Unintended Weight Loss in Older Adults

Healthy Non-Obese Adults (2010-2012)

Citation:

Luhrmann PM, Neuhaeuser Berthold M.  Are the equations published in literature for predicting resting metabolic rate accurate for use in the elderly?  J Nutr Health Aging 2004;8(3):144-9.

PubMed ID: 15129299
 
Study Design:
Cross-Sectional Study
Class:
D - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To validate various predictive equations by comparing calculated RMR with measured RMR in a large group of elderly subjects.

Inclusion Criteria:
  • At least 60 years old
  • Physically mobile
  • Available around Giessen on a long term basis
  • Complete data on RMR, anthropometrical measurements, diseases and medications
Exclusion Criteria:
  • Subjects suffering from hypothyroidism, hyperthyroidism or who took thyroid medications
Description of Study Protocol:

Recruitment

Subjects were participants of a longitudinal study on nutrition and health status in an aging population of Giessen, Germany.  Subjects were recruited by physicians, notices, senior citizens meetings, advertisements in local newspapers, and by recruitment through subjects who had already been participants.

Design:  Cross-Sectional Study 

Blinding used (if applicable):  not applicable 

Intervention (if applicable):  not applicable 

Statistical Analysis

Data were checked concerning normal distribution using Kolmogorow-Smirnow test.  Deviations between measured RMR and RMR predicted with equations published in the literature were examined by t test for paired samples.  To test if deviations between measured and predicted RMR differ between separate BMI groups or between sokers and non-smokers, ANOVA and unpaired t tests were used.  To determine the associations between measured and predicted RMR, Pearson's correlations as well as Bland-Altman plots were used.  Data are presented as mean, standard deviation and 95% confidence intervals.

Data Collection Summary:

Timing of Measurements

Nutritional and health status of free-living elderly people has been investigated at annual or biannual intervals since 1994.

Dependent Variables

  • RMR measured by indirect calorimetry after an overnight fast with standard protocol 
  • Body weight, height, BMI
  • Body composition

Independent Variables

  • Age
  • Diseases
  • Medication
  • Smoking behavior all collected through questionnaire

Control Variables

 

Description of Actual Data Sample:

Initial N:  375 females and 158 males took place in the study from 1994 to 2000

Attrition (final N):  225 females and 130 males

Age:  females mean age:  67.7 +/- 5.7 years, males mean age:  67.4 +/- 5.4 years 

Ethnicity: not mentioned

Other relevant demographics:  see Results

Anthropometrics:

Location: Germany

 

Summary of Results:

 

 

RMR (kJ/day)

Difference (kJ/day)

Difference (%)

Pearson Correlation
Females - Measured RMR 5580 +/- 690 -- -- --

Schofield 1

5357 +/- 402

-224 +/- 464,  P < 0.001

-3.3 +/- 7.6

0.76, P < 0.001
Schofield 2 5404 +/- 396 -176 +/- 464, P < 0.001 -2.4 +/- 7.6 0.77, P < 0.001
WHO 1 5504 +/- 465 -76 +/- 452, P < 0.001 -0.7 +/- 7.7 0.76, P < 0.001
WHO 2 5642 +/- 475 61 +/- 451, P < 0.001 1.8 +/- 7.7 0.76, P < 0.001
Harris-Benedict 5399 +/- 472 -181 +/- 450, P < 0.001 -2.6 +/- 7.4 0.72, P < 0.001
Males - Measured RMR 6950 +/- 934 -- -- --
Schofield 1 6366 +/- 506 -583 +/- 689, P < 0.001 -7.5 +/- 8.1 0.69, P < 0.001
Schofield 2 6573 +/- 545 -376 +/- 754, P < 0.001 -4.5 +/- 9.4 0.59, P < 0.001
WHO 1 6545 +/- 584 -405 +/- 678, P < 0.001 -5.0 +/- 8.4 0.69, P < 0.001
WHO 2 6614 +/- 566 -335 +/- 769, P < 0.001 -3.9 +/- 9.7 0.57, P < 0.001

Harris-Benedict

6585 +/- 684

-365 +/- 675, P < 0.001

-4.6 +/- 8.6

0.69, P < 0.001

Other Findings

Mean measured RMR was 5580 kJ/day in females and 6950 kJ/day in males.

In females and males, RMR was on average underestimated by 3.3% and 7.5% with the Schofield equation based on body weight, by 2.4% and 4.5% with the Schofield equation based on both weight and height, by 0.7% and 5.0% with the WHO equation based on body weight, and by 2.6% and 4.6% with the Harris-Benedict equation, respectively.

RMR calculated with the WHO equation based on body weight and height was 1.8% higher in females and 3.9% lower in males compared to measured RMR.

Regarding all predictive equations the difference between predicted and measured RMR were negatively correlated with measured RMR and were partly more pronounced in smokers and obese subjects than in non-smokers and subjects with a BMI < 30. 

Author Conclusion:

In summary, on the group level, the WHO, the Schofield, and the Harris-Benedict predictive equations results in rather accurate mean predicted values and therefore provide valid estimates of RMR.  However, on an individual basis, all predictive equations used demonstrate considerable variability between predicted and measured RMR.  Thus for individuals RMR should be measured instead of estimated.  Where measurements cannot be taken, population specific equations should be used for predicting RMR.  For calculation, RMR in elderly German subjects we recommend using an equation that was developed on the basis of the data determined in our large group of elderly subjects and that is both easy and accurate for use in practice.

Funding Source:
University/Hospital: University of Giessen (Germany)
Reviewer Comments:

Authors note that the observed differences between measured and predicted RMR were not caused by the variations in the methods.

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? 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? 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? Yes
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? 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? 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? 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)? 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