EAL

DLM and Physical Activity

Citation:

Lemaitre RN, Heckbert SR, Psaty BM, Siscovick DS. Leisure-time physical activity and the risk of non-fatal myocardial infarction in postmenopausal women. Arch Intern Med. 1995;155:2302-2.

Worksheet created prior to Spring 2004 using earlier ADA research analysis template.

Study Design:

nonrandomized trial with concurrent or historical controlsCase-control

Class:

C - Click here for explanation of classification scheme.

Quality Rating:

NEGATIVE: See Quality Criteria Checklist below.

Research Purpose:

Inclusion Criteria:

Cases: postmenopausal women: MI July 1986- December 1991 Index date: hospital admission for MI Identified potential cases: 1. computerized discharge abstracts for 2 GHC hospitals 2. GHC claims databases including bills for all services provided

Exclusion Criteria:

1. Belonged to CHC < 1 yr. 2. < 4 visits before index date 3. prior MI 4. non postmenopausal

Description of Study Protocol:

Group Health Cooperative (GHC) of Puget sound, an HMO based in Seattle, WA

Data Collection Summary:

Controls: Stratified random sample of GHC enrollees who were matched to cases by age (by decade) and calendar year. Index date: computer-generated random date within same calendar year as MI of matched case Data collection: Medical record Telephone interview (physical activity) using Minnesota Leisure-Time Activity Questionnaire Outcome measure: MI

Description of Actual Data Sample:

Identified 543 eligible cases of nonfatal MI and 1644 controls during 5.5-year study period. Reviewed outpatent medical records of 507 cases and 1571 controls (denied access to medical records of 27 cases and 73 controls). 268 cases (50.2% of identified cases) and 925 controls (56.3% controls) provided complete information on leisure time physial activity.

Summary of Results:

After adjustment for potential confounding factors, the odds ratios for nonfatal MI for women in the second, third, and fourth quartile of total energy expenditure, relative to women in the first quartile, were: 0.52 (95% CI, 0.34-0.80) 0.40 (95% CI, 0.26 to 0.63) 0.40 (95% CI, 0.25 to 0.63) Controls expended significantly more energy on physical activities 1506 kcal/wk than cases: 1243 kcal/wk (P<0.05) This study suggests that the risk of MI among postmenopausal women is ¯ 50% with modest leisure-time energy expenditures, equivalent to 30-45 minutes of walking 3 times per week.

Author Conclusion:

~50% of identified cases and controls provided complete data for the study (subject or MD gave permission to read medical record; subject participated in telephone interview) Baseline differences between cases and controls ¯ the strength of this study. The differences between cases and controls that were significant (P<0.05) were: Cases Controls % Diabetes 19.8 6.9 Angina 27.6 7.6 Smoker 32.5 15.2 Systolic BP Mm Hg 142.9 138.0 T chol (mmol/L) 6.7 6.2

Funding Source:

Government:

NHLBI

Reviewer Comments:

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?	No
	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?	N/A
	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.)	Yes
	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?		No
	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%.)	No
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	???
	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?	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.)	No
	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?	Yes
	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?	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?	Yes
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	No
	6.6.	Were extra or unplanned treatments described?	No
	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?	???
	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)?	???
	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