EAL

FNOA: Assessment of Overweight/Obesity (2012)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To evaluate the association of muscular strength and functional limitations with body fat or muscle mass, testing the contribution of each of these components of body composition to disability in a sample of community-dwelling elderly women at the high end of the functional spectrum.

Inclusion Criteria:

Female
Community-dwelling
Weight-stable
Able to walk 800m without resting
Free of cognitive impairment
Study group aged 67 years to 78 years (with a reference group of pre-menopausal women aged 20 years to 50 years included).

Exclusion Criteria:

Male
Institutionalized
Weight fluctuation of five kg or more over the six months prior to recruitment
Not able to walk 800m without difficulty
Cognitive impairment present as measured by a Mini-Mental Status Examination score higher than 24
Participation in regular physical exercise more than once per week during the study period.

Description of Study Protocol:

Recruitment

Study subjects were recruited from the lists of 11 general practitioners in Verona, Italy. A group of 120 pre-menopausal healthy women, aged 20 years to 50 years, was recruited as a young reference group. This group consisted of nurses, dietitians, medical students and residents working in the Geriatric Department of the University of Verona.

Design

Cross-sectional study.

Blinding Used

Implied with measurements.

Statistical Analysis

The differences between observed frequencies of subjects reporting functional limitation according to BMI categories, percentage body fat and relative muscle mass quintiles, sarcopenia/obesity groups, ASM/h² (appendicular skeletal muscle mass adjusted by stature index) and SMI (skeletal muscle index) classes were tested using chi-square analysis for trend
Differences between normal-weight and obese women as well as between subjects in the first and fifth body fat and relative muscle mass quintiles, between difference sarcopenic/obesity classes and between subjects classified as normal or class II sarcopenic, according to the Baumgartner and Janssen index, were tested using Student's T-test for unpaired data
Odds ratios predicting functional limitations, based on different body composition measurements and indexes were obtained from logistic regression models after controlling for potential covariates
Comparisons between the mean values of isometric leg strength in different groups of patients were made using Student's T-test for unpaired data.

Data Collection Summary:

Timing of Measurements

Subjects completed a physical examination following recruitment.

Dependent Variables

Muscular strength: Isometric strength of the dominant knee extensors was tested by a Spark Handheld Dynamometer
Functional limitation: Assessed according to Langlois using three scales: ADL scale, three Rosow and Breslau physical function items and IADL scale.

Independent Variables

Body fat: Dual-energy X-ray absorptiometry
Muscle mass: Dual-energy X-ray absorptiometry; predictive equation of Kim, used to compute the total body skeletal mass from appendicular lean soft tissue mass
Measured body weight, measured height and calculated BMI.

Control Variables

Age
Presence of chronic health conditions.

Description of Actual Data Sample:

Initial N: 167 women (a group of 120 pre-menopausal healthy women represented a young reference group)
Attrition (final N): 167 women
Age: 67 years to 78 years
Ethnicity: Italian
Other relevant demographics: Not reported
Anthropometrics: Mean BMI, 26.1±3.8kg/m² (range, 18.1kg to 35.1kg/m²)
Location: Verona, Italy.

Summary of Results:

Key Findings

Body composition and disability: Percentage of elderly women reporting functional limitation based on BMI category, percentage of body fat quintile, relative muscle mass quintile, sarcopenic obesity grouping, ASM/h² and SMI classes

	Characteristic (N=167)	Percentage Reporting Functional Limitation (N)
BMI Category^a	20-24.9kg/m²	38.0% (27)
	25-29.9kg/m²	40.8% (28)
	>30kg/m^2b	63.0% (17)
Percentage Body Fat Quintile^a	1	41.2% (14)
	2	27.3% (9)
	3	44.1% (15)
	4	34.3% (12)
	5^c	68.8% (22)
Relative Muscle Mass Quintile	1	54.5% (18)
	2	32.4% (11)
	3	32.4% (11)
	4	55.9% (19)
	5	41.2% (14)
Sarcopenia/Obesity Group	Normal body fat and muscle mass	33.9% (19)
	High body fat only^c	52.2% (24)
	Low muscle mass only	42.2% (19)
	High body fat and low muscle mass	47.6% (10)
ASM/h² Class (appendicular skeletal muscle mass adjusted by stature)	Normal	50.0% (33)
	Class I sarcopenia	37.5% (30)
	Class II sarcopenia	47.6% (10)
SMI (skeletal muscle mass index) class^d	Normal SMI	25.0% (4)
	Class I sarcopenia	35.5% (22)
	Class II sarcopenia^c	52.8% (47)

a: P-value for trend <0.05
b: P<0.01 (compared to normal weight)
c: P<0.05 (compared to the normal class or first quintile)
d: P for trend <0.01.

OR from logistic regression models predicting functional limitation, based on BMI category, percentage body fat quintile, relative muscle mass quintile, sarcopenic obesity group, ASM/h² and SMI classes

	Characteristic (N=167)	OR (95% CI)
BMI Category	20-24.9 kg/m²	1.00
	25-29.9 kg/m²	1.01 (0.48-2.11)
	>30 kg/m²	4.56 (1.51-13.77)
Percentage Body Fat Quintile	1	1.00
	2	0.47 (0.15-1.43)
	3	0.80 (0.27-2.36)
	4	0.79 (0.27-2.28)
	5	3.07 (1.02-9.25)
Relative Muscle Mass Quintile	1	1.91 (0.66-5.53)
	2	0.76 (0.26-2.24)
	3	0.67 (0.22-2.02)
	4	2.30 (0.79-6.66)
	5	1.00
Sarcopenia/Obesity Group	Normal body fat and muscle mass	1.00
	High body fat only	3.06 (1.25-7.47)
	Low muscle mass only	1.83 (0.75-4.47)
	High body fat and low muscle mass	2.16 (0.73-6.42)
ASM/h² Class	Normal ASM/h2	1.00
	Class I sarcopenia	0.54 (0.26-1.11)
	Class II sarcopenia	0.98 (0.35-2.78)
SMI Class	Normal SMI	1.00
	Class I sarcopenia	1.57 (0.39-6.33)
	Class II sarcopenia	3.86 (1.01-14.87)

Adjusted for age, heart disease, hypertension, diabetes and arthritis.

Author Conclusion:

High body fat and high BMI values are associated with a greater likelihood of functional limitation in a population of elderly women at the high end of the functional spectrum
Women in the highest quintile of body fat or with BMI higher than 30kg/m² had a three to four times increased risk of functional impairment
Isometric leg strength was not related to fat mass
No relation between indexes of sarcopenia expressing the absolute amount of body skeletal muscle mass and disability was noted
Obesity is independently associated with functional limitation and disability in the elderly
Our findings do not support a relation between functional limitations and overweight.

Funding Source:

Government:

MURST Project Grant (Italy)

Reviewer Comments:

Relatively small sample
Limited to women
Limited to community-dwelling individuals with low levels of functional impairment
No performance-based measured of physical function
Cross-sectional study, causal relationship can only be inferred.

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?		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%.)	N/A
	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?	Yes
	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?	No
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