EAL

FNOA: Assessment of Overweight/Obesity (2012)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To determine whether sarcopenia is a progressive process, particularly after the age of 60, in healthy, independently living men and women who may not manifest weight loss.

Inclusion Criteria:

170 subjects over age 60 from a primary recruitment pool for an ongoing study at the Body Composition Unit of the New York Obesity Research Center who were initially tested between 1986 and 1994.

Exclusion Criteria:

Persons who were not initially tested as part of the Body Composition Unit of the New York Obesity Research Center.

Description of Study Protocol:

Recruitment

170 subjects were contacted from a primary recruitment pool for an ongoing study at the Body Composition Unit of the New York Obesity Research Center. 100 agreed to return for evaluation but 70 subjects were unwilling to participate or were excluded for health reasons.

Design

Prospective cohort study.

Blinding Used

Implied with measurements.

Statistical Analysis

The statistical significance of the longitudinal changes in total appendicular skeletal muscle mass was tested within each gender using paired T-tests
Pearson correlation coefficients were used to quantify bivariate relationships between changes in muscle mass and corresponding changes in other lean body components
Data were analyzed using SAS statistical software version 6.12 (SAS Institute, Cary, NC).

Data Collection Summary:

Timing of Measurements

Longitudinal changes in skeletal muscle mass, lean body compartments and total body fat were investigated in subjects with a mean follow-up time of 4.7±2.3 years.

Dependent Variables

Skeletal muscle mass was quantified by using regional DEXA-measured lean soft tissue
Fat-free body mass was calculated as the difference between fat measured by DEXA and body weight
Body cell mass was calculated using a four-pi whole body counter to measure the amount of each subject's radioactive potassium
Total body water was based on the amount of radioactivity obtained in a blood sample taken after a subject received a sample of radioactive water.

Independent Variables

Weight.

Control Variables

Age
Gender
Estrogen replacement therapy.

Description of Actual Data Sample:

Initial N: 1,449 subjects in the original cross-sectional study; 261 of these subjects were over age 60 and were invited for follow-up evaluation. 100 subjects agreed to participate in this study. 29 were men and 71 were women.
Attrition (final N): 78 subjects (54 women and 24 men) were included in the statistical analysis
Age: Mean age:
- At baseline,70.2 years (women); 72.9 years (men)
- At follow-up, 74.8 years(women); 77.8 years (men)
Anthropometrics: Men and women were similar in age at baseline and follow-up. Men were taller and heavier than women but there were no significant gender differences in body mass index.
Location: New York, New York.

Summary of Results:

Key Findings

Total appendicular skeletal muscle mass (TSM) decreased in men (-0.8±1.2kg, P=0.002), consisting of leg skeletal muscle (LSM) loss (-0.7±0.8kg, P=0.001) and a trend toward loss of arm skeletal muscle (-0.2±0.4kg, P=0.06)
In women, TSM mass decreased (-0.4±1.2kg, P=0.006) and consisted of LSM loss (-0.3±0.8kg, P=0.005) and a tendency for a loss of ASM (-0.1±0.6kg, P=0.20)
Multiple regression modeling indicates greater rates of LSM loss in men
Body weight in men at follow-up did not change significantly (-0.5±3.0kg, P=0.44) and fat mass increased (+1.2±2.4kg, P=0.03)
Body weight and fat mass in women were non-significantly reduced.

Significant Results of Longitudinal Body Composition Studies in Men and Women
	Baseline, kg	Follow-up, kg	Change, kg per Year	*P, Change**	P, Gender**
Fat-free body (men)	56.2±8.0	54.9±7.5	-0.3±0.80	0.002	0.002
Fat (men)	15.4±6.7	16.6±7.5	0.3±0.5	0.03	0.003
Appendicular muscle (AM) (men)	24.9±4.3	24.1±4.1	-0.2±0.5	0.002	0.08
AM (women)	16.4±2.8	15.9±2.2	-0.1±0.4	0.01

Author Conclusion:

Weight stability in older individuals does not imply body composition stability. The finding of significant muscle loss in what presents as healthier-than-normal elderly adults, while maintaining weight stability, exposes sarcopenia as a silent progressive phenomenon similar perhaps to osteoporosis.

Although the current study cannot directly attest to the consequences of observed skeletal muscle changes, the loss of leg skeletal muscle mass and reductions in muscle strength may have implications for overall mobility and physical function.

Funding Source:

Government:

NIH

Reviewer Comments:

Authors note the following limitations:

Study population is limited in size and does not represent a random sample of older individuals but rather a convenience sample of healthy survivors. Subjects with large weight fluctuations were excluded, so findings cannot be considered representative of the aging population in general.
Lack of information on daily physical activity at both measurement points prevents us from investigating if a portion of the individual variation was accounted for by variations in activity
Our ability to accurately detect small compartmental changes over time was limited.

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?	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.)	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?	N/A
	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?		???
	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?	N/A
	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?	???
	7.5.	Was the measurement of effect at an appropriate level of precision?	???
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	No
	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