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NC: Diabetes Management (2007)

Citation:

Argus-Collins TD, Kumanyika SK, Ten Have TR, Adams-Campbell L; A Randomized controlled trial of weight reduction and exercise for diabetes management in older African-American subjects. Diabetes Care, October 1, 1997; Vol 20, No. 10 pp. 1,503-1,511.

 
Study Design:
Randomized Controlled Trial
Class:
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To assess the benefits of a weight loss and exercise program vs. a minimal intervention approximating "usual care" on diabetes management in elderly African Americans with NIDDM.

Inclusion Criteria:
  • African-American
  • At least 55 years of age
  • Diagnosis of NIDDM by medical history
  • At least 120% of Metropolitan weight standards
  • HbA1c levels over 8%.
Exclusion Criteria:
  • Does not meet above criteria
  • Unable to participate in exercise component of intervention.
Description of Study Protocol:

Recruitment

Participants recruited from general medicine clinics, diabetes clinics, public health department geriatric clinic, private practices of African-American physicians, through community outreach (announcements in newsletters and church bulletins, fliers distributed in clinics and at churches and presentations at community gatherings).

Design

Subjects were classified by type of medication prescribed (insulin or oral agents and dietary therapy) and were then assigned randomly (1:1 ratio within the medication strata) to either intervention or usual care.

Intervention

The intervention consisted of a weight loss and exercise program, which included an individualized weight reduction diet using the Diabetic Exchange Lists for meal planning, 12 weekly classes including one hour of nutrition education followed by 30 minutes of exercise for the first three months, and then bi-weekly classes for the next three months. The intervention objectives were to promote adherence to a diet with 55-60% kcal from carbohydrate, 12 to 20% from protein and more than 30% from fat, a weight loss of at least 10 pounds at the rate of  two pounds per week and moderate physical activity at least three days per week. The intervention was culturally geared to elderly African-American persons. The behavioral component of the nutrition education was based on Social Action Theory. This included topics such as relapse prevention and weight maintenance and strategies such as goal-setting, controlling or avoiding triggers to eat, and portion control.

The "usual care" component included one group class, held within three weeks of enrollment, and they received two mailings of nutrition information at approximately three and six months. They received baseline, mid- and post-treatment measurements on the same schedule and under the same conditions as those in the intervention arm of the study

Statistical Analysis

Statistical analysis were performed using SAS. Net differences in weight, activity and knowledge scores and dietary and clinical variables were calculated by subtracting the within-group change from the usual care group from the within-group change for the intervention group, separately for three or six months post-randomization. Unpaired Student's T-test was used to evaluated statistical significance of the within-group changes. Assessment of intervention-minus-control differences in each of the change variables was then carried out adjusting for different combinations of covariates using linear or logistic regression. All P-values and CI's presented are two-tailed. Variables with non-normal distributions at baseline (HbA1c, cholesterol, HDL cholesterol and weight) were log-transformed before analysis; however change distributions at three and six months were symmetrical.

Data Collection Summary:

Timing of Measurements

Baseline, three and six months.

Dependent Variables

  • Variable One: Weight; anthropometric assessments obtained by trained and certified staff member, using standardized protocol
  • Variable Two: BMI; see above; weight in kg/ht2; (height for calculation of BMI was obtained at baseline only).
  • Variable Three: Waist-to-hip ratio
  • Variable Four: HbA1c; fasting blood test; level determined by BioRad Diamat System, a system based on the principles of ion-exchange high-performance liquid chromatography (normal under 6%)
  • Variable Five: Systolic blood pressure (mmHg); sitting, measured twice, 30 seconds apart; using conventional Baum mercury sphygmamanometer
  • Variable Six: Diastolic blood pressure (mmHg) (see above)
  • Variable Seven: Serum cholesterol; blood drawn in fasting state. Total serum cholesterol, HDL-cholesterol and TG, determined from serum using enzymatic methods with an Olympus AU 5000 analyzer
  • Variable Eight: Cholesterol-to-HDL ratio (mg/dL; see above)
  • Variable Nine: HDL-cholesterol (mg/dL) (see above)
  • Variable 10: LDL-cholesterol (mg/dL) (see above); LDL cholesterol calculated using the Friedewald  equation.
  • Variable 11: Triglycerides (see above)
  • Variable 12: VLDL Cholesterol (mg/dL) (see above)
  • Variable 13: Physical activity
  • Variable 14: Nutrition knowledge
  • Variable 15: Kilocalories; one week food frequency questionnaire adapted by Eck et al, from Willett's one-year semi-quantitative food frequency questionnaire; responses on the food frequency questionnaire were converted to nutrient values using a databased developed by the Center for Biostatistics and epidemiology at Pennsylvania State University College of Medicine. Nutrient values from the National Cancer Institute food frequency questionnaire foods database were used for foods that could be matched. Values for other foods were taken from other published or computerized databases. 
  • Variable 16: Percentage of kcal, fat (see above)
  • Variable 17: Percentage of kcal, saturated fat (see above)
  • Variable 18: Percentage kcal, carbohydrate (see above)
  • Variable 19: Dietary cholesterol (milligrams per day; see above)
  • Variable 20: Fiber (grams per day; see above)
  • Variable 21: Sodium (milligrams per day; see above)
  • Variable 22: Potassium (milligrams per day; see above).

Independent Variables

  • Attendance at classes
  • Medication: Insulin, oral, diet alone.

