EAL

SSPSM: Compliance (2014)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To test whether a free prepared meal and incentivized structured weight loss program promotes greater weight loss and weight loss maintenance at two years, compared with usual care.

Inclusion Criteria:

Age 18 years or older
BMI of 25kg/m² to 40kg/m² and a minimum of 15kg over ideal weight, as defined by the 1983 Metropolitan Life Insurance tables
Not pregnant or breastfeeding or planning to become pregnant in the next two years
Willing to participate in any of the three study groups over a two-year period
No eating disorders, food allergies or intolerances
Willing and able to perform a simple step test for assessing cardiopulmonary fitness.

Exclusion Criteria:

Males
BMI over 40kg/m²
Current active involvement in another diet intervention study or organized weight loss program
Having a history or presence of a significant psychiatric disorder or any other condition that, in the investigator’s judgment, would interfere with participation in the trial.

Description of Study Protocol:

Recruitment

Participants were enrolled at four study sites (University of California, San Diego; University of Arizona, Tucson; University of Minnesota, Minneapolis; Center for Health Research, Kaiser Permanente Center Northwest, Portland, Oregon)
Participants were recruited using list serves and flyers distributed by the research staff at each site.

Design
Randomized controlled trial.

Blinding Used
Implied with measurements.

Intervention

Participants were randomly assigned in a 3:3:2 allocation to the center-based intervention, the telephone-based intervention or the Usual Care Group.

Participants assigned to the Center-Based or Telephone-Based Study Groups received all program materials, including free-of-charge pre-packaged prepared foods, as needed, to achieve a meal plan
- Interactions between corporate trained and supervised staff and the participants consisted of brief weekly one-to-one contacts with an in-person or telephone counselor, with follow-up telephone and e-mail contacts and Web site or message board availability
- Counselors were instructed to provide the program as designed for a regular paying client, although they were not blinded to the identity of study participants
- Free of-charge counseling sessions were offered to participants for the entire two-year period
- The diet component of the program consisted of a nutritionally adequate, low-fat (20% to 30% of energy) reduced-energy diet (typically 1,200kcal to 2,000kcal per day) that included pre-packaged prepared food items with increased amounts of vegetables and fruits to reduce the energy density of the diet
- The approach was tailored so that participants could choose regular foods when preferred
- Participants were encouraged during the initial period to follow a menu plan with pre-packaged foods, which would provide 42% to 68% of energy for those who choose not to deviate from the plan
- Over time, participants were transitioned to a meal plan based mainly on food not provided by the commercial program, although participants could choose to include one pre-packaged meal per day during weight loss maintenance
- Prepared foods and counselors were provided by Jenny Craig, Inc. (Carlsbad, California).
Participants assigned to the Usual Care Group were provided consultation with a research staff dietetics professional, who provided publicly available print material that described dietary and physical activity guidelines to promote weight loss and maintenance at baseline (after randomization) and again at six months
- Energy intake level to achieve a weight loss of 10% over a six-month period was prescribed, aiming for a deficit of 500kcal to 1,000kcal per day
- Sample meal plans based on food groups, recommendations to increase physical activity and written materials and resources for strategies and skills were provided
- This one-hour session was followed by monthly check-in via e-mail or telephone and progress and strategies were discussed in a follow-up counseling session at six months.

Statistical Analysis

Analyses of anthropometric data were conducted as intent-to-treat, using baseline value substitution as the primary approach
- We also conducted intent-to-treat analysis using multiple imputation
- Statistical significance was set at a two-sided P-value of less than 0.05 without adjustment for multiple comparisons.
The primary outcome was weight loss over time, based on an interaction between treatment group and time
- Linear mixed models (with baseline and usual care as the reference category) were used to analyze weight trajectories and other primary and secondary outcomes by group over time, including group, time and their interaction as predictors
- Models were used to test for differences by group at baseline and by time for usual care
- The interaction term modeled the intervention effect
- A subject-specific intercept representing baseline levels of the outcome was included as a random effect in each model.

Data Collection Summary:

Timing of Measurements

Anthropometric measures (height, weight, waist circumference) were collected by institution research staff (usually unblinded) at clinic visits at enrollment and every six months over a two-year period.

Dependent Variables

Weight
Waist circumference.

Independent Variables

Weight loss intervention group assignment: Center-Based, Phone-Based or Usual Care Group.

Control Variables

Timing of measurements, follow-up procedures; food provision in diet groups.

Description of Actual Data Sample:

Initial N
All Females

Center-Based: N=169
Phone-Based: N=164
Usual Care: N=113.

Attrition (Final N)

Primary end-point measured at six, 12 and 24 months, respectively
Weight data were available at 24 months for 407 women (92.1% of the study sample)
- Center-Based: N=164, 159, 151
- Phone-Based: N=162, 157, 153
- Usual Care: N=103, 101, 103.

Age
Center-Based: 44±10 years
Phone-Based: 44±10 years
Usual Care: 45±11 years.

