EAL

FNOA: Assessment of Overweight/Obesity (2012)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To assess the association between various body composition indices and functional limitations in a representative sample of US men and women aged 70 and older.

Inclusion Criteria:

Men and women aged 70 and older who participated in the 1994 to 1998 National Health and Nutrition Examination Survey III (NHANES III) and who had anthropometric data collected at Mobile Examination Centers (MEC), which were part of NHANES III.

Exclusion Criteria:

Persons for whom MEC data was missing
Persons in an "other" ethnic category, which included those who were not non-Hispanic whites, non-Hispanic blacks or Mexican Americans.

Description of Study Protocol:

Recruitment: According to the guidelines for NHANES III
Design: Cross-sectional, population-representative sample
Statistical analysis: All analyses used survey data analysis software, Version 7.5 (Research Triangle Institute, Research Triangle Park, NC) and included Pearson product moment correlations, logistic regression models and the Zhang equation.

Data Collection Summary:

Timing of Measurements

Timing and measurements of body composition were made during a MEC examination following NHANES III guidelines
Data collected during 1988 and 1994.

Dependent Variables

Functional limitations were assessed by individual reports of mobility related to walking difficulties, difficulty stooping, crouching, kneeling or carrying a heavy (at least 10 pounds) object. The reports were coded to quantitate individual difficulties and for use in statistical analysis.

Independent Variables

BMI
Muscle mass and percentage of body fat were assessed using predictive equations.

Control Variables

Age
Education
Ethnicity
Chronic illness or disease
Smoking history
Estrogen replacement therapy
Physical activity.

Description of Actual Data Sample:

Initial N: 1,391 males and 1,526 females
Attrition (final N): 1,391 males and 1,526 females
Age: 70 and older
Ethnicity: Non-Hispanic whites, non-Hispanic blacks, Mexican Americans
Location: United States.

Summary of Results:

Key Findings

Percentage of Subjects Reporting Functional Limitations Based on Body Mass Index

Body Mass Index	Women	Men
<18.5	53.3±10.5	36.1±10
18.5-24.9	28.3±2.1	22±2.3
25-29.9	37.6±2.7	23.3±2.4
30-34.9	46.1±4	23.4±4.2
≥35	67.0±6.6	34.2±5.9

Other Findings

Women in the highest quintile for percentage of body fat and women with a BMI of 30 or greater were two times more likely to report functional limitations than women in the comparison groups
Similar but weaker relationships were found among men
Men in the highest quintile for body fat and men with a BMI of 35 or greater were 1.5 times more likely to report limitations
Low muscle mass (sarcopenia) and sarcopenia in combination with high percentage of body fat (sarcopenic obesity) were not associated with a greater likelihood of reporting functional limitations.

Author Conclusion:

Prevention of excessive accumulation of body fat and maintenance of BMI in the normal range may reduce the likelihood of functional limitations in old age.

Funding Source:

Government:

CDC

Reviewer Comments:

Large, nationally representative sample
Authors note that persons aged 60 and older, African-Americans and Mexican Americans were oversampled.

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?		Yes
	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?	Yes
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?	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?		???
	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.)	N/A
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	???
	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?	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