EAL

H/A: Caloric Needs (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To investigate the determinants of energy expenditure in HIV-infected women.

Inclusion Criteria:

None specifically mentioned
Cases: Ambulatory, premenopausal HIV-infected women
Controls: Weight-matched, premenopausal healthy controls.

Exclusion Criteria:

None specifically mentioned
All subjects free of any acute opportunistic infection within six weeks of study
None of the subjects were gaining weight at the time of the investigation nor had been taking megestrol acetate, estrogen, ketoconazole, glucocorticoid or an anabolic agent within three months of admission
None of the HIV-infected subjects began taking a new retroviral agent or protease inhibitor within six weeks of study initiation.

Description of Study Protocol:

Recruitment

Methods not described.

Design

Case-control study.

Statistical Analysis

Characteristics compared between groups using Student's T-test and within the HIV-infected and control groups by univariate regression analysis
Regression equations for REE and FFM were analyzed separately for HIV-infected and control groups and compared by ANCOVA
Stepwise regression analyses were performed separately for the HIV-infected and control groups.

Data Collection Summary:

Timing of Measurements

Measurements made in cases and controls and compared.

Dependent Variables

Resting energy expenditure determined by indirect calorimetry
Body composition by DEXA, bioelectrical impedance analysis and skinfold-thicknesses
Hormonal indices included leptin, testosterone, estradiol, insulin-like growth factor-1, gonadotropin, sex-hormone binding globulin, dehydroepiandrosterone sulfate, mean overnight growth hormone, triiodothyronine and free thyroxine
Dietary intake measured through four-day food record
Menstrual history
Immune function determined by CD4 count and viral load.

Independent Variables

HIV infection.

Description of Actual Data Sample:

Initial N: 33 HIV-infected women, 26 healthy controls
Attrition (final N): 33 cases, 26 controls
Age: See Results
Ethnicity: Not mentioned
Other relevant demographics: HIV-infected subjects had lost 13.9% of body weight during three months before the study and 61% were characterized as wasted by CDC
Anthropometrics: Controls were weight-matched
Location: Boston.

Summary of Results:

	HIV-Infected Subjects	Control Subjects	HIV-Wasted Subjects	HIV-Non-Wasted Subjects
Age (Years)	35.6±5.4	24.2±3.0, P<0.001	36.7±5.3	34.1±5.3
Weight (kg)	59.2±8.8	58.7±6.7	55.1±7.8	65.5±6.3, P<0.001
Height (cm)	163.7±6.3	166.3±7.6	164.3±7.4	162.9±4.2
BMI	22.1±3.3	21.2±1.5	20.5±2.9	24.6±2.0, P<0.001
IBW (Percentage)	99.3±14.6	96.8±6.5	92.1±12.6	110.2±10.0, P<0.001
REE (kJ/Day)	6794±1374	6011±607, P = 0.01	6643±1645	7020±836
Predicted REE (%)	119±23	102±9, P < 0.001	120±28	119±15
Energy Intake (kJ/Day)	10719±3259	9275±2513	10604±3381	10897±3200
EI-REE (kJ/Day)	3918±3286	3269±2415	3946±3444	3877±3182
Total Testosterone (nmol/L)	0.7±0.4	1.1±0.5, P<0.001	0.6±0.2	0.9±0.5, P=0.047
Free Testosterone (pmol/L)	2±2	4±3, P=0.001	2±1	3±2
Leptin (ug/L)	12.0±8.9	10.8±5.3	10.3±9.4	14.8±7.4
IGF-1 (ug/L)	206±95	271±89, P=0.009	208±108	202±74
Estradiol (pmol/L)	152±125	104±36	147±110	162±151
Albumin (g/L)	33±4	41±2, P<0.001	33±5	34±3
CD4 (x10⁶/L)	369±234	NA	317±169	452±301
Viral Load (Copies/L)	82.6±179.4	NA	118.9±220.0	26.7±59.3
Weight Change (Percentage)	12.8±8.4	NA	17.5±6.5	4.8±4.0, P<0.001
FFM (kg, DXA)	39.2±4.5	39.9±4.2	38.6±4.7	40.4±3.9
FFM (kg, BIA)	43.8±4.6	44.4±3.9	42.5±4.8	45.9±3.4, P=0.038
FFM (kg, SKF)	43.4±4.5	44.3±4.5	41.7±4.6	46.0±2.9, P=0.005
Fat Mass (kg, DXA)	17.5±7.9	15.6±3.0	14.4±6.6	22.6±7.2, P=0.002
Fat Mass (kg, BIA)	15.4±6.3	14.3±3.6	12.6±5.3	19.6±5.4, P<0.001
Fat Mass (kg, SKF)	15.8±5.4	14.4±3.1	13.5±4.5	19.5±4.9, P<0.001

Other Findings

HIV-infected subjects had a higher REE than control subjects (6,794±1,374, compared with 6,011±607 kJ per day; 1,624±329, compared with 1,437±145 kcal per day; P=0.0096)
On average, REE was 119±23% of Harris-Benedict predictions in HIV-infected subjects compared with 102±9% for control subjects (P=0.0007)
In HIV-infected subjects, REE was highly correlated with fat-free mass by DEXA (R=0.641, P<0.001), but not with weight or disease status
The slope of the regression equation for REE and FFM was significantly greater (P=0.27, ANCOVA) for HIV-infected subjects [REE (kJ per day)=203.5 (kg FFM)-1,237] than for control subjects [REE (kJ per day)=77.4 (kg FFM)+2,923]
In a stepwise regression analysis, FFM was the most significant variable (P=0.005), followed by free testosterone (P=0.029), which together explained 49% of variation in REE
The final equation was REE (kJ per day)=230.8 (kg FFM)+395.9 (free testosterone, pmol per liter)-3,304.

Author Conclusion:

In summary, this was the first study to investigate energy expenditure in HIV-infected women and to show that REE is higher in this population than in healthy subjects
Increased REE may play a role in the wasting syndrome and contribute to weight loss in the setting of decreased energy intake during secondary infection in HIV-infected women
Further studies are needed to define the mechanisms of increased energy expenditure in HIV-infected subjects.

Funding Source:

Reviewer Comments:

Inclusion and exclusion criteria and recruitment methods not described.

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?	No
	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?		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?	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
	3.5.	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
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?		???
	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