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CI: Best Method to Estimate RMR (2010)

Citation:

Barak N, Wall-Alonso E, Sitrin MD.  Evaluation of stress factors and body weight adjustments currently used to estimate energy expenditure in hospitalized patients.  JPEN 2002; 26(4):231-8. 

PubMed ID: 12090688
 
Study Design:
Cohort Study
Class:
B - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To critically examine current approaches for estimating energy expenditure and requirements of hospitalized patients requiring nutrition support.
Inclusion Criteria:
Patients 16 years or older.
Exclusion Criteria:
None specifically mentioned.
Description of Study Protocol:

Recruitment

All indirect calorimetry tests performed from 1991 to 2000 were reviewed.

Design

Cross-Sectional Study.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Indirect calorimetry measurements.

Statistical Analysis

Data expressed as means +/- SD.

Data Collection Summary:

Timing of Measurements

Retrospective review of indirect calorimetry measurements.

Dependent Variables

  • RMR measured with Deltatrac Metabolic Monitor, measurements performed for 30 minutes with the first 10 minutes being omitted, and last 20 minutes averaged to calculate MEE
  • RMR estimated using Harris-Benedict equation
  • RMR estimated using Cunningham equation
  • Stress factors were calculated as the measured EE divided by the predicted EE using the Harris-Benedict equation
  • Ideal body weight calculated according to Hamwi equations
  • Adjusted body weight defined as the IBW plus a percentage of difference between actual and ideal body weights 

Independent Variables

  • Age
  • Height
  • Weight
  • Primary diagnosis
  • Most recent body temperature
  • Ventilation
  • Fasting or receiving parenteral or enteral support
  • Degree of restlessness during the measurement period

Control Variables

 

Description of Actual Data Sample:

Initial N: 567 measurements, 294 on men, 273 on women

Attrition (final N):  567

Age:  Men:  mean 54 +/- 17 years, women:  mean 53 +/- 17 years

Ethnicity:  not mentioned

Other relevant demographics:  Men:  mean BMI:  26.6 +/- 10.4, women:  mean BMI: 29.3 +/- 12.1

Anthropometrics:

Location:  Chicago

 

Summary of Results:

 Calculation of Stress Factors

  BMI < 18.5 BMI 18.5 - 30 BMI > 30
Men - Actual Weight 1.24 +/- 0.25 1.24 +/- 0.25 1.10 +/- 0.22

Men - IBW

0.98 +/- 0.28

1.22 +/- 0.27

1.55 +/- 0.35

Men - 25% Adjusted

 

 

1.39 +/- 0.26

Men - 33% Adjusted     1.35 +/- 0.25
Men - 50% Adjusted     1.28 +/- 0.23
Women - Actual Wt 1.19 +/- 0.26 1.26 +/- 0.26 1.09 +/- 0.28
Women - IBW 1.07 +/- 0.25 1.34 +/- 0.31 1.53 +/- 0.40
Women - 25% Adjusted     1.38 +/- 0.35
Women - 33%     1.34 +/- 0.34
Women - 50% Adjusted     1.26 +/- 0.32

 Other Findings

The mean +/- SD of the MEE for the men was 2078 +/- 633 kcal/day and for women was 1682 +/- 474 kcal/day.

The average stress factor for these normal weight hospitalized patients was 1.25, and there were no differences in the stress factors between men and women (1.24 +/- 0.25 for men, 1.26 +/- 0.26 for women).

For obese subjects, using an adjusted body weight equal to IBW plus 50% of the difference between IBW and actual body weight in the Harris-Benedict equation gave stress factors comparable with normal weight subjects.

For underweight subjects (BMI < 18.5), using the actual rather than ideal body weight gave stress factors that were most similar to normal weight patients (actual weight men: 1.24 +/- 0.25 for men and 1.19 +/- 0.26 for women). 

Disease-specific stress factors were calculated and compared with literature values.  Mechanical ventilation, recent feeding, fever and restlessness during the indirect calorimetry measurement increased the measured energy expenditure.

Complicated surgery:  1.25 to 1.4

Sepsis: 1.30 to 1.35

Infections:  1.25 to 1.45

Burns:  1.60

Solid tumors:  1.20

Leukemia/lymphoma:  1.25

IBD:  1.05 to 1.10

Pancreatitis:  1.10 to 1.20

Liver disease:  1.00 to 1.05

 

Author Conclusion:
Our findings provide nutrition support services with updated information on disease-specific stress factors that can be used for estimating energy expenditure in hospitalized patients.  An adjusted body weight equal to ideal body weight plus 50% of the excess body weight should be used for estimating the energy requirements of obese patients requiring nutrition support.
Funding Source:
University/Hospital: University of Chicago, Beilinson Hospital
Reviewer Comments:
Data collected over 9 years.  Inclusion/exclusion criteria not well defined.  IC protocol not well described.  Statistical analysis not highly sophisticated.
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? Yes
  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? 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? Yes
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) 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? Yes
  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? N/A
  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.) N/A
  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? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  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? 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? Yes
  6.6. Were extra or unplanned treatments described? Yes
  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? ???
  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? 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