EAL

SSPSM: Compliance (2014)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To test whether a weight loss program promotes greater weight loss, glycemic control and improved cardiovascular disease risk factors compared with control conditions and whether there is a differential response to higher vs. lower carbohydrate intake.

Inclusion Criteria:

History of type 2 diabetes confirmed by a physician
Aged at least 18 years
BMI of 25kg/m² to 45kg/m²
Not pregnant or breastfeeding or planning to become pregnant in the next year
Willing to participate in any of the study diet arms over a one-year period
No eating disorders, food allergies or food intolerances
No history of bariatric surgery
Willing and able to perform a step test for assessing cardiopulmonary fitness.

Exclusion Criteria:

Current active involvement in another diet intervention study or organized weight loss program
Weight loss of more than 10 lbs in the past three months
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 disqualified participants
HbA1c over 11% (97mmol per mol), fasting triglyceride level over 600mg per dL and serum creatinine level of 1.4mg per dL or more in females or 1.5mg per dL or more in males.

Description of Study Protocol:

Recruitment

Men and women were recruited and enrolled at two study sites [University of California, San Diego (UCSD); University of Minnesota, Minneapolis]
Participants were recruited through word-of-mouth, direct marketing letters mailed to large cohorts, radio advertisements, local e-mail subscription services, ClinicalTrials.gov, social media and flyers.

Design
Randomized controlled trial.

Blinding Used
Implied with measurements.

Intervention

Participants were randomly assigned to a weight loss program with a higher carbohydrate, lower fat (LF) diet plan; a weight loss program with a lower carbohydrate, higher fat (LC) diet plan; or a UC program
Participants in the two commercial weight loss program arms of the study received weight loss counseling and all program materials free of charge, including pre-packaged foods. Three entrees and one to two snacks were provided for seven days per week during the initial weight loss phase (Months One through Six) and for five days per week during a transition phase (Months Seven through Nine) and one entree and one snack daily was provided, as desired, during the maintenance phase (Months 10 through 12)
Participants were encouraged, especially during the initial period, to follow the menu plan with pre-packaged foods (41% to 76% of energy)
The pre-packaged foods provided more than one-half to two-thirds of energy intake for most participants and somewhat less for those at higher levels of dietary energy prescription during the initial period
Participants in the Usual Care Group received two weight loss counseling sessions and monthly contacts.

Statistical Analysis

Weight change, the primary study outcome, was analyzed as intention to treat, with baseline substitution for missing data
Change over time was examined in longitudinal mixed models, based on an interaction between study group and time and controlled for sex.

Data Collection Summary:

Timing of Measurements

At data collection clinic visits, weight, waist circumference, height (baseline only) and blood pressure were measured by institution research staff who usually were unblinded
One-to-one counseling sessions with trained program staff were offered for the one-year period, with follow-up telephone and website or message board availability
Weekly counseling visits were recommended during the first nine months, after which participants had the option to move from weekly to bi-weekly or monthly consultations.

Dependent Variables

Weight and height
Waist circumference
Blood pressure.

Independent Variables

Weight Loss Intervention Group assignment: LF diet, LC diet or UC Program.

Control Variables

Timing of measurements
Follow-up procedures
Food provision in commercial diet groups (LF and LC).

Description of Actual Data Sample:

Initial N

LF diet: N=74; 52.7% males, 47.3% females
LC diet: N=77; 52% males, 48.1% females
UC program: N=76; 42.1% males, 57.9% females.

Attrition (Final N)
Primary end-points measured at three, six and 12 months, respectively.

LF diet: N=73, 72, 69
LC diet: N=76, 74, 67
UC program: N=69, 64, 68.

Age

LF diet: 55.5±9.2 years
LC diet: 57.3±8.6 years
UC program: 56.8±9.3 years.

Ethnicity

LF diet: 79.7% white; 9.5% African-American; 5.4% Hispanic; 5.4% Asian; 0% other
LC diet: 81.8% white; 2.6% African-American; 7.8% Hispanic; 5.1% Asian; 2.6% other
UC program: 77.6% white; 5.3% African-American; 9.2% Hispanic; 2.6% Asian; 5.3% other.

