Definiendo la eficacia de la norma

In 2003 a Cochrane systematic review (search up to July 2001) reported a lack of research on the treatment of childhood obesity, only finding 18 randomised controlled trials, many of which had small sample sizes or other methodological limitations (Summerbell et al 2003). The authors were unable to draw definitive conclusions from this review. A further systematic review examined the nature and effectiveness of family involvement (McLean 2003). Although few studies existed, they indicated that parental involvement is associated with weight loss in children but not in adolescents, and that a greater range of behaviour change techniques improves outcome. The lack of UK based programmes in these reviews stimulated the development and piloting of the ‘Families for Health’ programme reported in this thesis.

Subsequently, the National Institute for Health and Clinical Excellence published a guidance document based on the evidence available for the treatment and prevention of obesity in children and adults up to December 2006 (NICE 2006a). The evidence for the NICE guidance was partially based on the

Cochrane review (Summerbell et al 2003), but also included evidence from controlled clinical trials and controlled before-and-after studies, as well as evidence published since the Cochrane review.

The results of the review were split into the treatment of obesity in clinical settings and non-clinical settings. 42 studies were in clinical settings, with 25 studies from USA, none from the UK, and almost all from university obesity research clinics. The highest level of evidence (1++) is available for the following interventions in specialist weight management programmes:-

 Physical activity and diet combined are more effective in weight management in children aged 4-16 years, than diet alone

 Behavioural treatment combined with physical activity and/or diet is effective in children/adolescents aged 3-18 years

 Behavioural treatment can be more effective if parents, rather than children (aged 6-16 years), are given the main responsibility for behaviour change.

The evidence relating to the treatment of childhood obesity in non-clinical or community-based interventions was poor, with only seven RCTs and three controlled ‘before and after’ studies found, and no studies from the UK. The review found insufficient evidence to compare the effectiveness of interventions with or without family involvement in non-clinical settings. This research is reflected in the guidelines from NICE for interventions to include a focus on lifestyle change within the family, with parents taking the main responsibility for

In recognition that many studies informing the evidence base were of poor quality (e.g. short follow-up) with little evidence from the UK, NICE (2006a) identified the following research questions for primary research in the UK:-

1. ‘What are the most effective interventions to prevent or manage obesity in children and adults in the UK?’

2. ‘How does the effectiveness of interventions to prevent or manage obesity vary by population group, setting and source of delivery ?

3. ‘What is the cost-effectiveness of interventions to prevent or manage obesity in children and adults in the UK?’

4. ‘What elements make an intervention effective and sustainable, and what training do staff need?

The Cochrane review published in 2003 (Summerbell et al 2003) has recently been updated, now including trials of interventions to treat obesity in children or adolescents published up until May 2008 (Oude Luttikhuis et al 2009). A new comprehensive search strategy found 46 additional randomised controlled trials which met the inclusion criteria, making a total of 64 RCTs (5230 participants) in the systematic review. Of the 64 trials, 10 (1424 participants) focused on anti- obesity drugs in adolescents (i.e. metformin, orlistat, sibutramine) and 54 (3806 participants) focused on lifestyle. Of the 54 RCTs focusing on lifestyle, 36 focused on behavioural oriented treatment programmes aiming to change diet, physical activity and sedentary behaviours (ranging from family-based therapy, cognitive-behavioural treatment, problem solving, multi-component behavioural therapy); 12 focused on physical activity / sedentary behaviour; and 6 focused on diet. For inclusion, the studies had to include a baseline and post-

intervention measurement of height and weight, with the primary outcome measure being the BMI z-score or percentage overweight. A range of secondary outcomes were also considered, including a focus on adverse outcomes. The quality of the RCTs was variable, although studies were not excluded from the narrative synthesis on this basis. Only two of the RCTs were from the United Kingdom (Hughes et al 2008, Daley et al 2006). The authors divided the 54 lifestyle studies for the purpose of analysis by the age of the child: 37 studies (4 dietary, 9 physical activity, 24 behavioural interventions) comprised children with a mean age <12 years and 17 studies (2 dietary, 3 physical activity, 12 behavioural interventions) comprised children with a mean age >12 years (i.e. adolescents).

A narrative synthesis and a meta-analysis are presented to establish the effect of behavioural family programmes on the change in BMI z-score, comparing them with standard or minimal care. Only four of the 24 behavioural interventions in children under 12 years fulfilled the criteria to be pooled, with 16 studies excluded from the meta-analysis because they had not been analysed using intention-to-treat principles. The Forest plot combining the remaining four studies showed that the mean difference between the groups in BMI z-score favoured the behavioural intervention over standard care at the 6-month follow- up (-0.06, 95% CI -0.12 to -0.01) (Figure 2.11a), but there was no benefit at 12- months (-0.04, 95% CI -0.12 to 0.04) (Figure 2.11b). The large variation in studies in terms of length of follow-up, different outcome measurements and methodological quality made it difficult to synthesise the results, questioning the

Figure 2.11 Forest Plots from the Cochrane Systematic Review on the Treatment of Obesity in children under 12 (Oude Luttikhuis et al 2009)

(a) Behavioural interventions in children < 12 years – 6-month follow-up

Similarly, the meta-analysis of behavioural interventions targeting children aged 12 years and older included results from only three of 12 interventions. The pooled effect for BMI z-score was in favour of the intervention compared with standard care or self-help at 6-months (-0.14, 95% CI: -0.17 to -0.12), and persisted until the 12-month follow-up. In adolescents the anti-obesity drugs orlistat and sibutramine, led to significant improvements when combined with lifestyle change (Oude Luttikhuis et al 2009).

The focus on potential adverse effects is an important addition in this systematic review. All 10 studies of anti-obesity drugs reported adverse events very comprehensively, although only 18 of 54 lifestyle studies reported measures of harm. No adverse effects on psychological well being, linear growth or eating disorders were found with lifestyle interventions.

The overall conclusion of the 2009 Cochrane review was that it is difficult to recommend one intervention over another. However, several studies indicate that family-based lifestyle interventions which combine dietary, physical activity and behavioural components can produce ‘a significant and clinically meaningful reduction in overweight in children and adolescents’(p2) compared with standard care, self-help or control (Oude Luttikhuis et al 2009). Combined interventions were more effective than interventions targeting diet or physical activity alone. Furthermore, parental involvement was identified as being particularly useful in children under 12 years.

2.8.2 Key Primary Studies Contributing to the Evidence Base for Family-