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 sarcopenic obesity is independently associated with and precedes the onset of Instrumental Activities of Daily Living (IADL) disability in community-dwelling elderly.

Inclusion Criteria:

Subjects had to be

Members of the New Mexico Aging Process Study (NMAPS), an ongoing longitudinal cohort study of aging that began in 1980
60 years old or older
Free of major medical conditions
Living independently in the Albuquerque, New Mexico area.

Exclusion Criteria:

Subjects were excluded if they had significant illness that would preclude their ability to participate in a long-term longitudinal study.

Description of Study Protocol:

Recruitment

Participants of the NMAPS study, a dynamic cohort in which dropouts and deaths are replaced annually to keep the active cohort at an average of approximately 400 subjects per year.

Design

Longitudinal prospective cohort study. Participants were seen annually for a thorough examination that included a blood draw, measures of body composition, measures of functional and cognitive status and nutritional assessment.

Blinding used

Implied with measurements

Intervention

Not applicable

Statistical Analysis

Body mass index (BMI), waist/hip circumference ratio (WHR) and ratio of the subscapular to the sum of the lateral calf and thigh skinfolds (SFP) were calculated as indices of body fatness and fat distribution. Anthropometric estimates of mid-arm and calf muscle areas were calculated.
Study population was divided into age groups 60 to 70 years, 71 to 80 and >80 years
Analysis of variance was used to detect statistically significant (<0.05) differences between the age groups for mean values of the anthropometric and body composition variables in each sex
Cox proportional hazards analysis was used to determine the association of baseline sarcopenic obesity with onset of IADL disability
Body composition variables were also regressed on age while controlling for measures of body size and dietary intake
Age-adjusted correlations were calculated with anthropometric variables.

Data Collection Summary:

Timing of Measurements

Measurements of body composition began in 1991 and the data in this paper was collected during 1992 and 1993.

Dependent Variables

Instrumental Activities of Daily Living (IADL) disability
Incident disability was defined as a loss of two or more points from baseline score on the IADL.

Independent Variables

Whole body composition was measured by X-ray absorptiometry
Anthropometry measurements were taken using standardized methods including use of a beam balance, wall-mounted stadiometer, steel or flexible fiberglass tape, Holtain calipers and sliding caliper
Regional body composition was estimated from DXA scans
Dietary intake was estimated using a modified standard food frequency questionnaire.

Control Variables

Age
Sex
Self-reported physical activity
Morbidity.

Description of Actual Data Sample:

Initial N: 536 subjects had at least two IADL scores between 1993 and 2001
Attrition (final N): 451 in final analysis. 68 were excluded since their baseline score was less than eight and another 17 were excluded since they had no body composition data in the year they had their first IADL score measured.
Age: 60-95 years
Ethnicity:
- 90% non-Hispanic White
- 8% Hispanic
- 2% non-White (Black, Asian or American Indian)
Other relevant demographics: At time of body composition measurements:
- 16% women and 21% of men had cardiovascular disease
- 19-20% of the participants had hypertension
- 40-48% of the participants had osteoarthritis
Anthropometrics
Location: Albuquerque, New Mexico.

Summary of Results:

Key Findings

26 subjects were sarcopenic obese, 82 were sarcopenic non-obese, 146 were non-sarcopenic obese, and 197 were non-sarcopenic non-obese
During the eight-year follow-up period, 77 subjects (17%) experienced a drop in functional status
Subjects with sarcopenic obesity at baseline were two to three times more likely to report onset of IADL disability during follow-up than lean sarcopenic or non-sarcopenic obese subjects and those with normal body composition (P<0.03)
The relative risk for incident disability in sarcopenic obese subjects was 2.63 (95% confidence interval: 1.19 to 5.85), adjusting for age, sex, physical activity level, length of follow-up and prevalent morbidity.

Author Conclusion:

In summary, sarcopenic obesity in old age is more strongly associated with IADL disability than either sarcopenia or obesity per se in the NMAPS. These findings need to be replicated in other, larger cohort studies with suitable data for body composition, IADL disability and functional status. Further research is needed on the etiology of sarcopenic obesity as a late-life body composition disorder that is most strongly predictive of disability in old age.

Funding Source:

Government:

NIH

Reviewer Comments:

Low dropout rate due to dynamic cohort. Authors note the following limitations:

Study cohort was small and sarcopenic obesity was rare, limiting the statistical power to detect associations
Small sample size also limited the ability to analyze potentially confounding associations with incident morbidity
Method used to define sarcopenic obesity was relatively arbitrary
NMAPS cohort is not strictly population-based, it is composed of volunteers and the entry criteria exclude those with serious diseases, thus our results may not be generalizable to a broader population.

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?	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?		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?		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?	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?		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