Pediatric Weight Management

Family-based Counseling to Reduce Childhood Overweight (2006)

Citation:

Obarzanek E, Kimm SY, Barton BA, Van Horn L L, Kwiterovich PO Jr, Simons-Morton DG, Hunsberger SA, Lasser NL, Robson AM, Franklin FA Jr, Lauer RM, Stevens VJ, Friedman LA, Dorgan JF, Greenlick MR; DISC Collaborative Research Group. Long-term safety and efficacy of a cholesterol-lowering diet in children with elevated low-density lipoprotein cholesterol: seven-year results of the Dietary Intervention Study in Children (DISC). Pediatrics. 2001 Feb;107(2):256-64.

PubMed ID: 11158455
 
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:
This study tests the long-term efficacy and safety of a cholesterol-lowering dietary intervention in children.
Inclusion Criteria:
average of the 2 LDL-C measurements was >=80th (>=111.5 mg/dL for boys and >=117.5 mg/dL for girls) and <98th (>=164.5 mg/dL for boys and girls) age- and sex-specific percentiles of the Lipid Research Clinics population
Exclusion Criteria:
Description of Study Protocol:

Design

Participants randomly assigned to DISC diet or "usual care" where educational material was provided to the parents.

Blinding used

Not described

Intervention

Dietary Component

The DISC dietary recommendations, similar to the National Cholesterol Education Program Step 2 diet,1 were: 28% of energy from total fat, <8% from saturated fat, up to 9% from polyunsaturated fat, and <75 mg/1000 kcal of cholesterol per day, not to exceed 150 mg/day.

2 individual visits were held with the nutritionist

Behavioral Component

Intervention strategies were based on social learning theory13 and social action theory including family members

In the first 6 months, 6 weekly and then 5 biweekly group sessions were led by nutritionists and behaviorists.

During the second and third years, group and individual maintenance sessions were held 4 to 6 times per year, with monthly telephone contacts between group sessions.

By the fourth year of follow-up (when subjects were teenagers), individual visits used an individualized approach based on motivational interviewing and stage of change. Two group events plus 2 individual visits were planned annually, with additional telephone contacts as appropriate

Statistical Analysis

Analysis of covariance models to test treatment differences, with sex, age at the last visit, and baseline value of the outcome variable as covariates. Wilcoxon tests were used to test for differences in treatment groups for ordered categorical variables. Significance set at p<.05.

Data Collection Summary:

Timing of Measurements

Baseline, 1 year, 3 years, mean of 7.4 years' follow-up

Dependent Variables

  • serum LDL-C
  • height
  • serum ferritin
  • serum total cholesterol
  • high-density lipoprotein cholesterol (HDL-C)
  • LDL-C/HDL-C ratio
  • triglycerides
  • red blood cell folate
  • serum retinol and zinc
  • sexual maturation
  • Body mass index

Independent Variables

A diet with 28% of energy from total fat, <8% from saturated fat, up to 9% from polyunsaturated fat, and <75 mg/1000 kcal cholesterol per day. Behavioral counseling included. Dietary intakes were measured by a method using 3 nonconsecutive 24-hour dietary recalls.

Control Variables

None mentioned

Description of Actual Data Sample:

Initial N: 663 participants randomly assigned to an intervention or usual care group. 179 boys and 155 girls in the intervention group, 183 boys and 146 girls in the usual care group.

Attrition (final N): 87.5% of participants attended the last visit

Age: 7.8 to 10.1 years for girls and 8.6 to 10.8 years for boys

Ethnicity: 86.5% of the study sample was white

Other relevant demographics: There were no baseline differences between intervention and usual care groups in age, height, weight, BMI, or serum lipid levels. A higher proportion of the intervention group than the usual care group had household income <$20 000 (15.1% vs 5.9%; P = .002).

Location: USA (multicenter study) 

Summary of Results:

Dietary Intake

Fat

  • Intervention group: Percent of energy intake from total fat and saturated fat decreased from mean baseline levels of 33.4% and 12.5%, respectively, to 28.5% and 9.8% at 1 year and remained low, averaging 28.5% and 10.2% at the last visit
  • Usual care group: Percent of energy intake from total fat and saturated fat decreased in the later years, from baseline levels of 34.0% and 12.7%, respectively, to 31.4% and 11.7% at 5 years and 30.6% and 11.3% at the last visit
  • Adjusted differences in total fat and saturated fat between the 2 groups were significant at all time points (intervention group lower, all P < .001)

Energy

  • Energy intake was 98 and 148 kcal/day (411 and 619 kJ/day) lower in the intervention than usual care group at 1 (P = .01) and 3 years (P < .001), and not different at subsequent time points.

Other Outcomes

LDL-C

  • Mean adjusted differences between the 2 groups were significant at 1 and 3 years (P < .001 and P < .02, respectively), but not at 5 years (P = .11) or at the last visit (P = .25). Results were virtually the same after imputation for missing values

HDL-C, LDL-C/HDL-C ratio or triglycerides

  • There were no differences between the 2 groups at any time point in HDL-C (except at 1 year) LDL-C/HDL-C ratio (data not shown), or triglycerides.

BMI

  • Except at 1 year, there were no differences in BMI between the 2 groups (at 1 year, intervention group BMI mean was .2 lower than the usual care group (p<.03))
Author Conclusion:
  • The intervention group reduced their self-reported mean total and saturated fat intakes at 1 year and generally maintained these lower levels, despite a decrease in intervention intensity over time. Intervention/usual care comparisons remained statistically significant for dietary total fat and saturated fat throughout the trial, although not for dietary cholesterol at the last visit.
  • The DISC intervention focused on lowering total fat, saturated, fat, and cholesterol to reduce LDL-C. Although part of the intervention, polyunsaturated fat changed very little and did not contribute to LDL-C lowering.
  • Continued intervention resulted in no difference between intervention and usual care groups in growth, sexual maturation, or nutritional adequacy, including serum ferritin level, despite differences in self-reported dietary fat intake.
Funding Source:
Reviewer Comments:

DISC intervention was not designed as a weight management program, and changes in BMI were not a primary outcome.

Strengths:

  • large N
  • multi-site
  • randomized

Limitations:

  • Self reported dietary intake
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? N/A
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%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? No
  4.4. Were reasons for withdrawals similar across groups? No
  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? No
  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? 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)? 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? 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