• Increase Font Size
  • Decrease Font Size
  • View as PDF

NC: Maintenance of Health/Behavior Change Following Short-term CBT (2008)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

Overall Goal

Provide further understanding of the maintenance problem by focusing on repeated measures of outcome in a well-defined population

  1. Provide descriptive information about the course of weight regain over time among individuals with different characteristics
  2. Study patterns of weight loss and gain, which might have important clinical or theoretical implications.
Inclusion Criteria:

Participation in one of two controlled weight-loss trials conducted earlier (1980 to 1981).

Exclusion Criteria:
None discussed.
Description of Study Protocol:

Recruitment

Subjects in the present follow-up study were participants in one of two controlled weight-loss trials previously conducted. 

Design

  • Descriptive follow-up of previously conducted controlled weight-loss trials
  • Subjects were assessed before and after treatment and at one-year intervals thereafter
  • This report covers five years of follow-up for Study One and four years for Study Two
  • For comparison, all other outpatient behavioral studies the authors could locate with follow-ups of two years or more (11 studies) were included

[Both initial studies employed a 15-week behaviorally-oriented program including diet and exercise instruction, behavioral skills training, cognitive behavior modification and relapse prevention training. There were financial contracts for weight loss.]

Statistical Analysis

Overview

  • Weight change expressed as a percentage of initial body weight
  • In examining the effects of gender, prior program experience and other variables on outcome, repeated-measures analysis of variance supplemented with correlational and mean comparisons as appropriate
  • To examine individual patterns of weight change and frequency of different outcomes of theoretical interest.

Detailed

  1. Descriptive statistics (N, percentage female, treatment length, initial weight and percentage overweight, age, post-treatment net weight loss, net weight loss at one, two, three, four and five years, if data available)
  2. Means, SDs and ranges and ranges for weight losses and means and SDs for baseline and follow-up variables for men and women for the variables of:
    • Net weight loss (kg) post-treatment, one, two, three and four years
    • Pre-treatment weight (kg)
    • Pre-treatment overweight (percentage)
    • Percentage with prior program experience
    • Age (years)
    • Age of onset (years)
    • Diet methods (mean per year)
    • Techniques (mean per year).
  3. Repeated-measures ANOVA of changes in percentage of initial body weight for gender
  4. Repeated-measures ANOVA of sex by prior program experience
  5. Repeated-measures analyses of weight changes in the quartiles of initial loss and follow-ups for gender
  6. Correlation; variables of:
    • Net weight loss (kg) post-treatment, one, two, three and four years
    • Pre-treatment weight (kg)
    • Pre-treatment overweight (percentage).
  7. Percentages of men and women maintaining different amounts of initial loss cumulatively over time and at each follow-up
  8. Correlations between the three variables of age of onset, use of techniques and numbers of post-treatment diets to weight outcomes
  9. Correlations between subjects obese before age 20, compared to those who became obese after age 20 and subjects high or low, according to a median split of number of techniques and diets were compared
  10. Repeated-measures analysis for age of onset and sex
  11. Repeated-measures ANOVA for use of techniques and sex
  12. Patterns of weight change
    1. Frequency of continued loss
    2. Stable maintenance
    3. Yo-yo gain and loss
    4. Other patterns distinct from the average pattern of monotonic regain
    5. Meaningful weight change defined as a gain or loss of 2.5% of initial body weight.

Data Collection Summary:

Timing of Measurements

  • Treatment year, one, two, three, four and five years' follow-up
  • Patterns of weight loss for four years only.

Dependent Variables

  • Variable One: Weight change
  • Variable Two: Patterns of weight change.

Independent Variables

For the various tests (not all variables used for each test)

  • Variable One: Gender
  • Variable Two: Prior program experience
  • Variable Three: Pre-treatment weight (kg)
  • Variable Four: Pre-treatment overweight (percentage)
  • Variable Five: Age (years)
  • Variable Six: Age of onset (years)
  • Variable Seven: Diet methods (mean per year)
  • Variable Eight: Techniques (mean per year).
Description of Actual Data Sample:

Initial N

152 (114 men, 38 women).