Other Relevant Demographics
Not reported.

Anthropometrics
No differences between groups at baseline in BMI or other variables.

Location
UCSD, San Diego, CA, and U Minnesota, Minneapolis, MN, USA.

Summary of Results:

Key Findings -
Weight Loss and Maintenance

Variables		LF Diet	LC Diet	UC Group	Statistical Significance of Group Difference
Weight (kg)	Baseline	105.4±17.8	106.4±18.3	104.6±16.9	0.87
	6 months	96.5±17.5	95.0±17.9	102.2±17.3	<0.001
	12 months	97.7±18.0	96.7±19.7	101.9±17.4	0.005
Weight change (%)	6 months	-8.6±5.9	-10.4±6.9	-2.3±4.2	<0.001
Weight change (%)	12 months	-7.4±7.6	-9.0±8.4	-2.5±5.5	<0.001
BMI (kg/m²)	Baseline	36.2±4.3	36.2±4.7	36.3±4.4	0.86
	6 months	33.2±4.4	32.4±4.8	35.5±4.7	<0.001
	12 months	33.5±4.7	33.0±5.5	35.4±4.6	0.001

At baseline, mean (±SD) weight was 105.5±17.6kg
Relative weight loss was 7.4% (95% CI, 5.7% to 9.2%), 9.0% (7.1% to 10.9%) and 2.5%
(1.3% to 3.8%) for the Lower Fat, Lower Carbohydrate and UC Groups (P<0.001 intervention effect)
At six months, those in the LF Group had reduced initial weight by 8.6% (95% CI, 7.2% to 10.0%), those in the LC Group by 10.4% (8.9% to 12.0%) and those in UC Group by 2.3% (1.3% to 3.2%)
Participants in the intervention arms lost more weight than those in the UC arm: 10.3kg (95% CI, 9.2kg to 11.5kg) vs. 2.8kg (1.6kg to 4.1kg); P<0.001
At study end, maintained weight loss was greater in the intervention arms (8.2% of initial weight) than in the UC arm (2.5% of initial weight, P<0.001)
The LF and LC Groups did not differ in weight loss at 12 months in the intention-to-treat analysis, although among the completers, LC lost more weight than LF (10.2% vs. 7.9%, P=0.035)
A majority (86 of 149) of participants in the weight loss program maintained at least a 5% loss of initial body weight at study end, compared with less than one quarter (18 of 76) of UC participants (P<0.001)
At study end, a weight reduction of at least 10% was achieved by 38% of the weight loss program participants (57 of 149) and 9% of the UC participants (seven of 76, P<0.001)
Glycemic control markers and triglyceride levels were lower in the intervention groups, compared with the UC Group at one year: Fasting glucose, 141mg per dL (95% CI, 133mg to 149mg per dL) vs. 159mg per dL (144mg to 174mg per dL), P=0.010; hemoglobin, A1c 6.9% [6.6% to 7.1%] vs. 7.5% [7.1% to 7.9%] or 52mmol per mol (49mmol to 54mmol per mol) vs. 58mmol per mol (54mmol to 63mmol per mol), P=0.001; triglycerides, 148mg per dL (134mg to 163mg per dL) vs. 204mg per dL (173mg to 234mg per dL), P<0.001
The lower vs. higher carbohydrate groups maintained lower hemoglobin A1c: 6.6% (95% CI, 6.3% to 6.8%) vs. 7.2% (6.8% to 7.5%) or 49mmol per mol (45mmol to 51mmol per mol) vs. 55mmol per mol (51mmol to 58mmol per mol) at one year (P=0.008)
After six months, there were differences among groups in terms of mental quality-of-life scores, but weight loss program participants had lower depression scores (five vs. seven, P=0.009) and better physical quality-of-life scores (80 vs. 72, P=0.005) than participants in the Usual Care Group.

Author Conclusion:

The structured weight loss program resulted in greater weight loss in overweight or obese individuals with type 2 diabetes, compared with a UC Control Group receiving less intensive counseling.

Funding Source:

Industry:

Jenny Craig, Inc

Food Company:

University/Hospital:

UCSD School of Medicine

In-Kind support reported by Industry:

Yes

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?	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?	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?	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?	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