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HIV/AIDS

H/A: Monitoring of Food Intake (2009)

Citation:

Dong KR, Wanke CA, Tang AM, Ding B, Hendricks KM. Dietary glycemic index of human immunodeficiency virus-positive men with and without fat deposition. J Am Diet Assoc. 2006; 106: 728-732.

PubMed ID: 16647332
 
Study Design:
Nested case-control study
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
  • The purpose of this study was to focus on glycemic index and its potential association with development of fat deposition in HIV
  • The authors hypothesized that individuals with HIV who have high glycemic index diets and low dietary fiber intake are more prone to development of fat deposition.
Inclusion Criteria:
  • Participant in Nutrition for Healthy Living Study
  • Male with BMI between 23kg and 26kg per m2.
Exclusion Criteria:
  • Did not have at least two consecutive study visits prior to the "index visit" [Reviewer's note: Visit in which cases were first recognized with fat deposition]
  • If the two prior visits were not between one and two years
  • If they did not have diet records
  • Controls were excluded if they had a mid-arm circumference below 28.7cm, which is at or above the 10th percentile of men 18 years or older, in order to eliminate those with fat atrophy.
Description of Study Protocol:

Recruitment

  • Participants enrolled in Nutrition for Healthy Living Study, an ongoing longitudinal study examining the nutritional and metabolic consequences of HIV infection
  • Males with BMIs between 23kg and 26kg per m2
  • Cases were defined as those with fat deposition
  • Controls were defined as those without fat deposition
  • Cases were identified at the visit they were first recognized with fat deposition, referred to as the "index visit"
  • For each case, the investigators randomly selected one control without fat deposition, matched by age (±5 years), race, highly active anti-retroviral therapy use (ever vs. never), length of followup (±12 months) and CD4 counts (ever, up to 200 cells per uL vs. always, over 200 cells per uL)
  • The control match date was referred to as the "index visit" for controls.

Design

Nested case-control study.

Intervention

None.

Statistical Analysis

  • Fiber was used as primary outcome in detecting sample size. To detect a five-gram difference in total dietary fiber, the investigators calculated that they would need approximately 40 participants in each group, assuming an alpha-level of 0.05, 80% power, using a two-sided T-test.
  • Specific nutrients were compared using T-tests for normally distruted nutrients and Wilcoxon rank-sum tests for nutrients with skewed distributions.
Data Collection Summary:

Timing of Measurements

  • Between 1995 and 1999, participants were enrolled in the Nutrition for Healthy Living study
  • Semi-annual visits.

Dependent Variables

  • Dietary variables including:
    • Energy (kcal)
    • Energy/weight (kcal/kg)
    • Total carbohydrate
    • Percentage calories from carbohydrate
    • Sugars (g)
    • Starch (g)
    • Total dietary fiber (g)
    • Soluble dietary fiber (g)
    • Insoluble dietary fiber (g)
    • Pectin (g)
    • Average glycemic index per meal
    • Average glycemic index per day
    • Differences in glycemic index range within each day
    • Differences in glycemic index range between days
    • Total protein (g)
    • Percentage calories from protein
    • Protein/weight (g/kg)
    • Total fat (g)
    • Cholesterol (mg)
    • Percentage calories from fat
    • Percentage calories from saturated fatty acids
    • Percentage calories from monounsaturated fatty acids
    • Percentage calories from polyunsaturated fatty acids
    • Polyunsaturated to saturated fat ratio
    • N-3 fatty acids (g)
    • Average meal number per day.
  • Three-day food record at each visit
  • A 24-hour recall was obtained when a participant did not have a completed food record
  • Nutrition Data System software (Nutrition Coordinating Center, University of Minnesota) was used to analyze data
  • Foster-Powell's glycemic index tables and unpublished tables from Thomas Wolever, DM, PhD (University of Toronto) were used to supplement missing published glycemic index values
  • The differences in glycemic index within each day was calculated by taking the difference between the highest and the lowest glycemic meal each day
  • The investigators also evaluated within-person variation in glycemic index between days using the two three-day food records. Of the six days, the lowest glycemic index per day was subtracted from the highest glycemic index per day.
  • Glycemic index values under 55 were considered low, those between 55 and 70 were considered moderate and those over 70 were considered high.

Independent Variables

  • Cases: Participants with fat deposition; fat deposition was defined as a waist-to-hip ratio over 0.95, which is classified as central abdominal obesity
  • Controls: Participants without fat deposition, but no fat atrophy.

Control Variables

  • Potential confounders were examined at the index visit
  • Acquired immunodeficiency syndrome-defining conditions
  • Intentional weight change
  • Food insecurity
  • Use of protease inhibitors
  • Vitamin or mineral supplements
  • Smoking
  • Resistance training.
Description of Actual Data Sample:

Initial N

  • 678 participants were enrolled into the Nutrition for Healthy Living Study
  • 37 cases
  • 37 controls.

Attrition (final N)

37 cases and 37 controls

Age
  • Cases: 43.0±5.2 years
  • Controls: 41.9±5.1 years.

Ethnicity

For both cases and controls
  • Non-Hispanic African-American: 13.5%
  • Non-Hispanic white: 83.8%
  • Other: 2.7%.

Anthropometrics 

  • BMI (kg/m2): Cases, 24.6±0.9; controls, 24.5±0.8
  • Waist circumference (cm): Cases, 92.3±4.8; controls, 86.3±4.4 (P<0.0001)
  • Hip circumference (cm): Cases, 93.9±3.6; controls, 94.3±3.6
  • Waist-to-hip ratio: Cases, 0.98±0.03; controls, 0.92±0.04 (P<0.0001)
  • Mid-upper arm circumference (cm): Cases, 31.3±2.1; controls, 33.4±9.8
  • Subscapular skinfold thickness (mm): Cases, 18.7±7.4; controls, 15.3±6.0 (P=0.03)
  • Triceps skinfold thickness (mm): Cases, 8.2±4.8; controls, 6.7±3.3.

