EAL

DLM: Energy Balance, Obesity and Anthropometric Measurement (2005)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To compare waist circumference and waist-hip ratio (WHR) as predictors of CHD in men, and to determine whether the association is independent of BMI (i.e., obesity).

Inclusion Criteria:

Men who reported anthropometric measurements
Free from CHD, stroke, cancer or other major medical illnesses.

Exclusion Criteria:

Not specified.

Description of Study Protocol:

On the nine-year questionnaire, men participating in the Physician’s Health Study were asked to measure their waist and hip measurements. BMI was calculated as well.
A validation study in a similar population of men in the Health Professionals Follow-up Study compared the average of two technician measures to those recorded by participants in the prior year on a mailed questionnaire. The study showed a correlation of 0.97 for weight, 0.95 for waist circumference and 0.69 for WHR and 0.88 for hip circumference.

Anthropometrics

Not all covariates were obtained on every questionnaire. If the covariate was not obtained on the nine-year questionnaire, the most recently available questonnaire was used
Alcohol consumption, history of hypertension and elevated cholesterol were obtained from the seven-year questionnaire
Data on height and family history of MI were obtained on the baseline questionnaire.

Statistical Tests

Cox proportional hazards analysis was performed to adjust for age, BMI quintiles, smoking, self-selected aspirin use, parental history of MI before age 60, alcohol consumption, physical activity and multivitamin use
For each RR, the two sided P-value and 95% confidence level were calculated.

Data Collection Summary:

Cardiovascular events
Revascularization procedures
Weight
Smoking
Physical activity
History of diabetes
Aspirin and multivitamin use.

Blinding Used:

Not for BMI but for beta-carotene.

Description of Actual Data Sample:

N=16,164 men who reported anthropometric measurements in the Physicians' Health Study.

Summary of Results:

Multivariate RR for CHD and MI adjusted for age, randomized beta-carotene assignment, aspirin use, smoking, parental history of MI, physical activity, alcohol consumption and multivitamin use.

Waist to Hip Ratio

Percent (%)	Relative Risk (RR)
<0.90	1.0
0.90 to0.92	0.97
0.92 to 0.95	0.99
0.95 to 0.99	1.20
>0.99	1.23

P-value 0.05.

Waist Circumference

Centimeters (cm)	Relative Risk (RR)
<88.4	1.0
88.4 to <92.7	0.90
92.7 to <97.3	1.10
97.3 to <103.6	0.94
>103.6	1.06

P-value 0.69.

Body Mass Index (BMI)

Kg/m²	Relative Risk (RR)
<22.8	1.0
22.8 to <24.3	1.31
24.3 to <25.7	1.23
25.7 to <27.6	1.62
>27.6	1.73

P-value 0.0001.

Author Conclusion:

“There is a modest relationship between abdominal adiposity, as measured by either WHR or waist circumference and risk of CHD in both middle-aged and older men"
" Abdominal adiposity did not remain an independent predictor after adjustment for BMI.”

Funding Source:

Government:

NIH

Reviewer Comments:

Strengths:

Assumed accuracy of reporting as physicians
Validation studies confirmed the reliability of self-reported weight
There were adjustments for variables
Credible use of statistics.

Generalizability/Weaknesses:

Since WHR involves two measurements, there is greater room for error
Subjects are somewhat healthier than the general population and have lower rates of obesity
Cohort is predominately White, middle-class and older.

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)	Yes
	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)	Yes

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.)	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%.)	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?	Yes
	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?	Yes
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	N/A
	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?	Yes
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	Yes
	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?	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