EAL

DLM and Physical Activity

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To relate established disease, and CVD risk factors to all-cause mortality in normal-weight, overweight, and obese men with low cardiorespiratory fitness.

Inclusion Criteria:

Study uses data from the Aerobics Center Longitudinal Study in Dallas, TX, obtained between 1970 and 1993.

Exclusion Criteria:

History of cancer BMI <18.5 <20 years of age <1 year of follow-up

Description of Study Protocol:

Recruitment: 25,714 men who received medical exam during 1970-1993 at Cooper Clinic, Dallas, TX

Study Design: baseline measure compared to CVD and all-cause mortality during a 10-year period, with all participants being followed for at least one year

Statistical analysis:

Cox partial likelihoot method used to provide point estimates and 95% CI adjusted for Age, examination year, and parental history of CVD
crude and net survival for all weight categories
Age and examination year-adjusted CVD and all-cause mortality for the three categoreis
mult-variate-adjusted population-attributable risks calculated

Data Collection Summary:

Dependent Variables:

CVD mortality All-cause morality Above based on mortality predictors stratified by BMI (baseline CVD, Type 2 diabetes mellitus, increased t chol, hypertension, smoking, decreased cardiorespiratory fitness)

Independent variables:

Medical history at baseline: 1. CVD 2. type 2 diabetes mellitus 3. t chol 4. hypertension 5. cigarette smoking 6. cardiorespiratory fitness 7. body weight 8. cardiorespiratory fitness (maximal exercise test on treadmill)

Description of Actual Data Sample:

Sample Size: 25,714 men

Age: Mean age: 43.8+10.1 years

Demographic Data: subjects were 90% white; 80% had college educations; most were executives and professionals

Anthropometric Data

Normal-weight (41% of total): Mean BMI 23.2±1.3
Overweight 46% of total): Mean BMI 27.0±1.4
Obese (13% of total): Mean BMI 33.2±3.7

Location: United States

Summary of Results:

During the 10-year follow-up period there were 1025 deaths, 439 due to CVD

Mortality Predictor	Normal weight RR (95% CI)	Overweight RR (95% CI)	Obese RR (95% CI)
CVD No	1.0 (referent)	2.0 ( 1.5-2.8)	2.6 (1.6-4.0)
CVD Yes	6.9 (4.8-8.9)	8.1 (6.4-12.3)	14.0 (9.4-20.8)
Type 2 Diabetes Yes	1.0 (referent)	1.7 (1.4-2.2)	2.5 (1.8-3.4)
No	2.2 (1.4-3.6)	3.9 (2.8-5.6)	4.9 (3.2-7.7)
Cholesterol Levels <6.2 mmol (< 240 mg'dL	1.0 (referent)	1.6 (1.2-2.1)	2.1 (1.4-3.1)
>6.2 mmol (>240 mg/dl	1.4 (0.9-2.0)	2.8 (2.1-3.7)	4.7 (3.2-6.8)
Hypertension No	1.0 (referent)	2.1 (1.6-2.9)	3.4 (2.2-5.1)
Yes	2.6 (1.9-3.8)	3.4 (2.5-4.6)	4.5 (3.0-6.6)
Current smoker No	1.0 (referent)	1.8 (1.4-2.4)	2.9 (2.0-4.0)
Yes	2.1 (1.4-3.1)	3.3 (2.4-4.5)	4.4 (2.7-7.1)
Low fitness No	1.0 (referent)	1.5 (1.1-2.0)	1.6 (1.0-2.8)
Yes	3.1 (2.2-4.5)	4.5 (3.2-6.0)	5.0 ( 3.8-7.0)

Decreased cardiorespiratory fitness was a strong and independent predictor of CVD and all-cause mortality, comparable to that of diabetes mellitus and other CVD risk factors.

Author Conclusion:

"low cardiorespiratory fitness is as important as type 2 DM ad other CVD risk factors as a predictor of CVD mortality and all-cause mortality in overweight or obese men."

Funding Source:

Government:

NIA

Reviewer Comments:

Study limitations: study included only men primarily from middle and upper-socioeconomic backgrounds.

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?	No
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?		N/A
	4.1.	Were follow-up methods described and the same for all groups?	N/A
	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?	N/A
	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?	No
	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?	N/A
	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?		N/A
	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?		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?	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