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NC: Social Learning Theory (2008)

Citation:

Glasgow RE, Toobert DJ, Mitchell DL, Donnelly JE, Calder D, Nutrition Education and Social Learning Interventions for Type II Diabetes. Diabetes Care. 1989; 12 (2): 150-152.

PubMed ID: 2702897
 
Study Design:
Randomized controlled trial
Class:
A - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

The purposes of this comparative study were to determine

  1. Whether a time-limited nutrition education program would improve dietary behaviors (not necessarily weight loss) more than a control condition
  2. Whether adding the social learning components of problem solving and self-efficacy would enhance the outcomes of the basic program.
Inclusion Criteria:

Type 2 diabetic patients with less than average glycemic control (i.e., glycosylated hemoglobin (GHb) over 9% or physician's judgment of poor control if GHb not available) who met the clinical criteria recommended by Welborn et al, 1983, for type 2 diabetes.

Exclusion Criteria:
  • Not having type 2 diabetes.
  • Type 2 diabetes with good control (i.e., GHb over nine).
Description of Study Protocol:

Recruitment

Article does not include information regarding how subjects were recruited.

Design

  • Subjects were type II diabetics; they were stratified by sex, mode of therapy (insulin or not) and randomly assigned to three different groups
  • Nutrition Education (NE), Nutrition Education and social learning (NE+SL) or wait-list control
  • The two study groups met weekly for five weeks in small group meetings lasting 1.5 to two hours
  • Each group was given Nutrition Education, which focused on reducing caloric intake by 500kcal to 800kcal per day, reducing fat intake to 30% of calories and increasing fiber intake by 10g to 20g per day
  • Caloric intake, fat intake and fiber intake were measured at baseline, at the end of the five-week intervention phase and at a two-month follow-up. 


Intervention

  • Five weeks of one-week meetings where subjects were given nutrition education focusing on calorie intake reduction, fat intake reduction and fiber intake increase
  • The NE+SL group also received information on goal-setting based on individual barriers to adherence  and modeling of strategies used successfully by other individuals with type 2 diabetes
  • The NE+SL group was also taught a problem-solving method called STOP (Specify the problem; Think of options; Opt for the best solution; Put the solution into practice).

Statistical Analysis

Analysis of covariance (co-varying pre-test scores).

Data Collection Summary:

Timing of Measurements

Baseline; after five-week intervention; two-months after end of program.

Dependent Variables

  • Variable One: Caloric intake; subjects used a food record to record intake for three consecutive days (two weekdays and one weekend day), method for evaluating food records not reported
  • Variable Two: Mean percentage of calories from fat intake (from food records above)
  • Variable Three: Mean grams of fiber intake.

Independent Variables

  • Variable One: NE, NE+SL or wait-list control group
  • Variable Two: Initial dietary intake of calories and grams fiber
  • Variable Three: Initial percentage of fat intake
  • Variable Four: Initial fiber intake.

Control Variables

  • Variable One: Mode of therapy (insulin or not)
  • Variable Two: Sex
  • Variable Three: Physician.
Description of Actual Data Sample:

Initial N

78 outpatients; 73% women

Attrition (final N)

  • 74 (95%) subjects completed the five-week program and post-test; the four drop-outs were from the control group
  • 59 subjects, 20 from NE group; 23 from NE+SL group and 16 from control group, (76% of initial N; 80% of post-test group) participated in the two-month follow-up.

Age

42 to 75 years.

Ethnicity

Not reported.

Other Relevant Demographics

Baseline fasting blood glucose levels averaged 175mg/dL; initial GHb averaged 9.7%; 42% were prescribed oral diabetes medication and 39% took insulin (presumably the remaining 19% were managed by diet).

Anthropometrics

Average percentage of desireable weight was 153%.

Location

Outpatient setting; specific type of facility not reported.

Summary of Results:

 

Variables

 

NE Treatment Group

Measures and Confidence Intervals

NE+SL Treatment Group

Control Group

Measures and Confidence Intervals

Statistical Significance of Group Difference

Dependent Variable One: Caloric Intake

Pre-test

1,657.9±508.8

1,874.8±582.4

1,835.2±643.2

Statistical significance within groups; pre-test to two-month follow-up

NE group P<0.05

NE+SL group P<0.01 at post-test and P<0.001 at two-month follow-up

Control group: Not significant

Between group: Combined NE and NE+SL significantly different from control P<0.05

 

Post-test 

1,657.7±458.7 1,651.2±-527.8 1,788.9±547
Two-month follow-up 1,519.8±450.9 1,554.1±504.8 1,818.1±471.5

Dependent Variable Two:  Mean Percent Calories from Fat

Pre-test 36.2±8 40.6±7 38.5±9.7

Statistical significance within groups:

NE: Not significant

NE+SL: P<0.01 at post-test and two month follow-up

Control: Not significant

Between group significance not reported

Post-test 35.6±8.2 35.7±9.5 35.3±10.4

Two-month followup

38.1±9.4

36.8±6.7

39.2±9

Dependent Variable Three: Mean Fiber Intake

Pre-test

19.8±8.5

23.3±10.8

26.2±19.4

No significant within- group changes

Between group changes: Pre-test to post-test, combined NE and NE+SL groups Significant greater increase in fiber intake, P<0.05

No significance from pre-test to two-month follow-up

Post-test 24.7±13.1 24.3±10.3 21.3±15.5
Two-month follow-up 19.0±8.6 21.9±8.0 24.2±22.8

Other Findings

  • The NE+SL group had a significant decrease in weight at the two-month follow-up (weights not taken at the post-test; P<0.05)
  • There were no significance between group differences in glycemic control or weight, but the two treatment groups had marginally greater reductions in fasting blood glucose than the control group (P<0.08)
  • There were not significant differences between the NE and NE+SL groups in either dietary or glycemic control measures.
Author Conclusion:

These brief interventions produced improvement in targeted behaviors associated with risk reduction in type 2 diabetes. This may be valuable, even if there were not significant changes in GHb or weight. Longer term follow-ups are needed to more fully evaluate the intervention effects.

Data relevant to the second question (does addition of Social Learning components of problem solving and self-efficacy enhance the outcomes of the basic program?) are less encouraging. Although within group analysis were suggestive of greater improvement in the NE+SL group, between group comparisons of NE and NE+SL did not show significant differences.

It is possible that these interventions may have worked with some types of type 2 diabetes patients and not with others.  However patient assignment strategy and preliminary analysis suggest that demographics, severity of diabetes and history of diabetes did not confound or interact with treatment outcome.

The authors believe that development and evaluation of brief interventions to assist patients in achieving specific goals are worthwhile. Such programs may reach and appeal to sizable numbers of patients but are less likely to produce improvement in other non-targeted areas such as body weight or GHb. It is possible that these brief interventions could serve as the first stage in a comprehensive stepped-care approach to diabetes education, with patients who have not reached program goals referred to more intensive and costly interventions, as has been suggested for other areas of behavior change.

Funding Source:
Government: NIH
Reviewer Comments:

This study showed that nutrition education is important in changing diabetic patients dietary behaviors. The addition of social learning concepts appeared to make a greater difference in all three areas evaluated (caloric intake, fat intake and fiber intake), but was not significant when compared to the nutrition education alone. Evaluating these study subjects further out would better show the value of a short term nutrition education intervention and whether or not the addition of social learning concepts made a significant difference. I would like to see how each of these groups were doing one year after the intervention was complete.

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? ???
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? No
  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%.) 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? ???
  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.) ???
  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? 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? 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? ???
  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? 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