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HD: Effectiveness of Nutrition Intervention Methods (2010)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

The purpose of this study was to estimate the effects of adding a formal faith-based component to a culturally tailored weight loss intervention on weight loss, dietary fat consumption, and physical activity.

Inclusion Criteria:
  • Self-identified as African-American or black
  • Female
  • Older than 21 years
  • BMI more than 25kg/m2
  • Not currently pregnant or nursing
  • No current illegal drug use
  • Reported consumption of no more than two alcoholic beverages per day
  • No medical problems that would restrict or prohibit moderate physical activity
  • No cancer that required treatment in the last five years (except skin cancers other than melanoma)
  • Agreed to randomization
  • Not planning to move from the Chicago area within the time frame of the intervention
  • Able to attend scheduled classes.

Furthermore, medical approval required when participant:

  • Positively endorsed two or more questions on the Physical Activity Readiness Questionnaire (a screening tool for entry into low-to-moderate-intensity physical activity programs)
  • Reported diabetes
  • Reported serum cholesterol levels ≥300mg/dL, or
  • Had a systolic blood pressure ≥160mm Hg or a diastolic pressure ≥100mm Hg.
Exclusion Criteria:

Those not meeting inclusion criteria and those not cleared medically

Description of Study Protocol:

Recruitment

  • Recruitment done at the John H. Stroger, Jr. Hospital of Cook County in Chicago
  • Patients, staff and visitors were recruited in the hospital cafeterias and through flyers and posters advertising the program throughout the hospital.

Design

  • Randomized controlled design
  • After baseline visit, eligible participants were randomized into one of two groups:
    • Culturally tailored weight loss group (control group)
    • Faith-based, culturally tailored weight loss group (intervention group)
  • Data were collected at baseline and at the end of the program (12 weeks).

Intervention

  •  Culturally tailored weight loss program (control):
    • Small group sessions, met twice weekly for 12 weeks
    • First 90-minute weekly meeting was divided between a 45-minute interactive didactic component and a 45-minute exercise component
    • Second weekly meeting consisted of a 45-minute exercise session
    • Incorporated healthy ways of preparing traditional black food
    • Emphasized family and social support
    • Offered childcare
    • Discussed multiple family obligations and provided advice on how to prepare healthy food when serving a large extended family
    • Shared stories that involved well-known or historical figures
  • Faith-based weight loss program (intervention):
    • Identical to culturally-tailored program but also addressed faith or spirituality issues in a structured and systematic manner
    • Scripture incorporated into the content of the intervention each week
    • Faith-based component delivered by a woman with extensive experience conducting health risk reduction interventions with minority populations and a thorough knowledge of the Bible and scripture readings.

Statistical Analysis

  • Differences in baseline characteristics between groups were tested using Student's T-tests or Wilcoxon rank sum tests for continuous variables and Chi-squared tests for categorical variables
  • To compare changes from baseline to follow-up in the faith-based and culturally-tailored weight loss groups, T-tests and Wilcoxon rank sum tests used
  • 95% confidence intervals for the differences between the two groups were computed
  • Effect size was estimated as a percentage of the pooled within-group standard deviation of the change in the outcome variable
  • Changes from baseline to follow-up within groups were tested using one-sample T-tests.
Data Collection Summary:

Timing of Measurements

Baseline and 12 weeks

Dependent Variables

  • Body mass index (BMI) in kg/m2: Computed from weight and height, with height measured using a stadiometer and weight measured using a digital scale, with participants wearing light clothes and no shoes; only height was measured at baseline 
  • Physical activity: Energy expenditure estimated with use of the Stanford Seven-Day Physical Activity Recall (7D-PAR)
  • Percent of energy from fat: Estimated with the Percent Energy from Fat Screener developed at the National Cancer Institute.

Independent Variables

 Treatment (control vs. intervention)

 Other variables assessed but neither dependent nor independent variables:

  • Demographics (age, education, income, employment, marital status)
  • Duke Religion Index
  • Santa Clara Strength of Religious Faith
  • Daily Spiritual Experience
  • Breast health behavior.

 

