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NC: Group vs. Individual Counseling (2007)

Citation:

Renjilian DA, Nezu A, Shermer RL, Perri MG, McKelvey WF, Anton SD; Individual versus group therapy for obesity:  Effects of matching participants to their treatment preferences. Journal of Counsulting and Clinical Psychology, 2001; 69 (4): 717-721.

PubMed ID: 11550739
 
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:
  • The primary objective was to test whether matching obese people to their preference for group or individual treatment would improve weight loss outcome
  • A secondary objective was to compare the effects of group to individual therapy.
Inclusion Criteria:
  • Adults 21 to 59 years of age
  • Body mass index of 28kg to 45kg per m2
  • Good health
  • Physician's approval to participate in the diet plus exercise weight loss intervention.
Exclusion Criteria:
  • Currently in weight loss treatment
  • Weight loss of five or more pounds within the last six months
  • Taking appetite suppressant medication
  • Pregnant or planning to become pregnant
  • Unwilling to accept random assignment to either individual or group treatment
  • Did not have a moderate to strong preference for either individual or group treatment.
Description of Study Protocol:

Recruitment

Newspaper advertisements. 

Design

  • Participants were stratified on the basis of preference for group or individual weight loss treatment and then randomly assigned to receive either their preferred or non-preferred modality
  • The major outcomes measured were weight and BMI
  • Secondary measures included psychological functioning
  • Participants also completed post-treatment ratings of adherence to behavioral treatment techniques and ratings of therapist effectiveness.

Blinding Used

Therapists (doctoral candidates) and supervisors (licensed psychologists experienced in behavioral treatment of obesity) were blinded to participants' preferences for treatment modality. 

Intervention

  • 26 weekly sessions of individual or group standard cognitive-behavioral weight management training (e.g. self-monitoring, goal-setting, stimulus control, etc)
  • Participants were instructed to follow low-calorie diet (1,200kcal per day for women and 1,500kcal per day for men) and to exercise six days per week (30 minutes per day of brisk walking). 

Statistical Analysis

  • Preliminary analyses of variance (ANOVA) to determine if there were differences in baseline measures
  • Multi-variate analysis of variance on outcomes
  • ANOVA on participants' ratings of therapist effectiveness at post-treatment.
Data Collection Summary:

Timing of Measurements

Baseline and at 26 weeks (end of treatment).

Dependent Variables

  • Variable One: Weight-related variables
    • Weight measured on balance beam scale
    • Height measured on balance beam scale stadometer
    • BMI calculated.
  • Variable Two: Psychological functioning
    • General Severity Index of SCL-90-R.
  • Variable Three: Psychological Functioning
    • Beck Depression Inventory.

Independent Variables

  • Self-reported caloric intake
  • Participant rating of therapist effectiveness, post-treatment.

Control Variables

  • Preference for group or individual treatment
  • Attendance rates for completers.
Description of Actual Data Sample:
  • Initial N: 75 adults (14 men and 61 women)
  • Attrition (final N): 58 (23% attrition rate)
  • Age: 25 to 59 years
  • Ethnicity: Not given
  • Anthropometrics: Weights and BMIs were similar for all groups (average, 94.79kg to 99.5kg per m2 and 35.4kg to 37.72kg per m2)
  • Location: Outpatient setting, location not given.
Summary of Results:

Variables

Group Treatment (Preferred)

Group Treatment (Non-Preferred)

Individual Treatment (Preferred)

Individual Treatment (Non-Preferred)

Statistical Significance of Group Difference

Weight -10.85±4.06 -11.19±5.60 -8.48±3.00 -9.61±4.17 Group vs. individual: P=0.016

Body Mass Index

-4.11±1.57

-4.25±2.11

-3.60±1.05

-3.47±1.20

Pref vs. type: NS

Psychological Functioning (General Severity Index)

-9.13±9.61

-13.21±6.76

-6.38±8.63

-0.08±7.47

Group vs. individual: NS

Pref vs. type: NS

Psychological Functioning (Beck Depression Inventory)

-5.34±4.97 -4.93±4.98 -3.31±3.97 -3.62±3.45 Group vs. individual:  NS

Pref vs. type: NS

Other Findings

  • Clinically significant weight loss (≥10% body weight) was acheived by 18 of 40 participants in the group treatment condition and by 10 of 35 participants in the individual treatment condition
  • Psychological functioning on both the General Severity Index and the Beck depression index significantly improved over time for all groups, but there was no significant difference between groups
  • Self-reported caloric intake during Weeks 12 and 24 showed a significant decrease in caloric intake for the group treatment condition but a non-significant increase for the individual treatment condition
  • Participants' ratings of therapist effectiveness was significantly greater for individual vs. group treatment (P<0.01).
Author Conclusion:
  • The results of this study failed to support the hypothesis that matching participants with their therapy preference would provide weight loss: Both types of treatment produced significant reductions in body weight
  • The significant difference between the group and individual treatment conditions is unlikely to be clinically significant. However, the finding of equivalent, if not superior weight loss benefits for group vs. individual treatment argues for the use of the group approach as a lower cost, desirable first line of clinical care
  • A major limitation to this study was that effects were measured at post-treatment time only
  • Follow-up data was not available to assess the long-term maintenance of changes in each of the treatment conditions. 
Funding Source:
University/Hospital: Marywood University, University of Florida, Hahnemand University
Reviewer Comments:
  • This was a very interesting study which showed that group treatment for obesity was more effective than individual therapy, even when the participant preferred individual therapy. This correlates with the self-reported adherence to diet; the group treatment participants reported more of a decrease in caloric intake than did the individual treatment participants.
  • In spite of better self-reported dietary adherence and greater weight-loss, the group treatment participants rated the therapist effectiveness as lower than did the individual treatment participants
  • This study affirms that lower-cost group treatment is a cost-effective weight-loss therapy
  • It does not show which treatment is most effective for long-term maintenance of weight-loss.
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? 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? ???
  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? 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? N/A
  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? N/A
  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)? No
  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? ???
  10.1. Were sources of funding and investigators' affiliations described? No
  10.2. Was the study free from apparent conflict of interest? Yes