DM: Weight Management (2007)
Data Sources:
- electronic searches included Medline, EMBASE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Educational Resources Information Center (ERIC), PsychInfo, Web of Science, Biosis, Nutrition Abstracts and Review, Cochrane Library, and Cochrane Register of Controlled Trials.
- hand searched relevant journals including Diabetes Care, International Journal of Obesity and Related Metabolic Disorders, Obesity Research, American Journal of Clinical Nutrition and Journal of the American Dietetic Association
- Attempted to contact authors if data were unclear or missing.
Study Selection
- published and unpublished RCT in any language that examined weight loss or weight control trials involving dieting, physical activity or behavioral interventions
- subjects were adults > 18 years of age with type 2 diabetes, recorded body weight or BMI, and follow-up interval of >12 months.
- studies of < 12 months duration
Recruitment: not applicable
Design: Systematic review protocol using the Cochrane Collaboration Method
Blinding used: not applicable
Intervention: not applicable
Statistical Analysis:
- based on 22 eligible studies in 21 publications
- meta-analysis to combine continuous data when two or more studies reported an outcome of interest
- pooled effects determined using DerSimonian and Laird random-effects model; the three groups of studies were:
- any intervention versus usual care
- very low-calorie diet versus low-calorie diet
- physical activity versus no or less intensive physical activity
- meta-regression to determine if study-level characteristics affected between-group change in weight
- heterogeneity examined using chi-squared test
Timing of Measurements: Two reviewers independently abstracted relevant demographic and intervention characteristics. They reached consensus through discussion.
Dependent Variables
- weight loss
- percentage of baseline weight lost (based on individual data)
- body mass index
- fasting blood glucose
- glycated hemoglobin (HbA1c)
- blood pressure
- lipid concentrations
Independent Variables
- dietary (low calorie diets of 800 to 1500 kcal/day or very low calorie diets (<800 kcal/day).
- physical activity (involved specific approach to increasing activity levels such as counseling, exercise prescription or participation in supervised or unsupervised exercise program)
- behavior therapy (addressed barriers to diet or physical activity; used strategies such as social support or stimulus control)
Control Variables
Initial N: 22 studies with 4659 subjects (range 20 to 2205 participants per study)
Attrition (final N): 0 to 30%; completion rate was < 80% in five studies
Age: mean age 55 years
Ethnicity: not described
Other relevant demographics: mean duration of diabetes 6.5 years
Anthropometrics
Location: worldwide studies
| Comparison | Number of Studies | Number of Subjects | Weight Loss | 95% CI |
| Any intervention vs Usual Care |
7 |
585 |
1.7 kg |
|
|
Very low calorie diet vs low-calorie diet |
2 |
126 |
3.0 kg |
-0.5 to 6.4 kg |
|
Physical activity vs no or less intensive physical activity |
2 |
53 |
3.9 kg |
-1.9 to 9.7 kg |
Weight Change for Single Study Arms
Intervention
Number of Studies
Number of Subjects at Follow-up
Weight Change 95% CI (kg)
P Value for Heterogeneity
Usual care
7
564
-2.0 (-3.5 to -0.6)
0.05
12
917
-3.7 (-5.1 to -2.3)
<0.0001
Low-calorie diet
3
232
-1.8 (-3.2 to -0.3)
0.61
2
53
-4.0 (-7.2 to -0.7)
1.0
Low-calorie diet, physical activity, behavioral intervention
13
485
-4.1 (-5.4 to -2.9)
0.10
2
126
-7.7 (-9.8 to -5.5)
0.55
Other Findings
Changes in HbA1c generally corresponded to weight loss; between-group differences were not significant.
| Government: | CDC |
|
Quality Criteria Checklist: Review Articles
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| Relevance Questions | |||
| 1. | Will the answer if true, have a direct bearing on the health of patients? | Yes | |
| 2. | Is the outcome or topic something that patients/clients/population groups would care about? | Yes | |
| 3. | Is the problem addressed in the review one that is relevant to dietetics practice? | Yes | |
| 4. | Will the information, if true, require a change in practice? | N/A | |
| Validity Questions | |||
| 1. | Was the question for the review clearly focused and appropriate? | Yes | |
| 2. | Was the search strategy used to locate relevant studies comprehensive? Were the databases searched and the search termsused described? | Yes | |
| 3. | Were explicit methods used to select studies to include in the review? Were inclusion/exclusion criteria specified andappropriate? Wereselectionmethods unbiased? | Yes | |
| 4. | Was there an appraisal of the quality and validity of studies included in the review? Were appraisal methodsspecified,appropriate, andreproducible? | Yes | |
| 5. | Were specific treatments/interventions/exposures described? Were treatments similar enough to be combined? | Yes | |
| 6. | Was the outcome of interest clearly indicated? Were other potential harms and benefits considered? | Yes | |
| 7. | Were processes for data abstraction, synthesis, and analysis described? Were they applied consistently acrossstudies and groups? Was thereappropriate use of qualitative and/or quantitative synthesis? Was variation in findings among studies analyzed? Were heterogeneity issued considered? If data from studies were aggregated for meta-analysis, was the procedure described? | Yes | |
| 8. | Are the results clearly presented in narrative and/or quantitative terms? If summary statistics are used, are levels ofsignificance and/or confidence intervals included? | Yes | |
| 9. | Are conclusions supported by results with biases and limitations taken into consideration? Are limitations ofthe review identified anddiscussed? | Yes | |
| 10. | Was bias due to the review's funding or sponsorship unlikely? | Yes | |