Description of Actual Data Sample:
  • Initial N:
    • 145 completed an eligibility interview (45 ineligible, 32 dropped out before completing baseline visit)
    • 68 women completed baseline visit (eight ineligible, one dropped out before randomization)
    • 59 women randomized:
      • 30 to intervention
      • 29 to control
    • 52 began intervention (seven withdrew or were lost to follow-up prior to the first intervention session)
      • 27 in intervention group
      • 25 in control group
  • Attrition (final N): 46 completed 12-week follow-up visit (88% of those who began intervention) 
    • 23 in intervention group
    • 23 in control group
  • Age: Mean in years (standard deviation):
    • Intervention group: 47.8 (10.3)
    • Control group: 49.1 (11.6)
  • Other relevant demographics: No significant difference at baseline between groups in:
    • Education
    • Income
    • Full-time work
    • Marital status
    • BMI
    • Weight
    • Percent of calories from fat
    • Energy expenditure
    • Moderate activity
    • Vigorous activity
    • Duke Religion Index
    • Santa Clara Strength of Religious Faith Questionnaire
    • Daily Spiritual Experience Scale
  • Anthropometrics: Mean BMI in kg/m2 (standard deviation)
    • Intervention group: 39.3 (7.4)
    • Control group: 38.4 (7.3)
    • Mean weight in kg (standard deviation)
      • Intervention group: 103.7 (20.6)
      • Control group: 103.0 (18.5)
    • Mean percent of calories from fat (standard deviation)
      • Intervention group: 35.8 (6.0)
      • Control group: 34.7 (6.3)
    • Mean energy expenditure in kcal per kg per day (standard deviation)
      • Intervention group: 35.6 (4.5)
      • Control group 33.9 (2.1)
    • Mean moderate activity in kcal per kg per day (standard deviation)
      • Intervention group: 3.9 (4.3)
      • Control group: 2.2 (2.4)
    • Vigorous activity in kcal per kg per day (standard deviation)
      • Intervention group: 1.3 (2.6)
      • Control group: 0.4 (1.2)
  • Location: Chicago, Illinois.

 

Summary of Results:

Key Findings

Both groups had a significant change in BMI and weight. Although the treatment group had a greater change in BMI and weight on average than the control group, the difference between groups was not statistically significant. The estimated effect size for change in BMI was 0.27 (27% of the standard deviation of change in BMI).

Percent of calories from fat was lower at follow-up in both groups, but the change was not statistically significant based on T-test results. The Wilcoxon signed rank test did show a significant (P<0.05) decrease for both groups. The difference between groups was not statistically significant.

Only the control group experienced a statistically significant increase in physical activity (energy expenditure, moderate activity and vigorous activity). The difference between groups was not statistically significant.

  Baseline    12-Week Follow-up 

 Difference (Treatment-Control)

(95% CI)

 Pa

Treatment Group

Mean (SD)

Control Group

Mean (SD)

Treatment Group

Mean (SD)

Control Group

Mean (SD)
BMI (kg/m2)

39.9 (8.1)

 39.3 (7.5) 39.0 (8.1)  38.7 (7.7)     
Weight (kg) 105.6 (20.7) 105.0 (18.2) 103.0 (20.7) 103.4 (19.0)     
BMI change (kg/m2)     -1.0 (1.3)** -0.6 
(1.2)*		 -0.34 
(-1.08 to 0.41)		 0.37 
Weight change (kg)     -2.6 (3.5)** -1.6
(3.2)* 		 -0.95 
(2.94 to 1.04) 		 0.34 
Weight change (percent)     -2.4 (2.9)*** -1.7
(3.1)* 		 -0.73
(-2.52 to 1.06) 		 0.41 
Dietary fat (percent of kcal) 36.1 (6.2)  35.4 (6.4) 33.3 (5.1) 32.7 (6.1)  -0.25
(-4.45 to 3.95) 		 0.91 
Energy expenditure (kcal per kg per day) 35.9 (5.1) 33.4 (1.8) 36.2 (3.3) 37.0 (6.0)**  -3.26
(-6.91 to 0.40) 		 0.08 
Moderate activity (kcal per kg per day) 3.9 (4.8)  1.7 (2.0) 2.8 (2.7) 3.4 
(3.5)*		 -2.80
(-5.69 to 0.09) 		 0.06 
Vigorous activity (kcal per kg per day) 1.8 (3.0)  0.4 (1.3) 3.0 (3.3) 3.0 
(6.1)*		 -1.42
(-4.54 to 1.69) 		 0.36 

Significantly different from zero, from one-sample T-test: *P<0.05; ** P<0.01, ***P<0.001

a From two-sample T-test, with change from baseline to follow-up as the dependent variable

SD=standard deviation; CI=confidence interval

 

 

Author Conclusion:

Overall, the results of this pilot study show that there may be benefit to adding a faith component to our previously tested culturally based weight loss intervention. The observed effect size of 0.27 for BMI was much smaller than the effect size for our previous study that tested a culturally tailored weight loss intervention compared to a standard control group (approximately 116%). However, given that we were testing two active interventions, we did not expect a difference as dramatic as that. A future adequately powered trial can provide more definitive results. 

Funding Source:
Government: National Institutes of Health
Not-for-profit
Avon Foundation
Foundation associated with industry:
Reviewer Comments:

The authors suggest that their study is not adequately powered to show statistically significant results, but they do not give the results of a power analysis. I question their statistical methods, wondering if a mixed-design ANOVA (with one repeated measure factor and one between groups factor) would have been more appropriate. However, perhaps the authors did not believe they had a large enough sample size for this method. I think given that the groups were not significantly different on any of the outcome measures, the authors may be taking a leap saying the faith component may add some benefit to the culturally-based weight loss intervention. Certainly they are correct that a larger trial would be necessary to give more definitive results. 

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) ???
  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? 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? ???
  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? 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? N/A
  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? ???
  6.6. Were extra or unplanned treatments described? ???
  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? 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? ???
  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? ???
  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)? 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? No
9. Are conclusions supported by results with biases and limitations taken into consideration? ???
  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