EAL

FNOA: Assessment of Overweight/Obesity (2012)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To characterize physical function themes based on combinations of tasks (deriving factors or components)
To quantify the correlation between derived factors and body mass index (BMI).

Inclusion Criteria:

Female
BMI more than 22kg/m²
Enrollees in a Medicare managed-risk program
Attended a Geisinger clinic site in rural central and eastern Pennsylvania
Age 65 years or older.

Exclusion Criteria:

BMI 22kg/m² or less
Age less than 65 years
Not community-dwelling
History of severe depression
History of cognitive disability
History of rheumatoid arthritis, Paget's disease of bone or other bone disease
Disability caused by prior trauma.

Description of Study Protocol:

Recruitment

A stratified random sampling scheme was implemented through a nutrition screening program of the Geisinger Health Plan that is administered to all enrollees in a Medicare managed-risk program.

Design

Cross-sectional study.

Blinding used

Implied with measurements.

Statistical Analysis

A factor analysis was used. Varimax rotation of retained factors estimated factor loadings for the purpose of interpretation. Multiple linear regression analysis quantified associations between BMI, while controlling for age, with derived components characterized by specific dimensions of physical function.

Data Collection Summary:

Timing of Measurements

One home visit was conducted after written consent was received from the recruited participant. During the home study, a "mini-mental status" exam was give and a composite set of tasks from the Physical Performance Test (PPT) and The Frailty and Injuries: Cooperative Studies of Intervention Techniques (FICSIT) trials was evaluated for each participant.

Dependent Variables

Quartile rankings for each task evaluated
- Write sentence
- Simulate eating
- Lift book
- Put on and remove a jacket
- Pick up a penny from the floor
- Circle turn
- Walk 50 feet
- Stair climbing
- Accelerated chair stand
- Hand-grip dynamometry (dominant and non-dominant hand)
- Static balance (foot halfway in front of the other, foot totally in front of the other)
- One-legged stance (eyes open, right side; eyes open, left side; eyes closed, right side; eyes closed, left side)
Factors (parsimonious set of thematically meaningful factors)
- Lower-body function
- Upper-body function
- Standing coordination
- Strength.

Independent Variables

Height
Weight
BMI.

Control Variables

Age.

Description of Actual Data Sample:

Initial N: 90 women
Attrition (final N): 88 women (two women were excluded after scoring less than average for the population on the "mini-mental status" exam)
Age: Mean age 71±5 years (no difference noted between BMI groups)
Anthropometrics: Groups were created by categorizing women into three different BMI groups (BMI 22 to less than 27kg/m²; BMI 27 to less than 30kg/m²; BMI 30kg/m² or higher
Location: Rural central and eastern Pennsylvania.

Summary of Results:

Key Findings

Factor analysis:
- The factor analysis produced four factors with latent root values greater than one (factors three and four were considered marginal
- The four factors comprised 59% of the variance in BMI
- The first factor was a measure of lower-body function because the highly loaded tasks included walking 50 feet, static balance, one-legged stance and stair climbing
- The second factor was a measure of upper-body function because the highly loaded tasks included writing a sentence, simulating eating, putting on and removing a jacket, picking up a penny from the floor
- The third (marginal) factor is a measure of coordination in standing with highly loaded tasks including accelerated chair stand and static balance task
- The fourth (marginal) factor is a measure of strength with highly loaded tasks including lifting and hand-grip dynamometry
Summary of regressions of BMI and age on each factor:
- BMI, controlling for age, explained a modest variation in factor scores for lower-body function (5%; P=0.032) and upper body function (14%; P<0.001); but not standing coordination or strength.

Factor	BMI Partial R²	BMI P	Age Partial R²	Age P
Lower-body function	0.050	0.032	0.069	0.012
Upper-body function	0.137	<0.001	0.193	<0.001
Standing coordination	0.029	0.111	0.013	0.281
Strength	--	0.921	0.203	<0.001

Author Conclusion:

Our results indicate that while controlling for age, upper-body function and, to a lesser extent, lower-body function were related to BMI. No evidence was provided to support a link between BMI and strength or BMI and coordination.

Funding Source:

University/Hospital:

Geisinger Medical Center

Reviewer Comments:

A comparison of women in the sampling frame who did not participate in the study was made to those enrolled. No difference was noted in age or average BMI. The two groups did not differ with respect to the self-reported responses on the Nutrition Risk Level II Screen, except for a greater number of non-participants reported a loss of 10 pounds in the last six months.
Authors did not comment on how the cutoff numbers for BMI categories were selected with the exception of the statement that women with a BMI less than 22kg/m² were excluded because of the likelihood of disability secondary to frailty and sarcopenia
The potentially confounding effect of habitual activity level on strength and physical function was not measured or analyzed in this study
Age seemed to play a significant role in the variance in physical function (lower-body function, upper-body function and strength). The authors did demonstrate that BMI explained a modest variation in factors scores after controlling for age.
The sample was taken from a small, rural, geographical area. The results may not be extrapolated to the entire population of elderly women as a whole.

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?		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?	No
	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.)	???
	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?	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?	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)?	No
	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?	Yes
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