Increase Font Size Decrease Font Size View as PDF Print
Citation:

DeBar LL, Ritenbaugh C, Aickin M, DeBar LL, Rittenbaugh C, Aickin , Orwoll E, Elliot D, Dickerson J, Vuckovic N, Stevens VJ, Moe E, Irving LM. Youth: A health plan-based lifestyle intervention increases bone mineral density in adolescent girls. Arch Pediatr Adolesc Med. 2006 Dec; 160(12): 1,269-1,276.


PubMed ID: 17146025
Study Design:
Randomized Controlled Trial
Class:
A - Click here for explanation of classification scheme.
POSITIVE: See Research Design and Implementation Criteria Checklist below.
Research Purpose:
  • To test the efficacy of a lifestyle intervention for increasing bone mineral density (BMD) in adolescent girls initially 14 to 16 years old.
  • To improve diet and increase physical activity.
    • Dietary targets:
      • Increasing dairy consumption
      • Eating eight servings of fruits and vegetables daily
      • Decreasing soft drink intake.
    • Physical activity targets:
      • High-impact exercise
      • Strength training.
Inclusion Criteria:

  • Adolescent females
  • 14 to 16 years of age
  • Willingness (including that of parent or guardian) to participate
  • body mass index (BMI) below national median
  • Kaiser Permanente Northwest (HMO) Human Subjects Committee monitored and approved all study procedures.

 

Exclusion Criteria:
  • Anyone with any apparent contraindication to the dietary or exercise portions of the intervention, including current or past disordered eating behavior
  • Anyone less than 14 or older than 16 years of age at baseline
  • Anyone (including parent or guardian) who was not willing to participate
  • Males.
Description of Study Protocol:

Recruitment

  • Recruitment was conducted within the Kaiser Permanente Northwest is a nonprofit, group-model health maintenance organization (HMO) in the Portland, OR metropolitan region. The research center is located within the HMO, but conducts independent, public domain research. 
  • Potential participants were identified through the HMO’s electronic medical record. Health plan member contracts with the HMO provide consent for use of their data in research.
  • Members who met the selection criteria were mailed study invitations, followed by telephone calls from research staff
  • An informational meeting for interested families meeting study criteria preceded randomization.

Design

  • Randomized control trial (RCT) 
  • Treatment group assignment was made by a design-adaptive randomization to minimize group imbalance on physical activity, calcium intake, age and other factors. Design adaptive randomization sequentially assigned girls to the control or intervention groups to achieve, at each step, the maximum balance of factors predictive of bone measurements, such as menarcheal age and participation in organized sports. To conceal allocation, the project biostatistician made allocations in response to project staff requests.

Dietary Intake/Dietary Assessment Methodology

  • Certified dietary interviewers used unannounced 24-hour telephone diet recalls to obtain data on all foods consumed, preparation method and portion size. Participants were trained to estimate portion size using real food and food models at the screening visit and received visual aids for estimating portion size of various foods.
  • Data were directly entered into the ESHA database (ESHA Food Processor, version 8.1, 2003; ESHA Research Inc, Salem, Ore). Researchers limited the nutrient variables to the food group-based nutrition categories potentially relevant for bone mineral accrual [total calcium intake (mg per day); total vitamin D (IU per day); and fruits and vegetables (servings per day)]. In addition, researchers adapted the ESHA program to output soda intake in ounces per day and vitamin supplementation.

Blinding Used

The study’s project manager informed participants of group assignment to keep assessors blinded. Likewise, staff who performed clinical and dietary and physical activity assessments were masked to the experimental condition of the participants. These assessors had no additional contact with participants.

Intervention

The YOUTH intervention emphasized adolescents actively developing strategies for healthy dietary and exercise practices that they could maintain in adulthood. Participants attended group and individual meetings, participated in activities, and received coaching telephone calls. They also received psycho-educational information, recorded their diet and exercise goals and achievements and kept in touch with their cohort through a Web-based study site. This intervention combines elements especially for adolescents (peer-oriented, community-building activities) with those widely recognized as important in lifestyle interventions (individual tailoring). Further, this intervention drew heavily from both mentoring models and motivational interviewing or enhancement techniques. Because this trial involved a two-year intervention and follow-up, researchers incorporated several adherence and retention components into this program. 

  • BMD was the primary dependent variable, and the intervention effect was estimated as the adjusted (for baseline values) mean difference between the intervention and control conditions after years one and two. Researchers used a conditional change model and the Zellner seemingly unrelated regression models. This approach uses joint estimates of several regression models.
  • Baseline and change equations were estimated simultaneously because researchers expected that the two equations were not independent. Adjusting for the correlated errors generally leads to more efficient estimates of the coefficients and reduced standard errors in both equations than would result from the use of separate equation estimations.
  • All analyses were adjusted for baseline age, years since menarche, risk of adult osteoporosis, height, BMI and the respective bone mass variable
  • All significance tests were two-sided
  • Researchers used the same regression approach for secondary outcomes (changes in diet and physical activity)
  • In addition, researchers examined behavioral (overall energy intake and overall physical activity) and anthropometric factors (weight, height, BMI and lean and fat masses) that were not targeted for behavioral change.

Statistical Analysis

Statistical analyses were conducted using SAS Release 8.2 (SAS Institute Inc, Cary, NC) and STATA version 6.0 (StataCorp, College Station, Tex).

