FNOA: Assessment of Overweight/Obesity (2012)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

To investigate body composition over time in healthy, ambulatory, elderly African American women and investigate the hypothesis that there are ongoing reductions in skeletal muscle (SM) and increases in total adipose tissue (TAT), subcutaneous adipose tissue (SAT) and adipose tissue visible within the muscle area (IMAT).

Inclusion Criteria:
  • Independent, community-dwelling African American women
  • Age older than 65 years
  • Ambulatory
  • Non-exercisers
  • Non-smoking
  • Stable body weight (change of 3kg or less over the previous three years).
Exclusion Criteria:
  • Those with untreated diabetes mellitus
  • Those with malignant or catabolic conditions
  • Those missing a limb
  • Those who have undergone joint replacement
  • Those taking estrogen replacement therapy or other medications that could influence body composition.
Description of Study Protocol:

Recruitment

Participants were recruited through advertisements in newspapers and flyers posted in the local community. 

Design

Prospective cohort study. 

Blinding Used

Implied with measurements.

Statistical Analysis

  • Longitudinal changes in each body composition component, physical activity and function, and food intake were tested by using paired T-tests
  • Pearson's correlation coefficients were used to quantify bivariate correlations between baseline body composition components obtained with the use of MRI and DXA
  • The relation between changes over time in each body composition measurement and its baseline value was tested by using regression analysis in which the observed change was set as the dependent variable and its baseline value was set as an independent variable
  • In all analyses, a two-tailed α level of 0.05 was used.

 

Data Collection Summary:

Timing of Measurements

  • Data was collected at baseline and follow-up. Mean follow-up time was 2.04 years ± 0.6 years.
  • During baseline, each subject completed a medical examination that included screening blood tests after an overnight fast. Body weight and height were obtained. SAT, TAT and IMAT data were collected using whole-body multi-slice MRI. Total bone mineral content, total body fat and fat-free mass (calculated) were measured using a whole-body dual-energy X-ray absorptiometry scanner.

Dependent Variables

  • Total body skeletal mass (SM) as measured using a whole-body multi-slice MRI
  • Visceral adipose tissue (VAT) as measured using a whole-body multi-slice MRI
  • Subcutaneous adipose tissue (SAT) as measured using a whole-body multi-slice MRI
  • Intermuscular adipose tissue (IMAT) as measured using a whole-body multi-slice MRI
  • Fat-free mass as calculated using total-body bone mineral content (TBBMC), which was measured using a whole-body dual-energy X-ray absorptiometry scanner
  • Total body fat (TBF) as measured using a whole-body dual-energy X-ray absorptiometry scanner
  • Physical function was tested at baseline and follow-up. Muscle strength, lower-extremity function, gait and balance were evaluated.
  • Usual dietary intake was estimated using a self-administered food frequency questionnaire at baseline and follow-up
  • Blood samples were drawn after an overnight fast and analyzed for triacylglycerols, total and DHL cholesterol and glucose.

Independent Variables

Passage of time as measured in months and  years. 

Description of Actual Data Sample:
  • Initial N: Baseline data was collected on 43 women. 31 returned for follow-up evaluation. Of the 31 who returned, five were excluded from the final analysis.
  • Attrition (final N): Final N=25. The study lost 18 participants, or 42% of the original participants.
  • Age: Older than 65 years at baseline. Mean age at baseline was 75.5±5.1 years.
  • Ethnicity: African American
  • Other relevant demographics: No data on SES or education level was provided
  • Anthropometrics: At baseline, the BMI of participants was 27.0±4.0
  • Location: New York City, NY.
Summary of Results:

Key Findings

  • Participants who returned for follow-up evaluation had no significant differences in age, height, weight, FFM or fat mass measurements obtained by DXA
  • Significant losses occurred in total SM measurements (obtained by MRI). Of the total sample of 26 women who completed the study, 21 (81%) had a decrease or no change in SM from baseline to follow-up.
  • There was an increase in VAT over the two-year period. There was no significant change in SAT. IMAT increased significantly.
  • TBBMC decreased significantly over the two-year period. No significant changes were observed in total cholesterol, triacylglycerols or glucose. The observed changes in VAT and IMAT did not correlate significantly with changes in the metabolic variables measured.
  • No significant differences in physical function or diet with noted between baseline and follow-up.

