EAL

FNOA: Assessment of Overweight/Obesity (2012)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To describe the magnitude of the change in appendicular and trunk skinfold thicknesses and circumferences over a 10-year period in relation to the change in total body fat, metabolic parameters and physical activity in men and women.

Inclusion Criteria:

Completed both initial testing between 1984-1991 and follow-up testing five to 12 years later.

Exclusion Criteria:

Did not complete both the initial screening and the follow-up screening
Taking medication that could influence body composition
Had a knee or hip arthroplasty.

Description of Study Protocol:

Recruitment: Reported in an earlier paper
Design: Prospective cohort study
Blinding used: Implied with measurements
Intervention: Not applicable.

Statistical Analysis

Repeated measures of analysis of variance was used to assess change in body composition and anthropometric variables from baseline to follow-up, with adjustment for number of years to follow-up
Comparisons of physical activity between genders at baseline and over time were made using the Kruskal-Wallis test
Linear regression analysis was used to assess the association between anthropometric and whole-body measures of fat and lean mass
Analysis of covariance with adjustment for appropriate covariates was used to assess differences between groups distinguished by physical activity changes.

Data Collection Summary:

Timing of Measurements

A complete set of measurements was taken at baseline and five to 12 years later at follow-up.

Dependent Variables

Total body fat by hydrodensitometry
Skinfold thickness (vertical triceps skinfold, vertical biceps skinfold, subscapular skinfold, suprailiac skinfold, midaxillary skinfold, vertical abdominal skinfold
Circumferences (mid-arm at level of the triceps skinfold, abdominal at the site of the natural waist, hip at the largest circumference of the buttocks, mid-thigh at the level halfway between the top of the patella and the inguinal crease, calf at the largest circumference)
Computerized tomography of the left leg (included to document regional changes in fat and fat-free tissues relative to change in thigh girth)
Glucose, triacylglycerol and total cholesterol drawn after a 12 to 14-hour overnight fast.

Independent Variables

Change in age
Physical activity habits measured by questionnaire.

Description of Actual Data Sample:

Initial N: 141 subjects
Attrition (final N): 129 subjects
- 54 men
- 75 women
Age: 60.4±7.8 years at baseline (range, 46 to 78 years)
Ethnicity: Not reported
Other relevant demographics: Not reported
Anthropometrics: Baseline BMI
- 24.7±3.7kg/m² in women
- 25.1±2.6kg/m² in men.
Location: Boston, Massachusetts.

Summary of Results:

Key Findings

Body weight increased significantly in women (1.1±5.2kg; range, -8.8-19.4kg) over the follow-up period (P<0.05). Fat mass increased significantly in women (1.3±4.4kg; range, -7.0-15.8kg) over the follow-up period (P<0.05) and accounted for the increase in body weight almost entirely.
Body weight did not change significantly in men, however fat mass did increase significantly (1.0±3.2kg; P<0.05)
All skinfold-thickness measures, except those at the subscapular site, declined significantly over the follow-up period in both women and in men (P<0.05 to P<0.001). The sum of all six skinfold-thickness sites also declined significantly, by 33.9mm in women and by 35.2mm in men (P<0.001).
Arm and thigh circumference declined in both men and women (P<0.001). Women showed a greater decline in thigh circumference than men (-5.6%; P<0.02) and men showed a greater decline in arm circumference (-5.2%; P<0.002).
Waist circumference increased significantly in women (4.0±6.8cm; P<0.001), but not in men. Hip circumference decreased significantly in men (-2.7±3.0cm; P<0.002).
Waist-to-thigh and waist-to-arm ratios increased in both genders at follow-up (P<0.001). Waist-to-hip ratio increased significantly in women at follow-up (0.03±0.05cm; P<0.001).
Each skinfold thickness and circumference measurement was significantly associated with total-body fat mass and percentage body fat at both the baseline and the follow-up in both men and women
Considering all anthropometric measures, the changes in waist and hip circumferences were the best predictors of the change in fat mass in women, explaining 53% and 63% of the variance, respectively. Change in waist and hip circumference explained 42% and 40% of the variance in men, respectively.
Although waist-to-hip ratio was significantly associated with the change in fat mass, it explained 15% of the variance.

Other Findings

Plasma triacylglycerol was associated with waist circumference at baseline (R=0.43, P<0.001) and at follow-up (R=0.33, P<0.001), but not with the other girths, skinfold thicknesses, fat mass or percentage fat
Plasma glucose was associated with waist circumference at baseline (R=0.22, P<0.018) and at follow-up (R=0.27, P<0.02), but the change in plasma glucose was not associated with the change in any of the body-composition variables
Total cholesterol was both associated with any whole-body or regional body-composition measures of fat mass at either baseline or follow-up
Percentage body fat was inversely related to physical activity in men only at follow-up (R= -0.37, P<0.007).

Author Conclusion:

The results of the present study show that substantial subcutaneous fat losses (-17.2%) mask the increase in total body fat mass (7.2%) with advancing age
Skinfold thickness cannot be used to assess changes in body fat mass because of age-related fat redistribution
Higher levels of physical activity can attenuate the decline in appendicular lean tissue expected over 10 years
Waist and thigh girths, rather than skinfold thicknesses, should be considered for use in longitudinal studies in the elderly because the changes in these girths capture increased abdominal adiposity and sarcopenia, respectively.

Funding Source:

Government:

US Department of Agriculture

Reviewer Comments:

Recruitment and methods published in a previous paper and not duplicated.

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?	???
	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.)	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?		???
	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%.)	???
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	???
	4.4.	Were reasons for withdrawals similar across groups?	???
	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?	No
	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.)	No
	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?		Yes
	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?	Yes
	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?	No
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