H/A: Caloric Needs (2007)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To investigate body composition, stress hormone release, and interleukin-6, tumor necrosis factor, and sTNFR-55 and sTNFR-75 plasma concentrations during acute infectious complications of advanced HIV disease.
Inclusion Criteria:
  • Patients between 18 and 70 years of age
  • Proven HIV infection
  • Hospitalization for acute infectious complications of HIV disease.
Exclusion Criteria:
  • Malignancies requiring systemic drug treatment
  • Impaired renal function
  • Immune modulating therapy.
Description of Study Protocol:
  • Recruitment: Methods not specified
  • Design: Longitudinal study.

Statistical Analysis

  • Student's T-tests for paired and unpaired data were used for statistical analyses
  • ANOVA was used to test for changes of parameters throughout the study
  • REE and the deviation of measured from predicted REE were used as dependent variables in stepwise regression analyses
  • Serum values of TNF, CrP and IL-6 that were undetectable were assigned the value of the detection limit for purposes of statistical analyses.
Data Collection Summary:

Timing of Measurements

  • All patients admitted for acute infectious complications of HIV and baseline values taken
  • Measurements were repeated four times every two days for study Days Two through Five.

Dependent Variables

  • Lymphocyte subset analysis, through standard fluorescence-activating cell sorting
  • Total body water and body composition measured through bioelectrical impedance
  • Resting energy expenditure measured through indirect calorimetry
  • C-reactive protein and total iron-binding capacity measured by kinetic nephelometry
  • Urinary nitrogen analyzed by chemiluminescence
  • TNF measured through TNF enzyme-amplified sensitivity immunoassay
  • IL-6 measured with ELISA
  • sTNFR-55 and sTNFR-75 measured through enzyme-linked immunological and biological binding assays
  • Thyrotropin measured using ultrasensitivity fluorometric enzyme immunoassay
  • Urinary catecholamines separated by HPLC. 

Independent Variables

HIV infection with acute infectious complications.
Description of Actual Data Sample:
  • Initial N: 12 patients; 11 male, 1 female
  • Attrition (final N): 12
  • Mean age: 39±7 years
  • Ethnicity: Not mentioned
  • Location: Germany.

 

Summary of Results:

Other Findings

  • TNF was closely correlated with sTNFR-75 concentration (R=0.84, P<0.001), whereas the sTNFR-to-sTNFR-55 ratio increased throughout the study
  • TNF concentrations were significantly correlated with the 24-hour excretion of epinephrine and norepinephrine (R=0.64 and 0.69, each P<0.01)
  • Compared to expected values, REE was increased by 34%
  • REE did not change during the study period and was similar for all five measurements (mean 2,054±469kcal per day)
  • Body cell mass was the only significant predictor of REE and explained 72% of its variance
  • In contrast, the deviation of measured from predicted REE was correlated with TNF and IL-6 concentrations (R=0.9).
Author Conclusion:
  • We conclude that the release of cytokines, especially TNF, is continuously raised in HIV-infected patients during acute opportunistic infection and correlates with a significant increase of REE. This effect may be mediated by catecholamines, especially epinephrine.
  • For clinical practice, the 75-kD TNF receptor (sTNFR-75) is a practical and probably useful marker to estimate TNF release in vivo. However, resting energy expenditure itself is mainly explained by body cell mass.
  • Our data substantiate the original concept of the body cell mass by Moore et al as the main determinant of nutritional requirements, oxygen consumption, carbon dioxide output and work capacity.
Funding Source:
Reviewer Comments:
  • Small sample size
  • Recruitment methods not specified
  • Detectable values assigned for undetectable variables.
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? ???
  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? 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? N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) 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.) 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
  4.1. 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? 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? 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? ???
  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? N/A
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)? N/A
  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? ???
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? No
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