Results of Longitudinal Body Composition Studies in 26 Subjects1

  Baseline Change P2 Change3 P4
Body weight (kg) 66.2±10.25 0.24±2.4 0.62 0.28±1.5 0.69
MRI (kg)
SM

18.6±2.40

-0.72±0.72

0.0016 

-0.37±0.4 

0.002 

TAT

26.8±7.97

0.28±1.99

0.45

0.17±1.0

0.37

SAT

24.0±7.53

-0.02±1.64

0.96 

0.00±0.2

0.99 

VAT

1.87±1.01

0.19±0.35

0.011

0.10±0.2 

0.016
IMAT

1.08±0.42

0.14±0.17

0.0016

0.07±0.1

0.001 

DXA (kg)
FFM

41.1±4.57

0.03±1.18

0.89

0.07±0.8

0.42

ASM

4.25±0.54

0.06±0.30

0.33

0.05±0.2 

0.20

LSM

13.1±1.73

-0.30±0.66 

0.03

-0.11±0.3

0.08

TBF

24.8±7.73

0.09±2.3

0.84

0.13±1.3

0.61

TBBMC

2.18±0.29

-0.03±0.06

0.03

-0.01±0.03

0.003 

1SM, skeletal muscle; TAT, total adipose tissue; SAT, subcutaneous adipose tissue; VAT, visceral adipose tissue; IMAT, intermuscular adipose tissue, FFM, fat-free mass; ASM, arm skeletal muscle; LSM, leg skeletal muscle; TBF, total body fat; TBMC, total-body bone mineral content; MRI, magnetic resonance imaging; DXA, dual-energy X-ray absorptiometry.

²For the test of change between baseline and follow-up.

³Changes are per year and do not equal absolute change because the follow-up period varied between one and three years (19 to 35 months).

4 For the test of change year.

5 Mean ± SD.

6 Adjusted Bonferroni values for significance within MRI and DXA, P<0.01.

Summary of Physical Function and Dietary Intake at Baseline and Follow-up¹

  Baseline Follow up
Physical function
  Grip strength (kg)    
    Left hand (N=22)

26.8±4.7

24.4±5.3

    Right hand (N=22)

25.4±3.6

25.0±5.3

  Chair stand (N=23)

13.2±4.3

13.1±3.4

  Two-minute walk (N=18)

144.6±23.2

154.8±33.6

Standing balance (s) 

  30cm narrow walk (N=23) 5.2±1.0

5.6±0.9

  20cm narrow walk (N=22)

5.2±1.1

5.8±1.1

  Semitandem stand test (N=24)

28.0±6.9

28.3±5.8

  Tandem stand test (N=23)

25.8±9.5

27.3±7.2

FFQ (N=25)

  Total energy intake (kcal per day)

1126.4±734.0

1326.6±869.4

  Protein (g per day)

47.1±28.9

54.3±47.1

  Carbohydrate (g per day)

157.8±90.8

160.6±83.7

  Fat (g per day)

49.4±35.2

49.6±46.8

  Calcium (mg per day)

433.6±398.5

499.7±406.8

¹All values are mean ± SD. FFQ, food-frequency questionnaire. There was no significant differences between baseline and follow-up values; however, the differences from baseline for the 30cm narrow walk was nearly significant (P=0.06).

 

 

Author Conclusion:

In a sample of independently living, healthy African American women, the findings support the hypothesis that a reduction is SM and increases in IMAT and VAT occur with advancing age, despite no detectable changes in physical functioning or dietary intake.  

Funding Source:
Government: National Institutes of Health
University/Hospital: St. Luke's-Roosevelt Hospital, Kyung Hee University
Reviewer Comments:
  • This reviewer is concerned that 43 women originally enrolled in the study and only 31 completed it, with five subjects lost for a variety of reasons
  • The mean follow-up period was 2.04 years but follow-up varied from 19 to 35 months. This reviewer believes that time difference in follow-up between study participants could result in inaccurate results and that 19 months may not be adequate time for follow-up to observe a change.
  • The study did not take physical activity over time into account. The level of weight-bearing exercise that participants took part in could affect their FFM over time.
  • As was mentioned in the discussion section, the authors do not attempt to account for changes in medical condition that could have occurred over time and could have affected results.
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? Yes
  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? 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? No
  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? No
  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? No
  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? ???
  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? No
  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? No
  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)? No
  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