 95% CIs in parentheses.

Other Findings

  • 81% of cases and controls were taking HAART
  • 38% of both groups had CD4 cell counts above 200 cells per uL
  • Hemoglobin was not different between cases and controls
  • Fasting serum triacylglycerol concentrations did not differ significantly between cases and controls (197±169mg per dL for cases and 256±247mg per dL for controls)
  • An increase in the intake of all types of fiber was significantly associated with a decreased risk of development of fat deposition. The magnitude of risk reduction ranged from 2% for each one-gram increase in total protein intake to approximately 30% for each one-gram increase in pectin intake.
  • Potential confounders: Resistance training (weight-bearing exercise) was performed significantly (P=0.05) more often by those without fat deposition than by those with fat deposition. Smoking (currently) occurred significantly (P=0.05) more often in those with fat deposition than in those without fat deposition. Neither resistance training or smoking was associated with any of the dietary intake variables. Therefore, although their inclusion in the multivariate analyses affected the significance of some of the nutrients, it did not substantially change any of the risk estimates for these nutrients. Because of the small sample size and the borderline significance of the two confounding variables, the authors left them out of the final models to increase power.

Results Given in Discussion Section

  • Body fat (kg), as measured by BIA: Cases, 17.65±5.30; controls 15.00±4.86; P=0.01
  • Authors stated there was a lower percentage lean body mass by BIA in the cases, however no data and no P-value are given to support this statement.
Author Conclusion:
  • Study showed that a diet high in fiber may be beneficial in preventing the development of fat deposition in normal-weight HIV-positive persons
  • The importance of overall good nutrition, especially adequate energy and protein intakes, in patients with HIV infection is emphasized by this study
  • The authors suggested that a healthy lifestyle, including diet, resistance training and avoidance of unhealthy habits, such as smoking, may be beneficial in preventing the development of fat deposition
  • These findings call attention to the importance of targeted nutrition education and follow-up and to the need for well-designed nutrition intervention studies, which carefully evalute the efficacy of nutrition therapy in this patient population.
Funding Source:
Government: NIDDK
University/Hospital: Tufts-New England Medical Center GCRC
Reviewer Comments:

Same original study as Dong et al, 2006, limitations as noted by authors:

  • Small number of men, so findings may not be applicable to women
  • Study focused on fat deposition, so findings may not be applicable to fat atrophy or metabolic complications associated with lipodystrophy.
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? ???
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) N/A
  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? 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.) 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? N/A
  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%.) N/A
  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? 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? 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? Yes
  6.6. Were extra or unplanned treatments described? Yes
  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? N/A
  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)? 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