DM: Physical Activity (2007)
- diagnosis of type 2 diabetes for at least 2 years
- age > 40
- illnesses that could seriously reduce life expectancy or cause cardiac, liver, or renal failure
Recruitment : all patients attending the authors' diabetes clinic between October 1999 and January 2000 were recruited.
Design
- subjects were instructed to exercise at moderate intensity (40-60% of heart rate reserve) between 3 and 6 METS
- patients kept daily records of type, intensity, and duration of physical activity
- if subjects varied their weekly amounts of energy expenditure > 10 METS*h-1*week-1 they were transferred into a group with higher energy expenditure
- at end of study subjects were divided into groups according to average weekly increases in METs
Blinding used (if applicable) none
Intervention (if applicable)
- 30 minute counseling session with physician to advise physical activity
- phone call from same physician 1 month later
- 15 minute counseling sessions every 3 months for a total of 7 sessions
- patients were treated for diabetes according to international guidelines
- overweight and obese patients were advised to follow a diet with a 300-kcal deficit including in the calculation the energy expenditure due to voluntary physical activity
Statistical Analysis
- change from baseline for continuous variables analyzed using paired samples t tests
- average rate of change for each variable calculated using linear regressions according to the least squares method
- a post hoc analysis divided the subjects into 6 groups according to METs*hour-1*week-1, with 10-MET increments
- this analysis was conducted using ANOVA with post hoc analysis (Tukey's test), and proportions were analyzed using the McNemar test.
- P values were corrected according to the modified Bonferroni procedure proposed by Finner
Timing of Measurements: taken every 3 months at outpatient follow-up visits
Dependent Variables
Primary endpoint: CHD risk according to Framingham tables
Secondary endpoints:
- body weight
- waist circumference
- BMI
- resting heart rate
- blood pressure
- HbA1C
- fasting plasma glucose
- serum total cholesterol, triglycerides, HDL, LDL
- cost analysis
- direct medical costs, averaged on the year 2000 costs of resources in Italy
- counseling intervention at a rate of $49 per hour
- social costs, including
- value of time spent in physical activity
- cost of shoes and fitness equipment
- transportation to exercise place
- cost of memberships to fitness clubs
- cost of time lost to work or usual activities due to counseling sessions, illness, or injury
Independent Variables
- exercise counseling intervention
Control Variables
Initial N:182; 88 men
Attrition (final N): 179
Age: 62±0.7 years
Ethnicity: not specified
Other relevant demographics:
Anthropometrics: age, duration of diabetes, male-to-female ratio, and baseline levels of voluntary physical activity did not differ between groups
Location: Italy
69% of the subjects met the study goal of changing their energy expenditure by 10 METS per hour per week.
The intervention increased energy expenditure through voluntary activity by 26±2 METS per hour per week (P<0.0001) in the whole group.
Changes in outcomes of type 2 diabetic subjects divided into six groups on the basis of different amounts of energy expenditure.
Variables |
Group 0 (no increase in METs) n=28
A |
Group 1-10 (weekly increase of 1-10 METS) n=27 B |
Group 11-20 n=31
C |
Group 21-30 n=27
D |
Group 31-40 n=32
E |
Group >40 n=34
F |
Between Group Comp arisons | |
P | Post hoc analysis | |||||||
Energy Expenditure , METS*hr-1*week-1 |
0.6±0.3 |
6.3±0.4 | 17.0±0.4 | 27.0±0.5 | 37.5±0.5 | 58.3±1.8 | 0.000 | all groups differ |
Weight, kg |
0.8±0.5 |
0.6±0.7 | 0.1±0.3 | -2.2±0.2** |
-3.0±0.3** |
-3.2±0.3** |
0.268 | |
BMI | 0.3±0.2 | 0.3±0.3 | 0.03±0.1 | -0.8±0.1** | -1.0±0.1** | -1.2±0.1 ** | 0.256 | |
Waist circumference, cm |
1.0±0.7 |
1.0±0.9 | -0.9±0.4 | -3.8±0.3** |
-5.5±0.4 ** |
-7.1±0.5** |
0.000 | ABC vs. F |
FPG, mmol/l | 1.6±2.9 | -0.02±0.3 | -0.39±0.2 | -1.2±0.2** | -1.6±0.3** | -1.5±0.1 ** | 0.000 | A vs. F, B vs. DEF, C vs EF |
