Unintended Weight Loss in Older Adults

UWL: Caloric Needs (2007)

Citation:

Meunier N, Beattie JH, Ciarapica D, O'Connor JM, Andriollo-Sanchez M, Taras A, Coudray C, Polito A.  Basal metabolic rate and thyroid hormones of late-middle-aged and older human subjects:  the ZENITH study.  Eur J Clin Nutr 2005;59:S53-S57.

PubMed ID: 16254583
 
Study Design:
Cross-Sectional Study
Class:
D - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To describe baseline data on BMR, body composition and thyroid hormone levels of middle-aged and older people participating in the ZENITH project and the correlation of thyroid hormone levels with zinc status.

Inclusion Criteria:

None specifically mentioned.

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment

Screening and enrollment procedure not described in this paper; described elsewhere.

Design:  cross-sectional analysis of baseline data from a multicenter prospective intervention study with randomized design 

Blinding used (if applicable):  not applicable; study was double blind 

Intervention (if applicable):  not applicable

Statistical Analysis

Two-way ANOVA used to test the main effects of sex and age at 2 different centers.  BMR data were also analyzed using a two-way ANCOVA with body weight and FFM as independent variables.  Relationships between BMR and age, body composition or thyroid hormones and between thyroid hormones with zinc status were determined by regression analysis.

Data Collection Summary:

Timing of Measurements

Measurements made at study baseline.

Dependent Variables

  • BMR measured by indirect calorimetry under standardized conditions
  • Thyroid hormone levels (total T3 and T4) measured using competitive immunoassay with an enhanced chemiluminescence end point
  • Fat free mass derived by 4 skinfold thicknesses using Durnin and Womersley's equations

Independent Variables

  • Sex
  • Age
  • Body weight
  • FFM

Control Variables

  • FFM
Description of Actual Data Sample:

Initial N: 70 middle-aged volunteers (35 women, 35 men) and 108 older volunteers (56 men, 52 women) had BMR measurements, thyroid hormone levels evaluated in all 387 ZENITH volunteers 

Attrition (final N):  as above

Age:  middle aged volunteers aged 55 - 70 years, older volunteers aged 70 - 85 years 

Ethnicity: not mentioned

Other relevant demographics:

Anthropometrics:

Location:  France, Northern Ireland and Italy 

 

Summary of Results:

 

 

Middle Aged Men (n=35) Middle Aged Women (n=35) Older Aged Men (n=56) Older Aged Women (n=52)

Fat mass (kg)

19.9 +/- 5.2

25.3 +/- 4.3

21.2 +/- 4.5

20.9 +/- 5.2

Fat mass (%)

25.2 +/- 4.9

38.0 +/- 3.5

28.1 +/- 3.7

34.8 +/- 4.2

Fat free mass (kg) 57.8 +/- 4.6 41.0 +/- 4.4 53.7 +/- 5.1 38.5 +/- 4.4
Fat free mass (%) 74.7 +/- 4.9 62.0 +/- 3.5 71.9 +/- 3.7 65.2 +/- 4.2
BMR (kJ/min) 4.84 +/- 0.45 3.87 +/- 0.38 4.03 +/- 0.46 3.29 +/- 0.42
BMR (kJ/kgbw/min) 0.062 +/- 0.005 0.059 +/- 0.005 0.054 +/- 0.005 0.056 +/- 0.007
BMR (kJ/kgffm/min) 0.084 +/- 0.006 0.095 +/- 0.007 0.075 +/- 0.006 0.086 +/- 0.009
Adjusted Body weight (kJ/min) 4.77 +/- 0.33 3.74 +/- 0.28 4.08 +/- 0.32 3.37 +/- 0.32
Adjusted FFM (kJ/min) 4.68 +/- 0.33 3.78 +/- 0.26 4.14 +/- 0.33 3.35 +/- 0.31
TT3 (umol/l) 1.89 +/- 0.20 1.87 +/- 0.22 1.94 +/- 0.25 1.96 +/- 0.26

TT4 (umol/l)

79.7 +/- 9.2

80.1 +/- 17.4

88.2 +/- 15.9

90.1 +/- 15.8

Other Findings

Italian older volunteers had a significantly lower FFM than middle-aged French volunteers (-7%, P < 0.01).

A negative correlation between BMR and age (men, r = -0.64; women, r = -0.62; both P < 0.0001) was observed:  BMR was significantly lower (P < 0.000001) in Italian elderly volunteers (4.03 +/- 0.46 kJ/min and 3.29 +/- 0.42 kJ/min for men and women, respectively) than in middle-aged French volunteers (4.84 +/- 0.45 kJ/min and 3.87 +/- 0.38 kJ/min for men and women, respectively) even after adjustment for FFM (-12%).

No correlation has been observed between BMR and thyroid hormones both in French and Italian subjects.

Total T4 (TT4) concentrations were lowest in middle-aged population (-10%, P < 0.0001).

A moderate negative correlation has been found with TT4 and red blood cell zinc (r = -0.12, P < 0.02, slope -0.026).

 

Author Conclusion:

The results of this study showed that older subjects participating in the ZENITH study have a lower FFM and BMR than middle-aged subjects.  The results of this study confirm the age-related decline in BMR, which cannot entirely be explained by body composition or thyroid hormones differences.  This study also shows that older individuals have a moderately higher plasma concentration of TT4, suggesting an age-related impairment in the normal mechanisms that regulates energy expenditure and a possible role of zinc.

Funding Source:
University/Hospital: National Institute for food and Nutrition Research (france), INRA, Rowette Research Institute (Scotland), University of Ulster (UK), Universite de Joseph Fourier
Reviewer Comments:

Inclusion/exclusion criteria and recruitment methods not well defined.

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? No
  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? ???
  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? ???
  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.) ???
  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? 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