Attrition (Final N)

  • For the variables of net weight loss post-treatment, one year, two to four years, pre-treatment weight, pre-treatment overweight percentage: No attrition
  • For the variable percentage with prior program experience: 134 (102 men, 32 women)
  • For the variable age: 141 (106 men, 35 women)
  • For the variable age of onset: 141 (107 men, 34 women)
  • For the variable diet methods: 100 (67 men, 33 women)
  • For the variable techniques: 120 (86 men, 34 women).

Age

  • Men: 51.2 years
  • Women: 47.8 years.

Ethnicity

Not reported.

Other Relevant Demographics

  • Pre-treatment overweight percentage
    • Men: 41.3%
    • Women: 37.6%.
  • Age of onset of obesity
    • Men: 24.9 years
    • Women: 23.9 years.

Anthropometrics

  • Pre-treatment weights
    • Men: 101.1kg
    • Women: 83.1kg.
  • No standard comparison group.

Location

Clinic or self-report via phone.

Summary of Results:

Table One: Long-Term Follow-Ups of Behavioral Weight-Loss Programs

Present
Studies
Initial N
Percentage
Female
Treatment
Length
(Weeks)
Initial
Weight
(kg), Percentage Overweight
Age
Net Weight Loss (kg), N
Post
One Year
Two Years
Three Years
Four Years
Five Years
Study A
89
0
15
100.5, 44.6
52.8
13.0, 89
7.4, 86
5.0, 88
4.2, 85
3.0, 81
2.5, 83
Study B
113
51
15
94.4, 50.2
47.8
10.0, 107
5.8, 108
3.5, 103
4.1, 86
2.8, 84
 
  
Table Two: Means, SDs and Ranges for Weight Losses and Means and SDs for Baseline and Follow-Up Variables
N=114 for men and N=38 for women unless otherwise noted
 
 
Men
Women
Net Weight Loss (kg)
Post-treatment
13.0 (5.2; -0.9,29.5)
8.6 (3.8; 1.7, 17.9)a
One year
7.3 (6.4; -11.9,29.1)
6.5 (6.5; -1.8, 23.6)
Two years
5.2 (6.6; -19.4,23.5)
4.3 (5.6; -3.7, 22.4)
Three years
4.4 (6.3; -18.9, 20.0)
4.5 (5.5; -4.8, 21.8)
Four years
2.8 (6.3; -21.2, 18.5)
4.0 (5.8; -4.3,18.6)
 
  • Sex-specific repeated-measures analyses of weight change in the quartiles (treatment year, one year post-treatment, two to five years post-treatment) indicated significant effects for quartile and time in both sexes (P<0.001), but a significant quartile by time interaction for women only (P<0.001)
  • For women, pre-treatment weight and percentage overweight were negatively related to percentage of initial body weight lost in treatment (R=-0.42, P<0.01) and percentage overweight was also negatively related to weight gain in the first year of follow-up (R=-0.35, P<0.05)
  • For men, initial weight and percentage overweight were not related to short- or long-term outcome. Weight-loss in treatment was strongly related to net weight loss at four years (R=0.59 P<0.001).

Maintenance Patterns

  • Men: Recovery from relapse was unusual and monotonic regain was the predominant pattern
  • Women: A sizable proportion of women showed some degree of renewed weight loss after a period of regain.

Relationships of Age of Onset, Use of Techniques and Numbers of Post-Treatment Diets to Weight Outcomes

