EAL

HD: Effectiveness of Nutrition Intervention Methods (2010)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To determine the effects of a culturally competent diabetes self-management intervention in Mexican Americans with type 2 diabetes.

Inclusion Criteria:

Limited previous research involvement to blood sampling and no intervention studies
Between 35 and 70 years of age
Diagnosed with type 2 diabetes after 35 years old
Two verifiable fasting blood glucose test results of 140mg per dL or more, or taking or have taken insulin or hypoglycemia agents for one or more years in the past
Willing to participate.

Exclusion Criteria:

Less than 35 years of age or older than 70 years of age
Pregnant or if they had a medical condition for which changes in diet and exercise levels would be contraindicated.

Description of Study Protocol:

Recruitment

A total of 256 individuals with type 2 diabetes were randomly selected for the intervention study from rosters of previous Starr County research studies. A total of approximately 64 subjects were recruited quarterly during 1994 and 1995 to constitute four cohorts; in each cohort, 32 individuals entered treatment groups and 32 individuals entered wait-listed groups.

Design

A prospective, randomized, repeated measures study.

Intervention

Three months of weekly two-hour instructional sessions on nutrition, self-monitoring of blood glucose, exercise and other self-care topics and six months of biweekly plus three months of monthly two-hour support group sessions to promote behavior changes through problem-solving and food preparation demonstrations
Culturally competent intervention, which included employing bilingual Mexican American nurses and dietitians from the community, utilization of videotapes filmed in Starr County showing community leaders describing their experiences with diabetes, focused on realistic health recommendations consistent with Mexican American preferences, and offered in Spanish
Intensive (52 hours over one year)
Longitudinal (follow-up for up to three years)
Community-based schools, churches, adult day health care centers, agricultural extension centers and community health clinics sites throughout the county
Designed to provide rapid, frequent feedback
Organized to obtain support from family, friends, group participants, nurses, dietitians and community workers.

Statistical Analysis

Descriptive statistics were used to characterize the sample and to summarize outcome measures before, during and after the intervention. Hierarchical linear and nonlinear modeling software was used to perform individual growth curve analysis, using multilevel modeling. The multilevel modeling consisted of two stages: A within-subject analysis to estimate the parameters of the individual growth curve and a between-subject analysis to predict differences in the growth parameters. All analyses were conducted at the 0.05 level of significance.

Data Collection Summary:

Timing of Measurements

Primary outcomes were diabetes-related knowledge and health beliefs, HbA1c, fasting blood glucose (FBG), lipids and BMI. Body weight was measured using a balance beam scale, wearing street clothes and no shoes. Height was measured using a secured stadiometer. BMI was calculated in kilograms per meters squared. Blood samples were collected at baseline and at post-intervention intervals. FBG was assessed using a desktop glucose analyzer and HbA1c was analyzed at the University of Texas at Houston. FBG and cholesterol testing was performed on site in the field office; at each data collection session, results were reviewed with individuals before the end of their examinations. Pre-breakfast and dinner blood glucose levels were measured by subjects three days per week with home monitoring devices provided by the project.

Dependent Variables

Diabetes knowledge
Health belief
HbA1c
FBG
Cholesterol
BMI

Independent Variables

Weekly education sessions and support group sessions.

Other Variables

Age and gender were treated as random and fixed variables.

Description of Actual Data Sample:

Initial N: 256 [128 experimental group, 128 one-year wait listed (control) group]
Attrition (final N): 230
Age: 35 to 70 years old
Ethnicity: Mexican American
Other relevant demographics: Ninety percent of the subjects preferred Spanish language
Location: Starr County, Texas.

Summary of Results:

Variables	Experimental Group Baseline P=0.05	Experimental Group 12 Months P=0.05	Control Group Baseline P=0.05	Control Group 12 Months P=0.05
HbA1c	11.81±3.00(N=126)	10.89±2.56 (N=112)	11.80±3.02 (N=125)	11.64±2.85 (N=112)
FBG	213.01±64.06 (N=126)	194.95±63.27(N=114)	207.12±71.41 (N=126)	210.51±66.55 (N=113)
Cholesterol	211.83±45.34(N=126)	189.88±36.35 (N=112)	203.57±48.82 (N=125)	187.64±42.66 (N=113)
Diabetes knowledge	36.23±6.17 (N=126)	42.94±4.87 (N=110)	37.30±6.28 (N=122)	40.92±4.87 (N=107)
Social support	4.05±0.96 (N=119)	4.05±1.10 (N=110)	4.07±0.93 (N=119)	4.19±0.95 (N=107)

Other Findings

At baseline there was no statistically significant difference between experimental and control groups on any of the outcomes measures. Over time, there were statistically significant differences between the two groups on HbA1c, FBG and diabetes knowledge. In the experimental group, the level of HbA1c was decreased by 1.2 percentage points at three months compared with baseline level, increased by 0.19 percentage point between three and six months, and increased by 0.09 percentage point between six and 12 months. In the control group the HbA1c level decreased by 0.58 percentage point from baseline to three months, increased by 0.98 percentage point from between three and six months, and decreased by 0.56 percentage point between six and 12 months.

In the experimental group, FBG level was decreased by 23.4mg per dL from baseline to three-month follow-up and by 4.4mg per dL from three- to six-month follow-up, and was increased by 9.7mg per dL from six- to 12-month follow-up. In the control group, FBG level was decreased by 6.1mg per dL from baseline to three-month follow-up, increased by 14.0mg per dL from three- to six-month follow-up and decreased by 4.5mg per dL from six- to 12-month follow-up.

In the experimental group, diabetes knowledge was increased by 5.2 items correct from baseline to three-month follow-up and increased by 1.5 items correct from three- to 12-month follow-up. In the control group, increases of 1.8 items correct were observed from baseline to three-month follow-up and from three- to 12-month follow-up.

Author Conclusion:

The intent of this project was to determine, from a population perspective, whether a culturally competent diabetes self-management intervention focusing primarily on diet and self-monitoring education would improve metabolic status. This study demonstrated statistically significant changes were achieved in three health outcomes: FBG, HbA1c and diabetes knowledge. We have concluded that the cost of the intervention is not a reasonable obstacle to providing the one-year intervention. One serious obstacle to providing this intervention is the availability of bilingual Hispanic nurses, dietitians and community workers. In addition, culturally competent behavioral interventions should be the focus of major national initiatives as well as future research.

Funding Source:

Government:

National Institute for Diabetes and Digestive and Kidney Diseases, The Office of Research on Minority Health, National Institutes of Health, the State of Texas

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?	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)	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?		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?	???
	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?		N/A
	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.)	???
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	???
	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?	N/A
	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?	N/A
	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?	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)?	Yes
	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?		No
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes