EAL

DLM: BMI (2001)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To examine the relation of both waist to hip ratio (WHR) and body mass index (BMI) with 5-year mortality in a cohort of older women.

Inclusion Criteria:

Women between 55 to 69 years of age who had a valid driver's license in 1985.

Exclusion Criteria:

Missing data

Description of Study Protocol:

January 1986, a mailed questionnaire was completed by 41,837 (43% response rate) of randomly selected women 55 to 69 years of age who had a valid Iowa driver’s license in 1985. Follow-up for 5 years to identify those who died and the cause of death. Baseline questionnaire: Educational level, marital status, smoking history, alcohol intake HRT, reproductive history, prevalent diseases (cancer, MI, anti, or other heart disease, diabetes,) leisure physical activity, and FFQ to assess total fat, animal fat, and vegetable fat as percentages of caloric intake only. Reported height, current weight and weight 1-year prior and at ages 18, 30, 40, 50 years. A tape measure and written instructions given for friend to measure waist and hips.

Data Collection Summary:

Outcome measures: Total mortality

Description of Actual Data Sample:

41,177 had complete information for analysis. 1535 deaths (1504 available for analysis) 234 CVD deaths (32% of deaths )

Summary of Results:

98% white, 81% had > high school diploma, 76% married, 43% drank alcohol, 15% smoked, 98% menopausal, 11% used ERT mean BMI = 27+5 mean WHR = 0.84+0.09 Multivariate RR for death from CVD (adjusted for age, educational level, alcohol use, estrogen use, smoking status, cigarettes/day) were as follows? Death from CVD: 1) RR for quintiles of BMI were 1.0, 0.76, 0.65, 0.76 and 1.03 (P=0.94) 2) RR for quintiles of WHR Were 1.0 1.67, 1.86, 2.77, 3.39 (P for trend <0.001) Adjusted for age, BMI, smoking education level, marital status, estrogen use and alcohol use, a 0.15 unit ú in waist/hip circumference ratio was associated with a 60% greater RR of death. BMI was associated with mortality in a J-shaped fashion: rates were elevated in the leanest and the most obese women. In contrast, WHR was strongly and positively associated with mortality in a dose-response manner.

Author Conclusion:

Waist/hip circumference ratio is a better marker than BMI for risk of death in older women. Waist/hip circumference ratio should be measured as part of routine surveillance and risk monitoring in medical practice.

Funding Source:

Government:	National Cancer Institute, Cenets for Disease Control, National Institutes of Health
University/Hospital:	University of Minnesota, University of Miami

Reviewer Comments:

One of the limitations of this study was self-report of height and weight including self (or friend) measurements of waist and hips, however the authors documented the reliability and accuracy of height , weight, and waist and hip circumferences in the study cohort.
Respnse rate was only 43%.
Although respondants seemed similar to nonrespondants for several characteristics, the association of body size and shape with mortality may have been distorted in responders compared to the reference population.
Follow-up only lasted five hears - which may indicate that some women with high WHR may have had subclinical disease.
No physiological data were collected to ascertain the possible mechanisms by which WHR confers mortality risk.
Self-report of disease and physical activity may have contributed to a low estimate of their associatoiin with mortality.
The findings may not be generalizable to other race, age, and sex groups.

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)	N/A
	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.)	No
	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?		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?	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?	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