EAL

FNOA: Assessment of Overweight/Obesity (2012)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

There is little information about differences in body composition with aging, especially in those older than 65 years. As the proportion of the elderly is expected to nearly double during the next few decades, this information is needed to better plan for their health care. The purpose of this study was to test for differences between age groups and changes in body composition.

Inclusion Criteria:

The subjects for this study were participants in the New Mexico Aging Process Study, a longitudinal study of nutrition and aging begun in 1979
The subjects included men and women who were distributed into three age groups:
- 60 to 70 years
- 71 to 80 years
- Older than 80 years.

Exclusion Criteria:

Persons who had:

Cancer (other than skin) within the last 5 years
Recent myocardial infarction
Chronic obstructive pulmonary disease
Significant medications used to treat cancer, cardiac or respiratory diseases or psychosis.

Description of Study Protocol:

Recruitment

The subjects for the study were participants in the New Mexico Aging Process Study, a longitudinal study of nutrition and aging that started in 1979.

Design

Cross-sectional study.

Blinding Used

Implied with measurements.

Statistical Analysis

Body mass index (BMI), waist/hip circumference ratio (WHR) and the ratio of subscapular to the sum of the lateral calf and thigh skinfolds were calculated as indices of body fatness and fat distribution
Anthropometic estimates of midarm and calf muscle areas were calculated using an appropriate formula
Two approaches were used to examine age differences in anthropometric and body composition variables:
- Analysis of variance was used to detect statistically significant (P<0.05) differences between the age groups for mean values of the anthropometric and body composition variables in each sex
- Body composition variables were regressed on age while controlling for measures of body size and dietary intake.

Data Collection Summary:

Timing of Measurements

The data presented in the study were collected during 1992 and 1993.

Dependent Variables

Fat-free mass (FFM), body cell mass (BCM) and appendicular skeletal muscle (ASM)
Anthropometric indices, muscle mass (MM) and waist/hip ratio (WHR).

Independent Variables

Age groupings:

60 to 70 years
71 to 80 years
Older than 80 years.

Control Variables

Knee height
Fat-free mass
Total body fat.

Description of Actual Data Sample:

Initial N: 128 males, 188 females
Attrition (final N): Seven participants refused to undergo a DEXA scan. Estimates of body fluid volume were obtained only for 187 participants due to time lapse. Therefore, the number of participants differed depending on the variables measured:
- Data from 128 men and 188 women were used to calculate the distribution of anthropometric and body composition variables
- Data from 126 men and 181 women were used in the regression of body composition variables on age in each sex and for the partial correlations between anthropometric and body composition variables adjusting for age
Age: Both men and women ranged from 60 to older than 80 years
Ethnicity: 96% of the participants were non-Hispanic whites while 4% claimed Hispanic origin
Anthropometrics: There were no significant differences in weight or stature between the males in the three age groups or between the females in similar age groupings
Location: The participants resided mostly in the area of Albuquerque, New Mexico.

Summary of Results:

Key Findings

Fat-free mass (FFM), body cell mass (BCM) and appendicular skeletal (ASM) decreased with age in both sexes
ASM decreased relative to FFM in both men and women while BCM decreased relative to FFM in women only
Total fat mass and percent body fat decreased with age in the women but not in the men
Body fat distribution did not appear to change with age
Anthropometric indices, muscle area and waist/hip ratio had low correlation with muscle mass and fat distribution.

Significant Anthropometric and Body Composition Variables in Men and Women

Variables	60 to 70 Years Old	71 to 80 Years Old	Older Than 80 Years
Men
Fat-free mass (kg)*	58.2±4.7	55.4±6.3	53.4±6.1
ASM (kg)*	24.6±2.3	22.9±3.1	21.7±3.0
BCM (kg)*	32.7±1.4	32.6±4.4	29.9±4.0
Women
Fat-free mass (kg)*	40.0±3.4	37.7±3.8	37.3±3.2
ASM (kg)*	15.8±1.6	14.6±1.8	14.2±1.7
BCM (kg)*	24.0±3.2	21.7±3.2	19.9±2.7

*Significant (P<0.05) group differences by Scheffe Test.

Author Conclusion:

Significant age differences exist in the body composition of elderly men and women between 60 and 95 years of age. These differences are interpretable as age-related changes in body composition only insofar as they are not the result of birth cohort differences, secular trends or selective survival.
Long-term longitudinal studies using appropriate technology are needed to quantify actual changes with age. Accepting these limitations our data suggest that trends observed in studies of younger samples continue in relatively active elderly people into the ninth decade of life.
"Sarcopenia" or muscle loss continues to occur into old age, and may have significant impacts on physical function and health status. These differences may be the loss of body fat and the changing composition of the fat free mass with age in our elderly women.
Further study needs to be focused on effect of aging in other racial and ethnic groups and the mechanisms underlying changes with age in body composition.

Funding Source:

Government:

National Institutes of Health

Reviewer Comments:

Authors note the following:

Age differences in men should be interpreted with greater caution than those in the women due to the smaller numbers of men in the study
Findings presented are based on data for the New Mexico Aging Process Study cohort, which is predominantly white, and enjoy better than average health, income, education, and probably dietary intake and physical activity, and may not be generalized to other ethnic or racial groups.

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)	???
	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?		No
	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?	No
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.)	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?	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.)	Yes
	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?	Yes
	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.)	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?		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?	N/A
	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?	N/A
	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?		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