Ethnicity
Center-Based: 67.7% white, 14.4% Hispanic, 10.8% black, 7.2% other
Phone-Based: 79.3% white, 11.0% Hispanic, 7.3% black, 2.4% other
Usual Care: 74.8% white, 16.2% Hispanic, 7.2% black, 1.8% other.

Other Relevant Demographics
Not reported.

Anthropometrics
No significant differences between groups at baseline.

Location

University of California, San Diego
University of Arizona, Tucson
University of Minnesota, Minneapolis
Center for Health Research, Kaiser Permanente Center Northwest, Portland, Oregon.

Summary of Results:

Key Findings: Weight Loss and Maintenance (intent-to-treat analysis, N=442)

Variables		Center-Based Mean (95% CI)	Phone-Based	Usual Care	Statistical Significance of Group Difference
Weight (kg)	Baseline	92.2 (90.7-93.7)	92.9 (91.1- 94.7)	91.0 (89.0-92.9)	P<0.001 interventions vs usual care
	6 months	83.0 (81.4-84.5)	84.6 (82.8-86.4)	88.1 (86.0-90.2)
	12 months	82.1 (81.3-84.6)	84.4 (82.3-86.5)	88.5 (86.3-90.8)
	24 months	84.8 (83.0-86.5)	86.6 (84.4-88.9)	89.0 (86.7-91.3)
BMI (kg/m²)	Baseline	33.8 (33.3-34.4)	33.8 (33.3 -34.3)	34.0 (33.4-34.6)	P=0.002 interventions vs usual care
	6 months	30.5 (29.9-31.0)	30.8 (30.3-31.4)	32.9 (32.2-33.6)
	12 months	30.2 (29.6-30.8)	30.7 (30.1-31.4)	33.2 (32.4- 33.9)
	24 months	31.2 (30.5-31.8)	31.5 (30.4-32.2)	33.4 (32.5-34.2)

In the intent-to-treat analysis using baseline value substitution, women in the Center-Based Group lost a mean of 10.1kg (95% CI, 9.0kg to 11.2 kg) or 10.9% (95% CI, 9.7% to 12.1%) of initial weight by 12 months and maintained an average weight loss of 7.4kg (95% CI, 6.1kg to 8.7 kg) or 7.9% (95% CI, 6.5% to 9.3%) of initial weight at 24 months
Participants in the Telephone-Based Group lost a mean of 8.5kg (95% CI, 7.2kg to 9.7kg) or 9.2% (95% CI, 7.8% to 10.6%) of initial weight by 12 months and maintained an average weight loss of 6.2kg (95% CI, 4.9kg to 7.6kg) or 6.8% (95% CI, 5.2% to 8.4%) of initial weight at 24 months
Participants in the Usual Care Group lost a mean of 2.4kg (95% CI, 1.2kg to 3.6kg) or 2.6% (95% CI, 1.4% to 3.8%) of initial weight at 12 months and maintained a loss of 2.0kg (95% CI, 0.6kg to 3.3kg) or 2.1% (95% CI, 0.7% to 3.5%) of initial weight at 24 months (P<0.001, compared with the intervention groups)
Attenuation of weight loss between 12 months and 24 months was 27% in each intervention group and 17% in the Usual Care Group (P=0.003)
Results from the multiple imputation intent-to-treat analysis were qualitatively similar to those obtained from the primary analysis
Data for women for whom weight was measured (rather than imputed) show similar differences across the groups. By study end, more than half in either intervention group [62% of Center-Based (N=103) and 56% (N=91) of telephone-based participants] had a weight loss of at least 5%, compared with 29% (N=32) of Usual Care participants (P<0.001).
More than twice the proportion of participants in the Center-Based and Telephone-Based Intervention Groups, compared with participants in the Usual Care Group [37% (N=124) vs. 16% (N=18)], had a weight loss of 10% or more of baseline weight at 24 months (P<0.001)
Both intervention groups reported improved physical (86 vs. 82; P=0.007) and mental (79 vs. 78; P=0.04) quality of life at 12 months, compared with usual care
The Eating Disorder Examination Questionnaire global scores improved from baseline to 24 months in each group (2.3 at baseline vs. 2.1 at 24 months; P=0.007), but there was no significant intervention effect
An intervention effect was seen in improved depression scores at 12 months (5.4 for the intervention groups vs. 6.0 for the Usual Care Group; P=0.01), but not at 24 months.

Author Conclusion:

A free prepared meals and incentivized structured weight loss program that promotes diet and lifestyle modification successfully facilitated weight loss and weight loss maintenance, compared with a control group.

Funding Source:

Industry:

Jenny Craig, Inc

Food Company:

University/Hospital:

UCSD School of Medicine

In-Kind support reported by Industry:

Yes

Reviewer Comments:

Authors note that the study was not powered to identify weight differences between the Center-Based and Telephone-Based Intervention Groups.

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?	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 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?		Yes
	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.)	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?	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?	N/A
	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?	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?	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