Control Variables

  • Age
  • Gender
  • Employed or not employed
  • Smoker or non-smoker
  • Married or not-married
  • High school education.
Description of Actual Data Sample:
  • Initial N: 64; 32 in each group; 49 female (21 female in intervention group and 28 female in usual care group)
  • Attrition (final N): 58 (91%) at three months and 55 (85%) at six months
  • Age: 55 to 79 years
  • Ethnicity: African-American
  • Anthropometrics and other variables: Groups were similar at baseline on all measures 
  • Location: Urban hospital in the African-American Community in Washington, DC.
Summary of Results:

Variables

Three-Month Net Difference Between Intervention and Control Group Six-Month Net Difference Between Intervention and Control Group
Measures

95% confidence intervals

Statistical significance of group difference at three months Measures

95% confidence intervals

Statistical significance of group difference at three months

Variable 1: Weight

-2.0

(-3.4,-0.5) 

P<0.01 -2.4

(-4.3, -0.5)

P<0.01

Variable 2: BMI

-0.8

(-1.3, -0.2)

P<0.01 -0.9

(-1.6, -0.2)

P<0.01

Variable 3: Waist/Hip ratio

-0.0004

-0.02, -.02

NS 0.004

(-0.01, 0.002)

NS

Variable 4: HbA1c -1.6

(-2.4, -0.7)

P<0.01

 

-2.4

(-4.2, -0.6)

P<0.01
Variable 5: Systolic Blood Pressure (mmHg) -8.4

(-17.2, 0.4)

NS -5.9

(-14.3, 2.4)

NS
Variable 6: Diastolic Blood Pressure (mmHg) -3.3

(-7.1, 0.5)

NS -4.0

(-7.9, -0.02)

P<0.05
Variable 7: Serum Cholesterol -9.1

(-33.0, 14.8)

NS -3.7

(-25.7, 18.3)

NS
Variable 8: Cholesterol-to-HDL Ratio (mg/dL) -0.3

(-1.1, 0.5)

NS -0.07

(-0.7, 0.6)

NS
Variable 9: HDL Cholesterol (mg/dL) -0.02

(-3.7, 3.7)

NS 0.2

(-3.3, 3.8)

NS
Variable 10: LDL Cholesterol (mg/dL) 2.3

(-12.0, 16.7)

NS -2.7

(-23.7, 18.3)

NS
Variable 11: Triglycerides -12.8

(-63.7, 38.1)

NS 14

(-25.8, 53.8)

NS
Variable 12: VLDL Cholesterol (mg/dL) -2.4

(-12.5, 7.8)

NS 3.0

(-4.9, 11.0)

NS

Variable 13: Physical Activity
(high=>400, low=0)

49.4

(19.3, 79.5)

P<0.01 8.6

(-30.4, 47.6)

NS

Variable 14: Nutrition Knowledge
(high=20, low=0)

1.4

(0.06, 2.66)

P<0.05 0.7

(-0.63, 1.99)  

NS
Variable 15: Kilocalories -411.3

-821.4, -1.2)

P<0.05 -251.5

(-719.5, 216.2)

NS

Variable 16: Percentage of Kcal, Fat
(Percentage changes reported as decimals rather than percentages)

-0.06

(-0.1, -0.02)

P<0.01 -0.03

(-0.7, 0.01)

NS
Variable 17: Percentage of Kcal, Saturated Fat -0.02

(-0.03, -0.002)

P<0.05 -0.008

(-0.02, 0.008)

NS

Variable 18: Percentage of Kcal, Carbohydrate

0.05

(0.002, 0.1)

P<0.05 0.04

(-0.02, 0.1)

NS
Variable 19: Dietary Cholesterol (milligrams per day) -85.4

(-178.7, 8.0)

NS -92

(-197.5, 13.6)

NS
Variable 20: Fiber (grams per day) -1.2

(-6.8, 4.3)

NS -1.1

(-6.8, 4.5)

NS
Variable 21: Sodium (milligrams per day) -284.0

(-740.8, 172.7)

NS -46.5

(-601.1, 508.1)

NS
Variable 22: Potassium (milligrams per day) -379.4

(-1,267.5, 508.7)

NS -277.4

(-1,191.4, 636.5)

NS

Other Findings

  • Neither physical activity, weight change, dietary variables, nor demographic, knowledge, attitude or practice variables were predictive of change in HbA1c at three or six months
  • Baseline HbA1c values were predictive of HbA1c values at three months (P-0.002) and at six months (P=0.02)
  • The only intervention factor associated with glycemic control was increase in CHO intake at three months (P=0.003)
Author Conclusion:

This study demonstrated that an appropriately designed program can yield improvements in NIDDM management among older African-Americans. Since an inclusion criteria included being able to do the physical activity component, and most of the participants came from private physicians' offices, the study group may have represented a healthier population than the general population of elderly African-Americans with NIDDM (2/3 of those ultimately eligible and randomized were referred through private physicians; clinics were less fruitful referral sources for this study).

The lack of significant effect of the program in improving lipid profiles may indicate the need to incorporate a stronger or more structured focus on the cholesterol-lowering aspects of the recommended eating pattern.

The principal limitation of this study is that six months is an insufficients duration to indicate whether any of the observed improvements can be sustained over a longer period, and if so, what level and type of contact would be needed to achieve this.  These short term results are encouraging about the possible applicability of this type of approach to older African-American adults.

Funding Source:
University/Hospital: Universidad de Oviedo (Spain)
Reviewer Comments:

This was a well-controlled study which evaluated the effects of a behavior therapy program vs. usual care on both lifestyle and clinical indicators for improved health for elderly African-American adults with NIDDM. Although changes observed were not large, there were significant differences between the intervention and usual care groups in weight, BMI and HbA1c at both three and six months. Behavioral differences, such as caloric intake, percentage of calories as fat and increase in carbohydrate intake were significant only at three months, after 12 weeks of weekly meetings, even though intervention was continued every other week for the second three months. This suggests that a much longer time of intensive intervention is necessary to make the long-term changes that are necessary for improvement in diabetes management for this population.

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? 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? 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? 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? 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? Yes
  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