H/A: Caloric Needs (2007)
Citation:
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To investigate whether resting energy expenditure is elevated in early asymptomatic HIV-infected females and to study the contribution of a cytokine (tumor necrosis factor-alpha) to hypermetabolism.
Inclusion Criteria:
Cases were HIV-infected, controls were not
Exclusion Criteria:
- Subjects with fever
- Impaired kidney function
- Known endocrinological disease
- History of opportunistic infections or malignancy
- Subjects with current or prior usage of one or a variety of medications including retroviral medications or other immune modulators, anabolic steroids and antidepressant drugs known to affect metabolism.
Description of Study Protocol:
- Recruitment: Methods not described
- Design: Case-control study.
Statistical Analysis
- ANOVA and ANCOVA used to assess differences in descriptive characteristics, REE and substrate utilization
- Pearson correlations were performed to study the correlation of TNF-alpha and the CD4 count with REE
- Regression analysis was used to examine the correlation between TNF-alpha and the CD4 cell count.
Data Collection Summary:
Timing of Measurements
Measurements made in cases and controls and compared.
Dependent Variables
- Weight, height, BMI
- REE measured through indirect calorimetry
- 24-hour urinary nitrogen calculated to correct RQ
- Body composition measured through bioelectrical impedance and skinfold measurements
- TNF-alpha measured by ELISA
- Dietary intake through three-day food records, reviewed by RD.
Independent Variables
HIV infection.Description of Actual Data Sample:
- Initial N: 26 subjects; 10 asymptomatic HIV-infected females, 16 healthy controls
- Attrition (final N): 10 cases, 16 controls
- Mean age: Cases, 35±7 years; controls, 34±9 years
- Ethnicity: Not mentioned
- Other relevant demographics: Mean CD4 count = 636/mm3
- Anthropometrics: Controls matched for age, BMI and fat free mass
- Location: Delaware.
Summary of Results:
HIV-Infected (N=10) |
Controls (N=16) |
P-Value |
|
Age (years) | 35.2±7.2 | 33.7±8.6 | 0.66 |
Height (cm) | 164.5±5.4 | 164.1±7.7 | 0.90 |
Weight (kg) | 99.5±33.3 | 78.1±15.9 | 0.04 |
FFM (kg) | 56.2±4.3 | 50.2±6.5 | 0.14 |
Fat Mass (kg) | 43.3±19.9 | 27.9±10.0 | 0.01 |
Percentage Body Fat | 41.6±7.0 | 34.9±5.7 | 0.01 |
BSA (m2) | 2.0±0.3 | 1.8±0.2 | 0.06 |
BMI |
36.4±11.3 |
29.2±7.1 |
0.06 |
Waist-to-Hip Ratio |
0.79±0.04 |
0.79±0.05 |
0.70 |
Absolute REE (kcal/Day) | 1,755±410 | 1,497±197 | 0.05 |
REE (kcal/kg) | 31.4±1.75 | 29.9±2.5 | 0.04 |
RQ | 0.80±0.03 | 0.79±0.02 | 0.89 |
Urinary Nitrogen (g/Hour) | 4.7±2.7 | 7.8±2.9 | 0.01 |
Kcal/24-Hours | 1,919.7±562 | 1,903±516 | 0.94 |
Kcal/kg/24-Hours | 24.7±18.0 | 26.3±10 | 0.78 |
Carbohydrate (g) | 209.7±73.1 | 254.1±96.3 | 0.23 |
Carbohydrate (%) | 45.3±4.6 | 54.0±7.9 | 0.002 |
Fat (g) | 88.4±31.9 | 64.1±20.3 | 0.03 |
Fat (%) | 40.6±4.9 | 30.4±6.3 | 0.0002 |
Protein (g) | 85.6±35.7 | 69.6±20.1 | 0.15 |
Protein (%) | 15.7±3.0 | 15.2±3.4 | 0.77 |
Other Findings
- Absolute REE was 17% higher (1,755kcal per kg ±410 vs. 1,497kcal per kg ±197) in the HIV-infected group, compared with the control group (P<0.05)
- REE remained significantly higher in the HIV-infected group when REE was adjusted for body composition differences (P=0.04)
- Results revealed a 23% higher level of TNF-alpha in the HIV-infected subjects (P<0.01), however only a weak correlation existed between TNF-alpha and REE (R=0.352).
Author Conclusion:
- The etiology of hypermetabolism is complex and investigations of all possible interventions that will enable the HIV-infected patient to maintain weight are of vital importance
- Despite the weak correlation between TNF-alpha and REE, it is significant that we found TNF-alpha to be significantly elevated in the asymptomatic HIV-infected female
- Future research should focus on the interaction of several cytokines that regulate immunity and are involved in metabolism. Longer-term studies inclusive of females could more precisely determine the significant relevance of these cytokines to hypermetabolism. Furthermore, since increased REE and increased levels of proinflammatory TNF-alpha were present in the HIV-infected group, continued research investigating TNF-alpha cytokine inhibitors in the HIV population is suggested.
Funding Source:
Reviewer Comments:
- Small groups
- Recruitment methods not described
- Controls were significantly different for certain baseline characteristics that would affect REE, such as weight.
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? | Yes | |
2.2. | Were criteria applied equally to all study groups? | ??? | |
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? | No | |
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? | 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? | 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? | 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? | 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? | 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 | |
7.6. | 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 | |