EAL

FNOA: Assessment of Overweight/Obesity (2012)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To examine the relation between other anthropometric indices of body composition (both muscle mass and body fat) and all-cause mortality in men aged 60 to 79 years.

Inclusion Criteria:

Men aged 40 to 59 years (78% response rate) drawn from one general practice in each of 24 towns representing all major British regions
Initially examined between 1978 and 1980 as part of the British Regional Heart Study
All surviving men, now aged 60 to 79 years, were invited to a 20th-year re-examination.

Exclusion Criteria:

All men with diagnosed heart failure.

Description of Study Protocol:

Recruitment

Men drawn from one general practice in each of 24 towns representing all major British regions
Initially examined between 1978 and 1980 as part of the British Regional Heart Study
All surviving men were invited to a 20th-year re-examination.

Design

Prospective cohort study
Measurements at re-examination included height, weight, waist and hip circumference, midarm muscle circumference (MAMC), fat mass and fat free mass. Cardiovascular risk factors were collected using a follow-up questionnaire, as well as measurement of lung function (FEV1), glomerular filtration rate (CRP) and estimated serum creatinine.

Blinding Used

Implied with measurements.

Statistical Analysis

Statistical analyses were performed by using SAS software
Cox's proportional hazards model was used to assess the adjusted relative risk (RR) for the adiposity variables
In the adjustment, smoking, social class, alcohol intake, physical activity, weight loss, height loss and the presence of diseases were fitted as categorical variables. Age, FEV1, albumin and CRP were fitted as continuous variables.
- Cox regression adjusted for age
- Model two was adjusted for age, social class, physical activity, alcohol intake and smoking
- Model two + MAMC was adjusted, as was model two, with the addition of midarm muscle circumference (MAMC).

Data Collection Summary:

Timing of Measurements

Initial examination: 1978 to 1980
Re-examination: 1998 to 2000.

Dependent Variables

Adjusted relative risk of mortality.

Independent Variables

Height
Weight
Waist and hip circumferences
Skinfold thickness
Midupper arm muscle circumference
Body Mass Index (BMI), calculated
Fat mass (FM) and fat-free mass (FFM) calculated using bioelectrical impedance
Height loss, calculated.

Control Variables

Age
Cardiovascular risk factors assessed with a questionnaire (smoking status, social class, blood pressure)
Alcohol intake
Physical activity
Forced expiratory volume (FEV1) measured
Glomerular filtration rate (eGFR) estimated from serum creatinine
Albumin
C-reactive protein (CRP), assayed by using ultrasensitive nephelometry.

Description of Actual Data Sample:

Initial N: 4,252 men
Attrition (final N): 4,107 men
Age: 60 to 79 years at follow-up
Ethnicity: 97.4% white
Location: Great Britain.

Summary of Results:

Key Findings

	Number of Deaths	Rate per 1,000 Person-years	Rate per 1,000 Person-years	Adjusted Relative Risk (95% CI)
High²
WC≤102cm (N=1,169)	125	17.4	1.00	1.00
WC>102cm (N=844)	143	28.4	1.52 (1.19, 1.93)	1.36 (1.07, 1.74)
Medium³
WC≤102cm (N=794)	116	24.7	1.19 (0.92, 1.53)	1.14 (0.88, 1.47)
WC>102cm (N=204)	49	42.7	2.05 (1.47, 2.86)	1.88 (1.35, 2.63)
Low⁴
WC≤102cm (N=891)	217	42.8	1.83 (1.46, 2.29)	1.67 (1.33, 2.10)
WC>102cm (N=95)	26	47.8	1.94 (1.27, 2.97)	1.55 (1.01, 2.39)

²High MAMC was defined as above the median (more than 26.43).

³Median MAMC was defined as second quartile (24.92 to 26.42).

⁴Low MAMC was defined as lowest quartile (less than 24.92cm)

Underweight men (BMI less than 18.5) had exceptionally high mortality rates
After the exclusion of underweight men, increased adiposity showed little relation with mortality after adjustment for lifestyle characteristics
Muscle mass was significantly and inversely associated with mortality
After adjustment for midarm muscle circumference, obesity markers, particularly high waist circumference (more than 102cm) and waist-to-hip ratio (top quartile) were associated with increased mortality
Men with low WC (102cm or less) and above-median muscle mass showed the lowest mortality risk
Men with WC higher than 102cm and above-median muscle mass showed significantly increased mortality (age-adjusted risk: 1.36; 95% CI: 1.07, 1.74)
Men with WC higher than 102cm and low MAMC had increased mortality (age-adjusted risk: 1.55, 95% CI: 1.01, 2.39)
Combined effect of midarm muscle circumference (MAMC) and high waist circumference (WC) on mortality in men with no diagnosed heart failure aged 60 to 79 years, with the exclusion of underweight (BMI less than 18.5) men.

Author Conclusion:

The findings suggest that the combined use of both WC and MAMC provides simple measures of body composition to assess mortality in older men.

Funding Source:

Not-for-profit

British Heart Foundation

Other non-profit:

Reviewer Comments:

Large population-based study, adjusted for several factors. Limitations noted by author:

Only men studied
Presence of doctor-diagnosed diseases based on self-report, but other variables were measured.

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.)	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?		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