  1. Correlations between the three variables and weight outcomes were computed separately by gender:
    • Self-reported use of techniques were related to better long-term outcomes for both men (R=0.24, P<0.05) and women (R=0.53, P<0.01)
    • Number of techniques was related to first-year gain for women (R=-0.48, P<0.01), but not for men
    • Number of post-treatment diets did not show a relationship with outcome for either sex
    • Age of onset, while not related to outcome for males, was weakly related to weight gain in the first year (R=-0.40, P<0.08) and significantly related to net weight loss (R=-0.40, P<0.05) for women.
  2. Subjects obese before age 20 were compared to those who became obese after age 20 and subjects high or low, according to a median split of number of techniques and diets were compared
    • Women who became obese at younger ages had higher net weight losses after four years and gained less in the first year of follow-up
    • For women, age was negatively related to net weight loss at four years (R=-0.36, P<0.05). Further analysis indicated that in women, age and age of onset were significantly correlated (R=0.54, P<0.01) and therefore, correlations of age and onset adjusted for each other were also calculated. Age of onset adjusted for age at the time of treatment remained significantly related to net loss at four years (R=-0.34, P<0.05), while age at treatment adjusted for age of onset did not.
    • Repeated-measures analysis for age of onset indicated significant effects for time (P<0.0001) and sex by time (P<0.001). In men, subjects obese before age 20 showed a nearly identical outcome to subjects becoming obese after age 20. In women, the younger-onset subjects lost more weight initially and maintained that superiority throughout follow-up.
    • For use of techniques, repeated-measures ANOVA indicated significant time (P<0.0001), technique (P<0.05) and technique x sex (P<0.001) effects
    • No impact of number of post-treatment diets was found.

Patterns of Weight Regain

  • For men and women, respectively, 0.9% and 5.3% showed stable maintenance, 3.5% 10.5% showed significant recovery from relapse and 10.5% 7.9% appeared to yo-yo
  • In men, approximately 70% showed a pattern of monotonic increase in weight regain over follow-up, while 15.8% had a pattern of regain interrupted by a single weight loss. For women, the comparable percentages were 36.8% 41.3%.

Other Findings

  • Heavier women lost less weight during treatment and regained less in the first year of follow-up
  • Weight-loss during treatment was not related to long-term outcome in women.
Author Conclusion:
  1. Long-term stability of weight losses produced by behavior therapy discouraging
  2. Less than 3% of subjects maintained post-treatment weights throughout the four years of follow-up, while nearly 40% gained weight at least to baseline levels or above at some point during follow-up. However, there were measurable residual benefits for behavioral weight management programs four and fiive years beyond termination of initial treatment.
  3. Evaluating our results is complicated by the lack of a standard comparison group
  4. Men and women quite similar at baseline, with respect to percentage overweight, age and age of onset and did not differ significantly in reported use of dietary or behavioral methods. However, there were clear differences in outcome.
    • Women lost less weight in treatment, but showed a consistently superior pattern of weight maintenance and greater resistance to returning to baseline weight
    • Women's prior program participation was associated with relatively good weight maintenance experience, whereas in men the opposite was true
    • Men with early and late age of onset of obesity showed identical weight loss and regain patterns. Women with onset before age 20 lost more weight and maintained the loss better than women with later age of onset.
    • Conclusion: Generalizations about weight loss and maintenance experience derived from one gender cannot be easily translated to the other and further thoughts might even be given to using different treatment approaches.
  5. There may be a powerful biological cause for weight regain phenomenon, but under appropriate circumstances this imperative might be overridden (i.e., social learning)
  6. Perhaps what is needed for long-term obesity management is longer or ongoing interventions.
Funding Source:
Government: NIH
Reviewer Comments:
  1. Very detailed review of existing data from two studies
  2. Findings related to long-term weight loss secondary to behavioral interventions discouraging.
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) N/A
  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) N/A
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? 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
  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
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
  1. Was the research question clearly stated? Yes
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.1. 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
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
  1.3. Were the target population and setting specified? Yes
  2. Was the selection of study subjects/patients free from bias? 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
  2.1. 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
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? 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
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
  3. Were study groups comparable? 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) N/A
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? 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.) N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  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? 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? Yes
  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
  3.5. 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
  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. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? 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
  4.2. 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
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? 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
  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? N/A
5. Was blinding used to prevent introduction of bias? N/A
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  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.) N/A
  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.) N/A
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  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
  5.4. 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
  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. 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? N/A
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? 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
  6.3. 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
  6.4. 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
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments 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? Yes
  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
  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. 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
  7.1. 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
  7.2. 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
  7.3. 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
  7.4. 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
  7.5. 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
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? 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. 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
  8.1. 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
  8.2. 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
  8.3. 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)? N/A
  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)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? 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
  8.6. 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
  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? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? N/A
  9.1. Is there a discussion of findings? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? 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. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes
  10.2. Was the study free from apparent conflict of interest? Yes