FNOA: Assessment of Overweight/Obesity (2012)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

To examine longitudinally the association between waist circumference and self-reported disability among older adults.

Inclusion Criteria:
  • Men and women
  • 60 years of older
  • Non-institutionalized Spanish
  • Selected through probabilistic multistage cluster sampling.
Exclusion Criteria:
  • Subjects who could not be interviewed after 10 failed home visits
  • Subjects who were incapacitated, institutionalized or refused to participate further.
Description of Study Protocol:

Recruitment

Subjects were selected through probabilistic multistage cluster sampling and gave informed consent or it was obtained from cohabiting next-of-kin.

Design

Prospective cohort study

Blinding used

Not applicable

Intervention

Not applicable

Statistical Analysis

  • The association between WC and disability at baseline was summarized using odds ratios (ORs) obtained from logistic regression
  • To investigate the association between WC and the risk of disability two years later in life, a cross-sectional analysis was used 
  • Statistical significance was set at P<0.05 (two tailed) 
  • Analysis was performed separately for men and women using SAS software, version 8.2.
Data Collection Summary:

Timing of Measurements

Data collected at baseline related to anthropometric and disability estimates was followed in two years by telephone interviews in order to determine the progression of disabilities over time. 

Dependent Variables

  • Mobility
  • Agility
  • Restriction of daily activities (RDA)
  • Instrumental activities of daily living (IADLs)
  • Basic self-care activities.

Independent Variables

Baseline information from personal interviews which included measurement of waist circumference (WC), weight and height.

Control Variables

  • Age
  • Education
  • Tobacco use
  • Alcohol consumption
  • Physical activity
  • BMI
  • Chronic disease
  • Cognitive function.

 

Description of Actual Data Sample:
  • Initial N: 4,008
    • 1,739 males
    • 2,269 females
  • Attrition (final N): 3,235
    • 1,411 men
    • 1,824 women
  • Age: 60 years or older 
  • Ethnicity: Not reported
  • Other relevant demographics: Subjects did not differ significantly in sociodemographic or lifestyle characteristics
  • Anthropometrics: Not applicable
  • Location: Spain.

 

Summary of Results:

Key Findings

  • Among persons reporting no disability at baseline, WC predicted disability two years later 
  • After adjustment for age, education, tobacco use, alcohol consumption, and physical activity, men in the highest waist circumference quintile had 2.17 (95% confidence interval, 1.15 to 4.09) times more risk of mobility disability and 4.77 (95% confidence interval, 2.50 to 9.13) times more risk of agility disability than those in the lowest quintile.
  • Additional adjustment for BMI, chronic diseases, and cognitive function led to only a slight reduction in this association
  • Results were similar for women.
Table 1  Adjusted Odds Ratio of Disability at Follow-up
According to WC Quintiles in Men
  Quintile 2 Quintile 3 Quintile 4 Quintile 5
Mobility

0.86
(0.42 to 1.76)

1.24 (0.63 to 2.43)

1.15 (0.60 to2.19) 

2.17 (1.15 to4.09)* 

Agility

1.03
(0.53 to 2.03)

0.92 (0.47 to 1.83) 

1.62 (0.86 to 3.04) 

4.77
(2.50 to 9.13)+ 

RDA

0.60
(0.31 to 1.16) 

0.48 ((0.25 to0.94)**

0.93 (0.51 to 1.69) 

0.92 (0.50 to1.70)

 *P<0.05,   +P<0.001, **P<0.01 

Table 2   Adjusted Odds Ratio of Disability at Follow-up
According to WC Quintiles in Women

  Quintile 2 Quintile 3  Quintile 4  Quintile 5 
Mobility 

1.11
(0.63 to1.95) 

1.18
(0.67 to 2.08) 

1.53
(0.87 to 2.69) 

1.81
(1.02 to 3.20)* 

Agility

1.00
(1.02 to 3.90)* 

2.06
(1.06 to 4.00)* 

2.25
(1.15 to 4.39)* 

5.21
(2.58 to 10.5)+ 

RDA

0.74
(0.43 to1.25) 

0.88
(0.52 to 1.48) 

0.83
(0.50 to 1.38)

1.36
(0.81 to 2.26) 

Information about Quintile 1 was referred to as appearing in an earlier article and for the purposes of these tables given an Odds Ratio of 1 (low): Granciani A, Banegas JR, et al, Prevalence of disability and associated social and health related factors among the elderly in Spain: a population-based study. Maturitas. 2004; 48: 381-392.   

Other Findings 

  • No statistically significant association was observed between WC and restriction of daily living, limitation in instrumental activities of daily living and limitation in bathing or in dressing in either men or women
  • The association between WC and disability was independent of BMI.
Author Conclusion:

WC predicts mobility and agility disability in old age. Avoidance of the highest values of WC might decrease the risk of disability in older adults. The fact that the association between WC and disability was independent of BMI provides a new reason for measuring WC in addition to BMI in older adults as part of routine clinical practice.

 

Funding Source:
Government: Health Research Fund of Spain
Industry:
AstraZeneca in Spain, ISCIII
Pharmaceutical/Dietary Supplement Company:
Reviewer Comments:

Cohort was representative of the non-institutionalized Spanish population aged 60 and older, and found an association between waist circumference and disability over a follow-up of only two years.

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.) 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? Yes
  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? N/A
  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? 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? 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