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H/A: Caloric Needs (2007)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
The aims of this study were to document the prevalence of weight loss and factors associated with it in a cross-sectional cohort of HIV-positive patients. The study sought to investigate whether lipodystrophy and inadequate intake are predictors of weight loss.
Inclusion Criteria:
None given.
Exclusion Criteria:
None given.
Description of Study Protocol:

Recruitment

All patients attending HIV-AIDS clinics of the Central Sydney Area Health Service were invited to participate.

Design

  • Cross-sectional
  • Patients were asked to describe if they had experienced changes in their body shape during management of HIV infection. This data was used to categorize the subjects reporting changes consistent with lipodystrophy syndrome from those not describing changes and to identify subjects with weight loss.

Blinding Used

Implied for measurements.

Statistical Analysis

  • Chi-square analysis was used to determine if the prevalence of weight loss was significantly different between those with and without lipodystrophy, with and without an adequate dietary intake and those taking or not taking antiretroviral therapy
  • Independent sample T-tests were used to determine if means of the variables measured were significantly different between those reporting and those not reporting weight loss
  • Forward stepwise logistic regression analysis was used to determine the predictors of weight loss. Factors entered into model were determined a priori to be dietary intake, CD4 cell count, HIV VL, age and presence or absence of lipodystrophy.
Data Collection Summary:

Timing of Measurements

November 1997 to November 1999, at one time point.

Dependent Variables

  • Weight loss was defined as greater than or equal to 5% of usual weight
  • Weight in light clothing
    • Weight history was obtained from patient and confirmed from patient's clinical record
    • Weight trend for the preceding 12 months prior to assessment was the basis for characterizing weight.

 Independent Variables

  • Height 
  • Waist-to-hip ratio
  • FFM and fat mass, by bioelectrical impedance
  • Fasting blood glucose
  • Total cholesterol
  • Triglycerides
  • Insulin and insulin resistance ratio
  • CD4 T-cell count, by flow cytometry
  • Viral load was measured using Chiron-Bayer b-DNA assay with a lower limit of detection of 500 copies per ml
  • Dietary intake was assessed using a validated self-administered food frequency questionnaire, developed specifically for use in this population 
  • Peripheral lipodystrophy syndrome was defined as self-reported disproportionate peripheral subcutaneous fat wasting involving the limbs or face or development of central adiposity and was confirmed by clinical examination.

Control Variables

Included in independent variables during regression.
Description of Actual Data Sample:
  • Initial N: 122 (four female, 118 male)
  • Attrition (final N): 122
  • Age: 40.4±9.0 years (21 to 65)
  • Ethnicity: Not given
  • Other relevant demographics: None given.

Anthropometrics

  • Weight: 71.5±12.2kg (44.0 to 104.0)
  • Disease information
    • Viral load: 3.5±1.1 (1.7 to 5.9) log copies per ml
    • CD4 T-cell count: 345±312 (zero to 1,500) cells per uL
  • 100 taking antiviral therapy with 76 on regimens, including a protease inhibitor. Seven subjects were taking a sub-optimal dual regimen for reasons of poor drug tolerance or lifestyle choices.

Location

Clinics of the Central Sydney Area Health Service.

Summary of Results:

 Table One: Differences Between Those With and Without Preceding Weight Loss

Variables

Weight Loss (N=49)
Mean (SD)

No Weight Loss (N=73)
Mean (SD)

P (T-Test)

Age (Years)

39.7 (8.1)

41.4 (10.1)

0.305

Weight (kg)

67.75 (12.70)

74.07 (11.30)

0.005

BMI (kg/m2)

21.83 (3.21) 

24.19 (3.23) 

<0.001 
FFM (kg) 55.87 (8.31) 59.52 (7.54) 0.013
FM (Percentage) 16.89 (4.53) 19.26 (4.43) 0.005
Viral Load (Log Copies/ml) 3.84 (1.27) 3.29 (0.96) 0.008
CD4 T-Cell Count (cells/uL) 256 (227) 361 (224) 0.016
Intake (kJ) 12,809 (4,295) 13,058 (5,248) 0.783
Intake (Percentage of Estimated Requirements; Harris-Benedict Equation) 117 (47) 112 (48) 0.570

Table Two: Comparison of Number (and Percentages) of Those With and Without Weight Loss and With or Without Lipodystrophy, Using or Not Using Antiretroviral Therapy, Adequate or Inadequate Intake

Variables

Weight Loss (N=49)
Number (Percentage)

No Weight Loss (N=73)
Number (Percentage)

P-Value (Chi-Square)

Lipodystrophy (N=49)

17 (34.7)

32 (65.3)

 

No Lipodystrophy (N=73)

32 (43.8)

41 (56.2)

0.313

Taking Antiretrovirals (N=100)

34 (34.0)

66 (66.0)

 
Antiretroviral Naive (N=22) 15 (68.2) 7 (31.8) 0.003
Adequate Intake (≥ 100% of Estimated Requirements*) (N=70) 32 (45.7) 38 (54.3)  
Inadequate Intake (<100% of Estimated Requirements*) (N=52) 17 (32.7) 35 (67.3) 0.147

*Calculated using the Harris-Benedict equation

Other Findings

  • 40.2% of subjects lost weight
  • Mean weight loss: 6.6kg (SD=4.2kg, range two to 20kg)
  • Amongst those taking antiretroviral therapy, there was no significant difference in the prevalence of weight loss, according to their use of PI-containing regimens (31.2% for PI regimens, compared with 43.5%; P=0.274)
  • 13 subjects had a BMI below 20kg per m2; 10 of these had lost weight
  • 40.2% of subjects reported lipodystrophy
  • Significantly greater in those reporting lipodystrophy
    • Mean waist-to-hip ratio: 0.97±0.08 vs. 0.89±0.06, P<0.001
    • Fasting blood glucose: 5.10±0.57 vs. 4.83±0.55mmol per L, P=0.011
    • Serum cholesterol: 6.44±2.82 vs. 4.70±1.34mmol per L,P<0.001
    • Serum triglycerides (5.50±7.35 vs. 1.81±1.25mol per L, P<0.001
    • Serum insulin: 102.41±65.97 vs. 56.43±53.59pmol per L
    • Insulin resistance ratio: 3.24±2.11 vs. 1.69±1.85mmol2 per L2, P<0.001.
  • Only VL was included in the forward stepwise model. Every one log increase in HIV VL was associated with an odds of weight loss of 1.58 (P=0.008).
  • Dietary intake not significantly different between those with and without weight loss, nor was the percentage of subjects with an adequate intake significantly different between those without weight loss.
Author Conclusion:
  • Main findings in this study were that weight loss is still common in the HAART era and that HIV VL was the best predictor of impending weight loss in this sample population
  • Occurence of weight loss was more frequent in those who were antiretroviral naive
  • Results suggest weight loss is independent of dietary intake in this patient group
  • Authors postulated that although inadequate intake would lead to weight loss, the effects of increasing HIV viraemia overpower any dietary attempts to abrograte weight loss
  • Weight loss occurred independently of the presence of peripheral lipodystrophy syndrome
  • Subjects with high or increasing VL are at risk of weight loss and should be monitored closely.
Funding Source:
Reviewer Comments:
  • Findings may not be applicable to women, due to the small number of women (four) included in the study
  • Did not use food records or recalls for assessing dietary intake versus a food frequency questionnaire.
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? No
  2.2. Were criteria applied equally to all study groups? N/A
  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) 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? ???
  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? 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? Yes
  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? 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? 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? 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)? 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? 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