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DLM: Physical Activity (2001)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

To investigate the independent associations of physical activity during leisure time and maximal oxygen uptake with the risk of acute myocardial infarction (MI).

Inclusion Criteria:
  • Random sample of men living in Kuopio or neighboring rural communities and balanced according to age
  • 83% of eligible men participated.
Exclusion Criteria:

History of CVD or cancer.

Description of Study Protocol:
  • The Kuopio Ischemic Heart Disease Risk Factor Study
  • 1,453 Finnish men
  • 42 to 60 years of age
  • Examined between March 1984 and December 1989
  • Followed for approximately five years.
Data Collection Summary:
  • Data collected: Medical history, family history, blood samples
  • Physical activity: 12-month history modified from the Minnesota Leisure Time Physical Activity Questionnaire which evaluated frequency, average duration and intensity
  • Cardiorespiratory fitness:
    • Exercise-tolerance test on electrically braked bicycle ergometer with EKG
    • Maximal O2 uptake
  • Outcome measures: MI.
Description of Actual Data Sample:
  • Age: Subjects ranged in age from 42 to 61.2 years
  • Mean age: 52 years
  • Fatal or nonfatal MI: 57
  • Non-CHD deaths: 38
Summary of Results:
  • Most spent more of leisure time on non-conditioning physical activity
  • After adjustment for age and the year of exam, the RR of MI in the third of subjects with the ú level of physical activity (greater than 2.2 hours per week) was 0.31 (95% CI, 0.12 to 0.85) P=0.02 compared with the third level of physical activity (P=0.04 for linear trend over all three groups)
  • The RR in the third with the ú maximal O2 uptake (greater than 2.7L per minute) was 0.26 (95% CI, 0.10 to 0.68) P=0.006 for linear trend (adjusting for age, year and season of exam)
  • After up to 17 confounding variables were controlled for, the RR for the third of subjects with the ú level of physical activity (0.34, 95% CI, 0.12 to 0.94) P=0.04; and maximal O2 uptake (0.35; 95% CI 0.13 to 0.92;) P=0.03), as compared with the values in the lowest third, were significantly less than 1.0 (P<0.05)
  • Increased levels of leisure-time physical activity and cardiorespiratory fitness had a strong, graded, inverse association with the risk of acute MI; physical activity and cardiorespiratory fitness are independent risk factors for CHD in men
  • Factors significantly associated with the risk of MI were the number of pack-years of cigarette smoking (P=0.001), family history of CHD (P=0.01), maximal O2 uptake (P=0.02) and duration of conditioning physical activity (P=0.03).
Author Conclusion:
  • Physical activity categorized according to type:
    • Conditioning: Walking, jogging, skiing, bicycling, swimming, rowing, ball games, gymnastics, dancing, weight lifting
    • Non-conditioning: Crafts, repairs, building, yard work, gardening, farming, snow shoveling, hunting, picking berries, gathering mushrooms, fishing, forest activities less intense walking and bicycling.
Funding Source:
Government: Finnish Ministry of Education, town of Kuopio
University/Hospital: University of Kuopio
Not-for-profit
0
Foundation associated with industry:
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? 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? ???
  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%.) ???
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? ???
  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? No
  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? 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? 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)? ???
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? ???
  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