HD: Effectiveness of Nutrition Intervention Methods (2010)
Citation:
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
The purpose was to test the feasibility and examine the effects of a culturally-tailored intervention for Mexican Americans with type 2 diabetes.
Research Questions
- Will Mexican American adults with type 2 diabetes agree to participate in a culturally-tailored diabetes program of three months' duration?
- Will adults who participate have significantly better behavioral and biologic outcomes than a control group?
- Behavioral outcomes: Diabetes knowledge,self-efficacy and self-management activities score
- Biologic outcomes: Blood glucose, HbA1C, weight and body mass index.
Inclusion Criteria:
- Seen in a community health clinic in Tucson, Arizona
- Self-identified Mexican-Americans
- 18-75 years of age
- Diagnosis of type 2 diabetes
- Fluent in Spanish
- Ability to walk without assistance.
Exclusion Criteria:
- Pregnant
- Medical condition in which dietary changes and exercise were contraindicated, such as heart failure
- Cognitively impaired
- Participated in a diabetes self-management program within the previous 12 months.
Description of Study Protocol:
Recruitment
- Flyers posted in high-traffic areas within the clinic
- Clinic providers and staff asked to refer prospective participants
- A bilingual promotora (lay peer educator) contacted prospective participants using the clinic's diabetes roster.
Design
Group randomized trial
Intervention Group
- Eight weekly two-hour group sessions that included
- Didactic content
- Cooking demonstrations
- Group support
- Sessions held weekdays in clinic
- Participants encouraged to bring a support person to sessions
- Modeling accomplished through the use of the promotora and the cooking demonstration.
Control Group
- Received usual care and education given by the clinic
- 15-minute encounter with a physician or nurse practitioner two to four times per year
- Pharmacological management is primary focus.
Statistical Analysis
- Groups compared using independent samples T-tests and chi-square tests
- Repeated measures analysis of covariance (ANCOVA) used for differences across time and between groups using education as a covariate
- Repeated measures analysis of variance (ANOVA) was used for examining differences over time from baseline to three months between groups
- Significance level set at P<0.05.
Data Collection Summary:
Timing of Measurements
- Upon enrollment, baseline data collected
- Biologic measures taken at baseline, at end of intervention (eight weeks) and four weeks post-intervention.
Dependent Variables
- Behavioral outcomes
- Diabetes knowledge: Using Diabetes Knowledge Questionnaire Spanish version (Garcia et al., 2001)
- Self efficacy: Self-Efficacy for Diabetes Scale, Spanish Version (Lorig, Ritter, & Gonzales, 2003)
- Self-management activities: Summary of Diabetes Self-Care Activities revised (SDSCA) measure (Toobert, Hampson, & Glasgow, 2000).
- Biologic outcomes
- Blood glucose
- HbA1c
- Weight
- BMI.
- Feasibility
- Ability to recruit target number of participants
- Achieve a 70% retention rate.
Independent Variables
- Level of acculturation, assessed using the Short Acculturation Scale for Hispanics (SASH)
- Age
- Gender
- Marital status
- Years of formal education
- Income
- Number of years diagnosed with diabetes.
Control Variables
Description of Actual Data Sample:
- Initial N: 20 ( 71% female)
- Attrition (final N): 17 (eight, control group; nine, intervention group)
- Age: Mean age 56, (SD=9.3, range 37-69)
- Ethnicity: Mexican American
- Other relevant demographics:
- 50% married
- Mean time since diagnosis was 7.9 years
- 76% reporting an income of less that $20,000 a year (low socioeconomic status)
- No participants had participated in a previous study in the past 12 months.
- Group Differences
- 89% of intervention group was female, 50% of the control group (P=0.08)
- Intervention group has 6.4 years of education, control group had 13.1 years of education (P=0.01).
- Location: Tucson, Arizona.
Summary of Results:
Key Findings
- Significant decrease in weight for intervention group over time
- Significant decrease in BMI for intervention group over time
- Significant change in blood glucose for intervention group over time, decreased during intervention, increased four weeks post-intervention
- Self-management activities improved for the intervention group
- Significant group-by-time interaction for self-management activities related to blood glucose P=0.00
- Significant increase in self-management activities scores from baseline to end of the intervention, then a slight decrease at four weeks post-intervention
- Significant change over time in scores for self-management activities related to exercise, P=0.002.
- Self-management activities increased significantly for the control group from baseline to end of intervention and was maintained at four weeks post-intervention
- Scores for self-management activities related to diet changed over time, P=0.002.
Intervention Group | Baseline * | Post-intervention* | Four weeks Post-intervention* |
Weight (lbs) |
175.50 (19.5) | 172.78 (17.7) | 170.56 (16.1) |
BMI | 30.62 (2.7) | 30.16 (2.2) | 29.76 (1.9) |
Blood glucose | 173.11 (60.7) | 121.44 (37.1) | 150.00 (39.9) |
Self-management activities | 3.37 (1.0) | 5.73 (0.7) | 4.97 (0.7) |
blood glucose |
0.67(1.4) | 6.69 (0.9) | 4.72 (2.6) |
exercise | 2.84 (1.8) | 5.25 (2.2) | 5.11 (1.8) |
diet (control group only) |
3.78 (1.3) | 4.25(1.0) | 5.02(1.2) |
*Measurements reported as mean and standard deviation, m (SD)
Other Findings
- Met retention rate (85%) for study feasibility
- Most successful recruitment strategy was personal phone calls made by promotora
- Weekly telephone reminders from the promotora were successful for participant retention.
Author Conclusion:
- Study achieved recruitment and retention goals
- The intervention had positive clinical and statistical effects on the outcome measures of diabetes knowledge, weight and BMI.
Funding Source:
University/Hospital: | University of Arizona College of Nursing |
Reviewer Comments:
- No blinding used in study
- Lack of difference seen between groups may be due to small sample size
- P-values not given for many results that were described as significant
- Well-written feasibility study and should influence future studies in this area.
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? | No | |
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) | N/A | |
3.2. | Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? | No | |
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")? | No | |
4. | Was method of handling withdrawals described? | Yes | |
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%.) | 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? | Yes | |
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? | No | |
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? | Yes | |
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? | Yes | |
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? | No | |
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? | No | |
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)? | No | |
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? | Yes | |
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 | |