Data Collection Summary:

Timing of Measurements

  • BMD was measured at baseline and at one- and two-year follow-up
  • Dietary Intake (via unannounced dietary recall) was done six times per year (once every other month)
  • physical activity information was collected (via recall) six times per year (once every other month)
  • Strength and fitness tests were conducted at three annual clinic visits (baseline, one- and two-year follow-up)
  • Anthropometry (height, weight, body mass index) were collected at three annual clinic visits (baseline, one- and two-year follow-up).

Dependent Variable

  • BMD was the primary dependent variable
  • Secondary variables included:
    • body mass index (height and weight)
    • Biomarkers (osteocalcin and naltrexone)
    • Dietary Intakes (calorie, fruit and vegetable servings, soda consumption, calcium and vitamin D intake)
    • Weight-bearing physical activity, strength and fitness.

Independent Variable

YOUTH health care-based lifestyle intervention.

Control Variables

  • Age
  • Years since menarche
  • Risk of adult osteoporosis
  • Height
  • BMI
  • Respective bone mass variable. 
Description of Actual Data Sample:
  • Initial N: 228 teenaged girls were randomized (113 to intervention and 115 to control)
  • Attrition (final N): 209 girls were included in analysis (this was the number of girls that completed at least one year of follow-up), with 101 the intervention group and 108 in the control group
  • Age:14 to 16 years old at enrollment
  • Ethnicity: 81% white (no further description)
  • Other relevant demographics: Participants were mainly from middle- to upper middle-income working homes
  • Anthropometrics: No differences between intervention and control groups in consumption of calcium, Vitamin D, servings of fruits and vegetables, consumption of soda and total physical activity at baseline
  • Location: HMO in Portland, Oregon metropolitan area.
Summary of Results:

  • Compared to control subjects, girls in the intervention group had significantly higher BMD in the spine and trochanter regions during the first study year, which was maintained during the second study year
  • The naltrexone biomarker demonstrated a greater relative decrease in the intervention group compared with the control group, with non-significant (NS) changes in osteocalcin consistent with more bone building in the intervention group
  • Participants in the intervention group reported significantly greater consumption of calcium in both study years, vitamin D in the first year and fruits and vegetables in both years
  • No effect on soda consumption or target exercise rates was found for either group.
 

Control Group (N=108)

Intervention Group (N=101)

P-value

OUTCOME

Baseline Value

Adjusted Δ to Year One

Adjusted Δ to Year Two

Baseline Value

Adjusted Δ to Year One

Adjusted Δ to Year Two

Baseline Year One

Baseline Year Two

Bone mineral density   

Total body, g per cm2

1.114(0.008)

0.024(0.002)

0.025(0.002)

1.114(0.008)

0.027(0.002)

0.029(0.003)

0.27 0.19 

Spine, g per cm2

0.973(0.009)

0.017(0.002)

0.033(0.003) 

0.962(0.010)

0.029(0.002)

0.045(0.003) 

<0.001  0.007 

Trochanter, g per cm2

0.775(0.010)

0.003(0.002)

0.003(0.003)

0.763(0.011)

0.010(0.002)

0.013(0.003)

0.3  0.3 

Biomarker

Osteocalcin, ng per ml

17.932(0.715) 

 

-5.597(0.438)

19.214(1.006) 

 

-5.57(0.420)

  0.95 

Nalterxone, nM BCE

36.462(2.024)

 

-11.163(0.618) 

37.024(1.825) 

 

-13.211(0.610) 

  0.2 
Diet        

Calcium, mg per day

977.43(38.78)

-64.41(38.41) 

-13.72(39.27) 

994.37(46.70) 

152.21(39.72) 

227.56(41.35)

<0.001  <0.001

Vitamin D, IU per day

157.01(11.28)

2.95(10.33)

54.03(0.16)

166.42(14.13)

37.27(10.68)

86.13(14.49) 

0.02  0.11 

Fruits and Vegetables

3.53(0.21)

0.01(0.18)

0.16(0.21) 

3.68(0.24) 

0.74(0.19) 

0.95(0.22)

0.005  0.01 
Soda (oz)

5.20(0.69)

-0.05(0.47)

-0.98(0.38)

5.13(0.69)

-0.95(0.48)

-1.24(0.40)

0.18 0.65 

 

Author Conclusion:

A comprehensive health care-based lifestyle intervention can effectively improve dietary intake and increase bone mineral gains in adolescent girls. This study is the first (to the authors’ knowledge) to significantly improve bone mass in adolescent girls in a non-school-based intervention.

Reviewer Comments:

Authors limitations:

  • The study was not power to obtain significant findings for the Web elements and as such, the results should be viewed as hypothesis-generating rather than hypothesis testing
  • Participants appeared to have over-self-reported minutes-per-week of Web site use
  • Demographics of the study may limit generalization. Web usage might have been different in a broader population. Participants came from well-resourced households, higher education and SES class

Research Design and Implementation 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 nutrition or dietetics practice?
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?
Yes
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 used? (Concurrent preferred over historical controls.)
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 or cross-sectional 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. Criterion may not be applicable in some cross-sectional studies.)
N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?
Yes
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?
Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?
Yes
  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.)
Yes
  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?
Yes
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?
???
  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?
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?
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)?
No
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?
N/A
  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