FNOA: Assessment of Overweight/Obesity (2012)
To investigate the association between BMI and long-term mortality (9 years) in disabled and non-disabled older individuals (> 65 years old) using disability-focused data from the 1994 National Long-Term Care Survey.
Individuals who participated in the 1994 National Long-Term Care Survey.
Data from individuals who did not report height and weight in the 1994 NLTCS were excluded.
Recruitment
Data from the 1994 National Long-Term Care Survey (NLTCS).
Design: Cohort study
The authors used data from the 1994 NLTCS; Medicare vital statistics files linked to the NLTCS during the 9 years of follow-up were analyzed to look at the ability of change in BMI to predict death.
Blinding used (if applicable): not applicable
Intervention (if applicable): not applicable
Statistical Analysis
Cox proportional hazard regression models; BMI 22.0 - 24.9 was used as the reference category. The robustness of the estimates was tested by adjusting for age and sex and confounders; excluding smokers and proxy reports of weight; and stratification according to disability as well as age-stratification for disabled and non-disabled individuals.
Timing of Measurements
9 years of follow-up measurements, linked to Medicare vital statistics files.
Dependent Variables
- Mortality
Independent Variables
- Body Mass Index (BMI) based om height and weight which were based on self- and proxy report
- Disability
Control Variables
- Alcohol consumption
- Smoking status
- Health conditions (cancer, heart attack, stroke, other heart problems)
- Activities of Daily Living (ADL)
- Instrumental Activities of Daily Living (IADL)
- Race (Black, white, other)
- Baseline information for mediators of obesity on mortality (such as hypertension, diabetes)
Initial N: The 1994 NLTCS represented 5,088 individuals.
Attrition (final N): 297 individuals were excluded due to missing height and weight information; 2,956 individuals died during the 9 years of follow-up. Data for 4,791 individuals were analyzed.
Age: > 65 years
Ethnicity: The sample was primarily white.
Other relevant demographics: The sample included more men than women. 1,762 individuals of the sample (noninstitutionalized, unimpaired) were designated to be included as a "healthy supplement" and better represent nondisabled individuals.
Anthropometrics
Location: The sample was nationally representative of the United States
Key Findings
- Overweight and Grade 1 Obesity (BMI 25.0 - 34.9) appear not to be a risk factor for 9-year mortality in individuals age 65 and older.
- Older individuals can be more tolerant of being overweight than younger individuals.
- Nondisabled older individuals have a narrower range of tolerable deviations from optimal weight than disabled older individuals.
- The health and well-being of older individuals should be considered when recommending optimal body weight.
Relative Risk of Death According to Selected BMI Categories (95% Confidence Interval) | |||||
Age (years) |
BMI <18.5 |
BMI 18.5 - 21.9 |
BMI 25.0 - 29.9 | BMI 30.0 - 34.9 | BMI > 35.0 |
Nondisabled 65 - 74 y |
1.61 (P>0.05) (0.36- 7.12) |
1.23 (P>0.05) (0.60- 2.53) |
0.90 (P>0.05) (0.53- 1.55) | 1.09 (P>0.05) (0.56 - 2.13) | 1.23 (P>0.05) (0.53 - 2.83) |
Nondisabled 75 - 84 y |
1.16 (P>0.05) (0.63 - 2.14) |
1.14 (P>0.05) (0.80 - 1.62) |
0.62 (0.46-0.85) |
0.58 (0.36 - 0.94) | 1.20 (P>0.05) (0.60-2.43) |
Nondisabled >85 y |
1.30 (P>0.05) (0.53- 3.16) |
1.02 (P>0.05) (0.55-1.90) |
0.80 (P>0.05) (0.36-1.77) |
--- | --- |
Disabled 65 - 74 y |
1.89 (0.94-3.80) | 1.12 (P>0.05) (0.65-1.92) | 0.52 (0.33-0.82) | 0.63 (P>0.05) (0.38-1.07) | 0.92 (P>0.05) (0.56-1.52) |
Disabled 75 - 84 y |
2.09 (1.44-3.03) | 1.84 (1.43-2.37) | 0.95 (P>0.05) (0.76-1.18) | 0.87 (P>0.05) (0.65-1.16) | 0.84 (P>0.05) (0.59-1.20) |
Disabled >85 y |
1.42 (P>0.05) (0.96-2.10) | 1.26 (P>0.05) (0.92-1.71) | 1.07 (P>0.05) (0.78-1.45) | 1.07 (P>0.05) (0.67-1.72) | 3.04 (1.27-7.27) |
Other Findings
BMI patterns are age-sensitive; disability affects this sensitivity.
Overweight and grade 1 obesity (BMI 25.0 - 34.9) appear not to be a risk factor for 9-year mortality in individuals age 65 and older who participated in the 1994 National Long-Term Care Survey. BMI patterns relative to risk of death are age-sensitive and disability affects this sensitivity; health and well-being of older adults should be considered when recommending an optimal body weight.
Government: | National Institute on Aging |
Large, nationally representative sample. Height and weight based on self- and proxy reports.
Quality Criteria Checklist: Primary Research
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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? | N/A | |
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.) | 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? | No | |
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.) | No | |
5.3. | In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? | No | |
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? | No | |
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? | No | |
7.5. | Was the measurement of effect at an appropriate level of precision? | ??? | |
7.6. | Were other factors accounted for (measured) that could affect outcomes? | Yes | |
7.7. | Were the measurements conducted consistently across groups? | ??? | |
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 | |