EAL

FNOA: Assessment of Overweight/Obesity (2012)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To determine the effect of age on the relationship between BMI and mortality.

Inclusion Criteria:

Hospitalized patients
Admitted to one of 79 participating clinical centers
Admitted during one of five different surveys in 1988, 1991, 1993, 1995 and 1997.

Exclusion Criteria:

Explicit diagnosis of terminal illness
Presence of an obesity-related disease (hypothyroidism, Cushing syndrome and acromegaly).

Description of Study Protocol:

Recruitment

The present study uses data from the Italian Group of Pharmacoepidemiology in the Elderly study (GIFA). All patients consecutively admitted in the 79 participating clinical centers during five different surveys were considered.

Design

Cross-sectional, observational study

Blinding used

None

Intervention

Not applicable

Statistical Analysis

Differences in categorical parameters according to age and sex were tested using the Fisher exact test. Differences in continuous variables were assessed by analysis of variance for normally distributed parameters and Kruskal-Wallis test for non-normally distributed variables.
To address whether the relationship between different levels of BMI and mortality were homogeneous in the study population, a sex-adjusted Cox proportional hazards regression model stratifying the cohort according to age was used. Adjustments were made for all possible confounders.

Data Collection Summary:

Timing of Measurements

A questionnaire was completed at admission and updated daily by a study physician. Data recorded included sociodemographic information, smoking status and alcohol intake history, main and coexisting diseases, prescribed medications, physical findings, ECG results, chest radiographic findings, CBC, neuropsychological variables, physical function variables, and cognitive status. Weight and height were measured at admission and BMI was calculated. Hospital mortality was determined at time of discharge.

Dependent Variables

Relative hazard rate of death

Independent Variables

Age
Height, weight and BMI
Sex.

Confounding Variables

Comorbidity
Physical disability
Cognitive impairment
Smoking status
Alcohol abuse.

Description of Actual Data Sample:

Initial N: 18,315
- 9,170 men
- 9,145 women
Attrition (final N): All included in final analysis
Age:
- 5,566 participants were under the age of 65
- 4,550 participants were between the ages of 65-74
- 8,199 participants were 75 years of age or older
Ethnicity: Italian
Other relevant demographics: Not reported
Anthropometrics: No differences
Location: Rome, Italy.

Summary of Results:

Key Findings

Mortality was lowest among men and women with BMIs from 25.0 through 27.4kg/m²
For patient younger than age 65, the relationship between BMI and mortality was U-shaped, with increasing death rates among the leanest and heaviest persons
In middle-aged and older patients, the relationship between BMI and mortality was J-shaped, with increased death rates at the lowest BMIs and only a slight elevation of death rates in the highest level of BMI (>35.0kg/m²).

Crude and Adjusted Relative Risks of Mortality According to BMI for Men

BMI	Dead/Alive Patients	Crude Model RR (95% CI)	Adjusted Model RR (95% CI)
<18.5	39/310	...	...
18.5-21.7	73/1,296	0.44 (0.29-0.67)	0.50 (0.32-0.77)
21.8-24.9	82/3,102	0.21(0.14-0.31)	0.29 (0.19-0.44)
25.0-27.4	46/2,143	0.17 (0.10-0.26)	0.24 (0.15-0.38)
27.5-29.9	29/1,129	0.20 (0.12-0.33)	0.28 (0.16-0.48)
30.0-34.9	14/735	0.15 (0.08-0.28)	0.22 (0.11-0.42)
>35.0	5/137	0.29 (0.11-0.75)	0.45 (0.16-1.12)

Crude and Adjusted Relative Risks of Mortality According to BMI for Women

BMI	Dead/Alive Patients	Crude Model RR (95% CI)	Adjusted Model RR (95% CI)
<18.5	55/607	...	...
18.5-21.7	80/1,746	0.50 (0.35-0.75)	0.54 (0.37-0.79)
21.8-24.9	51/2,473	0.22 (0.15-0.33)	0.30 (0.20-0.45)
25.0-27.4	31/1,714	0.19 (0.12-0.31)	0.24 (0.15-0.38)
27.5-29.9	18/1,005	0.19 (0.11-0.33)	0.25 (0.14-0.44)
30.0-34.9	18/946	0.21 (0.12-0.36)	0.28 (0.16-0.49)
>35.0	7/364	0.21 (0.09-0.47)	0.30 (0.13-0.68)

Other Findings

The overall in-hospital mortality rates were 2.9% (n=260) and 3.2% (n=288) for men and women, respectively. This was not statistically significant.

Author Conclusion:

The results of this large observational study suggest that a very low BMI has an important prognostic implication for patients in an acute care setting, independent of age, sex, and other non-nutritional risk factors
Our findings suggest that obesity does not qualify as a risk factor in hospitalized older patients, assuming that an obesity-related disease has been excluded.

Funding Source:

Government:

National Reserach Council (Italy)

Industry:

Neopharmed Italia

Pharmaceutical/Dietary Supplement Company:

Reviewer Comments:

Results apply to hospitalized patients and can not be implied to be true in community-dwelling elderly individuals
In-patient mortality was the outcome of measure. It could be reasonably assumed that each patient in the study suffered from an acute problem and the nature and severity of the in-patient diagnosis was not reported.
As noted in many of the studies looking at BMI and mortality risk in the elderly population, direct measures of adiposity were not taken and it is unknown whether patients had recently gained or lost weight
There was a higher prevalence of comorbidity and a higher range of functional impairment relative to those in the younger groups, which could be reasonably expected when investigating hospitalized individuals. These factors were adjusted for as potential confounders.

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?	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?		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?	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?	N/A
	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?	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