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UWL: Association With Outcomes (2009)

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

To describe the distribution of BMI among the elderly in a community and investigate the association of obesity and underweight with selected health conditions and socioeconomic differences in this group.

Inclusion Criteria:

All residents aged 60 years or older in Bambui, Minas Gerais State, Brazil.

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment

The present study analyzes the baseline data of the Bambui Health and Aging Study (BHAS), a population-based cohort study of older adults living in Brazil. All residents aged 60 years or older in Bambui, Minas Gerais State, Brazil were selected for interviews and examination (N=1,742). 

Design

Cross-sectional, descriptive analysis of baseline cohort data.

Statistical Analysis

  • Descriptive statistics were used to fully explore the data
  • One-sample T-test was used for comparisons between means and design-based Pearson chi-square test for proportions
  • Multinomial logistic regression techniques were used to estimate the association of BMI with independent variables.
Data Collection Summary:

Timing of Measurements

At baseline, residents were selected for interviews and examination, which included blood tests, and anthropometric and blood pressure measurements. Interviews, physical measurements and blood tests were conducted from January 1997 to August 1997.

Dependent Variables

  • Weight, height and BMI (obesity was considered to be BMI higher than 30kg/m2, underweight was considered to be BMI less than 20kg/m2)
  • Waist and hip circumferences
  • Blood pressure
  • Blood samples analyzed for plasma glucose, hemoglobin and presence of Trypanosoma cruzi infection.

Independent Variables

  • Sociodemographic characteristics (age, gender, marital status, schooling and monthly income)
  • Lifestyle (current smoking status and physical activity)
  • Self-rated health in the previous six months
  • Health services indicators (doctor visits in the past 12 months and hospitalizations in the past 12 months).

Control Variables

  • Age
  • Sex.
Description of Actual Data Sample:
  • Initial N: 1,742 residents were selected for interviews and examination
  • Attrition (final N): 1,443 (83.1%) of the town's elderly participated
  • Age: 60 years or more
  • Location: Bambui, Minas Gerais State, Brazil.
Summary of Results:

Association of Underweight and Obesity with Health Perception and Health Care Use Selected in the Multivariate Analysis, BHAS, 1997

Variables

Underweight (N)

Underweight

Odds Ratio (95% CI)

Obesity (N)

Obesity

Odds Ratio (95% CI)

Visits to doctor in past 12 months

        

None

40

1.0

19

 1.0
1 41 1.0 (0.6 to 1.6) 36 1.4 (0.8 to 2.6)
2+ 127 1.0 (0.6 to 1.5) 130 1.8 (1.1 to 3.1)
Hospitalizations in past 12 months        
None 144 1.0 146 1.0
1 37 1.4 (0.9 to 2.1) 27 0.8 (0.5 to 2.2)
2+ 27 2.4 (1.4 to 4.2) 12 1.1 (0.6 to 2.2)
Self-rated health in past six months        
Very good or good 40 1.0 39  1.0
Fair 98 1.2 (0.8 to 1.8) 91 1.7 (1.2 to 2.5)
Poor or very poor 91 1.5 (1.0 to 2.4) 55 1.1 (1.1 to 2.8)

Other Findings

  • Mean BMI was 25.0±4.9kg/m2, was higher for women and decreased with age
  • There was a highly statistically significant declining trend in the age- and sex-adjusted prevalence of underweight with increasing income and schooling: Odds ratio of 0.50 (0.31 to 0.82), 0.31 (0.13 to 0.74), and 0.28 (0.12 to 0.66) for monthly family income equal to 2.0 to 3.9, 4.0 to 5.9, and more than six times the Brazilian minimum wage, and odds ratio of 0.60 (0.42 to 0.86), 0.54 (0.37 to 0.79) and 0.15 (0.06 to 0.45) for zero, one to three, four to seven, and eight or more years of schooling, respectively
  • Prevalence of obesity was 12.8% and was positively associated with female gender, family income, hypertension and diabetes and was inversely related to physical activity
  • Underweight affected 14.4% of participants, increased with age and was higher among men and low-income families
  • It was negatively associated with hypertension and diabetes and directly associated with Trypanosoma cruzi infection and more than two hospitalizations in the previous 12 months 
  • Both obesity and underweight were associated with increased morbidity.
Author Conclusion:

The association of underweight with Trypanosoma cruzi infection, increased hospitalization and low family income may reflect illness-related weight loss and social deprivation of elderly in this community. Aging in poverty may lead to an increase in nutritional deficiencies and health-related problems among the elderly.

Funding Source:
Other: FINEP
Reviewer Comments:

Different numbers of subjects were reported in the abstract vs. the full article.

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? ???
  4.1. Were follow-up methods described and the same for all groups? No
  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? 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? N/A
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? No
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