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H/A: Body Composition Measurement (2009)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

Authors tested the hypothesis that malnutrition as re­flected by altered electrical tissue conductivity and basic serum nutritional parameters has a relevant impact on long-term survival (1,000 days) in HIV-infected patients who do not have AIDS.

Inclusion Criteria:
  • Male outpatients at all stages of HIV infection
  • At the time of nutritional assessment, 85 of these patients were classified as Walter Reed  three to five according to the classification system (they were HIV-positive with or without lymphadenopathy, and T-helper cells were less than 400 per µL).
Exclusion Criteria:

Patients with opportunistic infections or other AIDS-defining factors present.

Description of Study Protocol:

Recruitment

325 outpatients were seen as part of an initial nutritional assessment program performed from March 1990 to July 1990 as a part of routine services. 85 subjects were classified as Walter Reed three to five, and 75 of the 85 were available for follow-up.  

Design

Prospective cohort. Patients were prospectively evaluated for survival in the institution over a follow-up period of 1,000 days for each patient.

Statistical Analysis

  • Pre-therapeutic factors: Survival regression analysis (the Cox model)
  • Prognostic influence: Semi-parametric Cox regression model (with co-variates) and likelihood ratio test
  • Survival time and life table analysis of HIV-infected patients: Kaplan and Meier methods.

 

Data Collection Summary:

Timing of Measurements

Baseline and follow-up (1,000 days) of survivors.

Dependent Variables

Long-term survival (1,000 days).

Independent Variables

  • Nutritional parameters (weight; BMI; serum concentrations of protein, albumin,cholesterol and triglycerides)
  • Bioelectrical impedance analysis data.

 Control Variables

 Adjusted for therapy.

Description of Actual Data Sample:
  • Initial N: 352 male outpatients. 85 were classified as Walter Reed three to five.
  • Attrition (final N): 75 HIV infected patients. 29 of the 75 died during the 1,000 days.
  • Age: Mean age was 38.9 years.

Other Relevant Demographics

  • Mean CD4 cell count: 176.2±124.1 x 106 cells per L 
  • 34 patients received treatment with azidothymidine (Retrovir, 500 to 1,000mg per day) and 38 patients performed prophylactic inhalation with pentamidine (Pentacarinat 200mg every 14 days) for at least three months prior to the study.

Location

Germany.

 

Summary of Results:

Among 12 parameters estimated with a semi-parametric Cox regression model adjusted for therapy, the phase angle alpha, the ECM to BCM ratio, Xc, BCM, serum cholesterol, number of CD4+ cells and serum albumin had significant prognosis influence on survival, whereas age, body weight, BMI, resistance, serum protein, cell count was lower compared with the phase angle alpha and did not gain statistical significance.

The phase angle alpha was the best single predictive factor for survival among all 12 parameters.

Parameter

All patients
(N=75)
 

Survivors/Non-survivors

(N=46)/(N=29)                 P-value
 
Age (years)
38.9±9.1
 
37.6±10.4               41.9±10.3               0.0513
 
Body weight (kg)
71.9±9.6
 
73.4±10.1               69.5±7.9               0.0423
 
Body mass index (kg/m2)
23.0±2.8
 
23.4±3.0               22.4±2.2               0.1670
 
CD4+ cells (x 106 per L)
176.2±124.1
 
222.8±112.8             102.1±99.0             0.0001
 
Total protein (g per L)
78.3±6.3
 
78.0±6.1               79.1±7.2               0.7810
 
Albumin (g per L)
42.5±3.8
 
43.6±3.1               41.1±4.0               0.0042
 
Cholesterol (mmol per L)
4.2±1.0
 
3.8±0.9    4.6±0.9                0.0007
 
Triglycerides (mmol per L)
1.6±0.7
 
1.6±0.7    1.7±0.7                 0.3607
 
Resistance (4,)
510.7±58.1
 
506.5±51.7             517.2±49.2             0.5244
 
Reactance (f2)
47.7±7.8
 
50.5±6.8               43.2±6.9               0.0001
 
Phase angle (°)
5.4±0.8
 
5.8±0.6     4.8±0.7                 0.0001
 
Body cell mass (kg)
28.6±4.8
 
30.3±4.4               26.1±4.0               0.0002
 
ECM to BCM
1.1±0.2
 
1.0±0.1     1.3±0.3                 0.0001
 
 

Author Conclusion:

 

Body composition as reflected by the phase angle alpha is a major determinant of long-term survival in HIV infection, thereby representing an important parameter for monitoring disease progression.

We conclude that alterations in bioelectrical tis­sue conductivity measured by tetrapolar BIA are important implications for long-term prognosis in HIV-infected patients at WR stages three to five. Longitudi­nal studies with serial measurements should be ini­tiated to evaluate whether reiterative impedance analysis might further improve the individual prog­nostic impact of this method.

Funding Source:
Government: Bundesministerium fur Forschung and Technologie (German Ministry for Research and Technology
Reviewer Comments:
  • Limited information regarding recruitment or location
  • Limited information regarding ethnicity
  • Limited information regarding population, sample selection
  • Small sample
  • Limitations of study were not discussed in detail.
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? ???
  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? Yes
  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? ???
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? ???
  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? ???
  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? 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? 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? No
  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