CRD summary

This review concluded that the majority of school-based obesity programmes are effective, especially those targeting physical education and those aimed at reducing television viewing. However, poor reporting of the review methods and the absence of a formal assessment of study validity make the reliability of the authors’ conclusions unclear.

Authors' objectives

To evaluate the effectiveness and potential adverse effects of school-based obesity prevention programmes. A further aim was to identify the mechanisms for successful interventions with a view to their large-scale implementation.

Searching

MEDLINE was searched to August 2005 to identify relevant studies; the search terms were reported. In addition, the references of published reviews were screened, internet web searches were conducted, and letters were sent to researchers in order to identify additional studies.

Study selection

Assessment of study quality

The authors did not state that they assessed validity in terms of methodological quality. However, they addressed aspects of relevance to reviews of public health by assessing intervention quality and aspects of implementation (see How Were the Data Extracted From Primary Studies). The authors did not state how this assessment was performed.

Data extraction

The authors did not state how the data were extracted for the review, or how many reviewers performed the data extraction. In addition to reporting intervention effectiveness based on BMI and skin-fold measurements, data were extracted to answer questions borne out of published criteria to evaluate intervention comprehensiveness. For example, data were collected on the exposures addressed, the intervention setting, the potential influence of macro and micro level factors, sustainability, participation levels, tailoring and intervention reach. Data were also extracted on the theoretical framework used and the potential for intervention implementation within the context of existing initiatives.

Methods of synthesis

Results of the review

Twenty-five studies (evaluating 53,118 participants) were included in the review. All of the studies were controlled trials, with 18 incorporating some form of randomisation.

ssues relating to the quality of the intervention and implementation, including the exploration of differences and success mechanisms between effective and ineffective interventions, were reported in the paper. It was unclear what intervention components would succeed on a larger scale.

Seventeen studies (evaluating 42,301 participants) were deemed effective in terms of statistically significant differences between the intervention and comparison groups in measures of BMI, skin-folds, or both. Many of these included a physical activity component as part of the regular school curriculum, with others targeting reductions in television viewing. Four studies were effective for both outcome measures, with two studies deemed effective only for girls, and two studies equally effective for boys and girls. Another study was effective for girls but for BMI only. Three of the eight studies deemed ineffective reported small relative reductions in BMI or triceps skin-fold measures compared with controls. A further study was effective after 1 year, but this was not sustained at a 3-year follow-up.

Adverse outcomes were reported as those relating to unhealthy consequences of the intervention. One study showed a significant increase in underweight prevalence combined with a significant reduction in overweight and obesity prevalence. Three studies suggested a statistically significant increase in overweight prevalence as a result of the intervention.

Authors' conclusions

The majority of overweight and obesity prevention programmes were effective, in particular those targeting physical education in schools and reducing television viewing.

CRD commentary

This review answered a wide-reaching question using broad inclusion criteria for all aspects except the outcomes. The reliance upon one electronic database and some supplementary searching, together with the apparent absence of searching for unpublished material, means that relevant studies might have been missed. The review process was poorly reported, making it difficult to assess the potential for reviewer error and bias. The assessment of issues relating to intervention comprehensiveness and implementation was appropriate to this topic area. However, a methodological assessment of the included trials was not conducted; this makes it difficult to assess the reliability of the included studies. Heterogeneity amongst the included studies prompted an appropriate narrative summary of effective and non-effective interventions, although the absence of statistical data means that it is not possible to verify the authors’ summary results. Given these limitations, the reliability of the authors’ conclusions is unclear.

Implications of the review for practice and research

Practice: The authors stated that better tailoring of interventions may be needed to take account of differences in gender, age and ethnicity. Further efforts should be made to improve participation rates and sustainability, and interventions should address the physical and social environment in which they operate.

Research: The authors stated that future studies should address the prevention of adverse outcomes by reporting intervention impact on the frequency distribution of BMI and adiposity measures. More comprehensive body composition measures should be used. The combination of primary and secondary prevention also requires further evaluation.

Funding

The review was commissioned by the Weight Management in Public Health Task Force of the European Branch of the International Life Sciences Institute.

Bibliographic details

Doak C M, Visscher T L, Renders C M, Seidell J C. The prevention of overweight and obesity in children and adolescents: a review of interventions and programmes. Obesity Reviews 2006; 7(1): 111-136. [PubMed: 16436107]

Other publications of related interest

Summerbell CD, Chinnock P, O’Malley C, van Binsbergen JJ. The Cochrane Library: more systematic reviews on nutrition needed. Eur J Clin Nutr 2005;59:S172-8; discussion S195-6.

Indexing Status

Subject indexing assigned by NLM

MeSH

Adolescent; Adult; Body Mass Index; Child; Female; Health Behavior; Humans; Male; Obesity /prevention & control; Overweight

AccessionNumber

12006001347

Database entry date

01/12/2008

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.