Disease and Other Related Information

  • CD4+ counts (cells/uL): Cases, 483.1±277.6; controls, 375.1±285.2
  • Log10 of adjusted viral load [median (25th percentile, 75th percentile)]: Cases, 3.10 (2.30, 4.18); controls, 3.19 (2.30, 4.46)
  • Resting energy expenditure: Cases, 2,080.8±211.5; controls, 2,118.8±192.6
  • Smoking: Cases, 40.6%; controls, 18.2% (P=0.05)
  • Resistance training: Cases, 33.3%; controls, 44.1%.

Location

Not stated.

Summary of Results:

Table Two: Comparison of Dietary Factors in Nutrition for Healthy Living Participants with Fat Deposition (Cases) and Without Fat Deposition (Controls) Six to 24 Months Prior to the Index Visit (Median, 25th and 75th Percentile)

Variables

Cases

Controls

P-Value

Energy (kcal)

2,833 (2,433, 3,349)

2,907 (2,374, 3,748)

0.56

Energy/Weight (kcal/g)

 36 (32, 44)

 40 (34, 49)

0.16

Total Carbohydrate (g)

 359 (285,404)

 343(297, 462)

0.91

Percentage Calories from Carbohydrate 50 (45, 53) 47 (43, 51) 0.09
Sugars (g) 172 (152, 220) 163 (105, 227) 0.35
Starch (g) 138 (105, 171) 154 (105, 183) 0.62
Total Dietary Fiber (g) 19 (14, 23) 22 (18, 28) 0.08
Soluble Dietary Fiber (g) 7.0 (5.7, 8.6) 8.6 (7.0, 10.2) 0.02
Insoluble Dietary Fiber (g) 12.0 (8.9, 14.2) 13.9 (10.5, 18.0) 0.15
Pectin (g) 2.1 (1.3, 2.5) 2.6 (1.5, 3.5) 0.02
Average Glycemic Index per Meal 61 (57, 62) 59 (57, 62) 0.22
Average Glycemic Index per Day 61 (58, 62) 60 (58, 62) 0.54
Differences in Glycemic Index Range Within Each Day 20 (14, 26) 20 (18, 29) 0.12
Differences in Glycemic Index Range Between Days 10 (8, 14) 10 (8, 14) 0.86
Total Protein (g) 107 (95, 116) 122 (102, 146) 0.02
Percentage Calories from Protein 14 (13, 17) 17 (15, 18) 0.03
Protein/Weight (g/kg) 1.36 (1.18, 1.60) 1.62 (1.31, 1.97) 0.01
Total Fat (g) 122 (92, 129) 112 (93, 153) 0.53
Cholesterol (mg) 404 (313, 512) 429 (280, 595) 0.78
Percentage Calories from Fat 36 (33, 39) 35 (33, 40) 0.99
Percentage Calories from Saturated Fatty Acids 12 (10, 14) 12 (10, 14) 0.84
Percentage Calories from Monounsaturated Fatty Acids 13 (11, 15) 13 (12, 16) 0.48
Percentage Calories from Polyunsaturated Fatty Acids 7 (5, 8) 7 (6, 8) 0.66
Polyunsaturated-to-Saturated Fat Ratio 0.59 (0.42, 0.74) 0.59 (0.42, 0.77) 0.82
N-3 Fatty Acids (g) 1.93 (1.60, 2.77) 2.49 (1.81, 3.07) 0.12
Average Meal Number per Day 4.2 (3.7, 4.8) 4.5 (3.8, 5.7) 0.10

Other Findings

  • Both groups had a moderate dietary glycemic index
  • Small, but significant correlation between average glycemic index per day and total fiber and soluble fiber intake (-0.36 and -0.31, respectively; P<0.001).
Author Conclusion:
  • This study showed no association between HIV-associated fat deposition and dietary glycemic index
  • A more effective recommendation for patients with HIV might be to eat adequate dietary fiber, particularly a diet rich in fruits, vegetables and legumes, and low in processed foods, to possibly prevent development of fat deposition.
Funding Source:
Government: GCRC, NIDDK
Reviewer Comments:

Limitations as mentioned by authors:

  • Small number of men, so findings may not be applicable to women
  • Study focused on fat deposition, so findings may be 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
  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
  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
  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
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
  1. Was the research question clearly stated? Yes
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.1. 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
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
  1.3. Were the target population and setting specified? Yes
  2. Was the selection of study subjects/patients free from bias? 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
  2.1. 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
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? 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? ???
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
  3. Were study groups comparable? 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) N/A
  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
  3.2. 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
  3.3. 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
  3.4. 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
  3.5. 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
  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. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? N/A
  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
  4.2. 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
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.4. 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
  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. 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
  5.1. 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
  5.2. 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
  5.3. 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
  5.4. 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
  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. 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
  6.1. 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
  6.2. 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
  6.3. 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
  6.4. 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
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  6.6. Were extra or unplanned treatments 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
  6.7. 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
  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. 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
  7.1. 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
  7.2. 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
  7.3. 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
  7.4. 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
  7.5. 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
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? 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. 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
  8.1. 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
  8.2. 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
  8.3. 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
  8.4. 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
  8.5. 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
  8.6. 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
  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. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? 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. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes
  10.2. Was the study free from apparent conflict of interest? Yes