HbA1c, % | 0.03±0.01 | -0.06±0.09 | -0.4±0.1** | -0.9±0.07** | -1.1±0.1** | -1.0±0.1 ** | 0.001 | B vs. EF |
Maximum blood pressure, mmHG | -1.8±0.9 | -1.5±0.9 | -6.4±2.4 * | -5.6±2.7* | -6.6±1.0** |
-9.1±0.6 ** |
0.061 |
|
Minimum blood pressure, mmHg | -4.6±2.5 | -2.4±0.9 | -2.9±1.6 * | -4.8±1.8* | -5.3±0.7** | -7.1±1.0 ** | 0.000 | A vs EF, B vs. EF |
Heart rate bpm | 1.1±0.7 | 0.5±0.9 | -0.9±0.4 | -3.8±0.3** | -5.6±0.4** | -7.0±0.5** | 0.000 | A vs. EF, B vs. F, C vs. F |
Total Cholesterol, mmol/l | -0.1±0.05 | -0.1±0.1 | -0.3±0.1 * | -0.3±0.1** | -0.2±0.1** | -0.3±0.1 ** | 0.314 | |
LDL, mmol/l | -0.1±0.1 | -0.2±0.1 | -0.1±0.1 | -0.1±0.1* | 0.2±0.1* | -0.2±0.1* | 0.376 | |
HDL, mmol/l | 0.1±0.1 | 1.0±0.1 | 0.1±0.1 | 0.1±0.1** | 0.3±0.1** | 0.2±0.1** | 0.000 | ABC vs. EF |
Triglycerides, mmol/l | 0.1±0.1 | 0.1±0.1 | -0.5±0.1 ** | -0.6±0.1** | -0.6±0.1** | -0.8±0.1 ** | 0.000 | AB vs. CDEF |
10_year CHD risk, % | 0.1±0.3 | -0.3±0.5 | -2.6±0.6 ** | -3.7±0.7 | -4.8±1.0 | -4.3±1.0 | 0.000 | A vs. CDEF |
*statistically significant from baseline at P between 0.04 and 0.0003
**statistically significant from baseline at P <0.0001
Changes in outcomes of all subjects
Outcome | Change | P value |
Energy expenditure, METs*h-1*wk-1 | 26.0±1.7 | <0.01 |
Weight, kg | -1.3±0.2 | <0.01 |
BMI | -0.4 | <0.01 |
Waist, cm | -2.7 | <0.01 |
FPG, mmol/l | -0.8 | <0.01 |
HbA1c, mmol/l | -0.6±0.1 | <0.01 |
Systolic blood pressure, mmHg | -5.4±0.6 | <0.01 |
Diastolic blood pressure, mmHg | -4.6±1.0 | <0.01 |
Heart rate, bpm | -2.80.5 | <0.01 |
Total cholesterol, mmol/l | -0.2±0.1 | <0.01 |
LDL, mmol/l | -0.2±0.1 | <0.01 |
HDL, mmol/l | 0.1±0.1 | <0.01 |
triglycerides, mmol/l | -0.4±0.1 | <0.01 |
10-year CHD risk | -2.7±1.0 | <0.05 |
Other Findings
Effect of changes in energy expenditure on medical and social costs over two years
Energy Expenditure Group | Change in medical and social costs per person | P value |
Group 0 (no change in energy expenditure) | Increase of $828 | <0.01 |
Group 1-10 | no change | |
Group 11-20 | decrease of $386 | <0.0001 |
Group 21-30 | decrease of $1452 | <0.0001 |
Group 31-40 | decrease of $2000 | <0.0001 |
Group >40 | decrease of $2000 | <0.0001 |
Entire Group | decrease of $855 | <0.0001 |
In 2 years, a daily 3-mile walk is estimated to reduce drug costs by $550, other medical costs by $700, indirect social costs by $1100, total costs by $2000, and to increase direct social costs by $400.
This study demonstrates that physical activity is an effective cost-saving tool in the care of type 2 diabetes.
These results confirm the advice of several scientific societies recommending 30 minutes or more of moderate-intensity physcial activity (>10 METs*h-1*week-1) on most days is valid for type 2 subjects and demonstrates a significant dose-response relationship.
Energy expenditure must be >10 METs*hr-1*week-1 for significant beneficial effects.
Energy expenditure ranging between 11 and 20 METs*hr-1*week-1 significantly reduced HbA1c, total cholesterol, triglycerides, and blood pressure and reduced 10-year CHD risk by 2.6%.
Energy expenditure >20 METs*hr-1*week-1 is needed to decrease body weight, BMI, Waist circumference, heart rate, and LDL cholesterol and to augment HDL. This amount will reduce 10-year CHD risk by 4-5%.
Quality Criteria Checklist: Primary Research
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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? | 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.) | 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? | 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? | No | |
6.1. | In RCT or other intervention trial, were protocols described for all regimens studied? | No | |
6.2. | In observational study, were interventions, study settings, and clinicians/provider described? | N/A | |
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? | ??? | |
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? | 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? | ??? | |
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)? | No | |
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? | No | |
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 | |