This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn.

The use of mixed treatment for childhood obesity, incorporating both group and individual approaches to treatment. The comparator was group treatment only.

Treatment.

Cost-effectiveness analysis.

The study population comprised families with obese children aged from 8 to 12 years. The families had to meet the following inclusion criteria:

the child was between 20 and 100% overweight;

neither parent was greater than 100% overweight;

one parent was willing to attend treatment meetings;

no family member was participating in an alternative weight control programme,

no child or parent had current psychiatric problems; and

there were no dietary or exercise restrictions on the child or parent.

The setting was community. The economic analysis was carried out in the USA.

The dates during which the effectiveness, resource use and cost data were obtained were not reported. The price year was not reported.

The effectiveness data were derived from a single study.

The costing was carried out prospectively on the same patient sample as that used in the effectiveness analysis.

Thirty-one families were enrolled in the study. The families were recruited through newspaper advertisements and by physician referrals. No power calculations were performed to determine the sample size.

This was a randomised controlled study carried out in the community. The method of randomisation ws not stated. The families were seen at 6 and 12 months after the treatment was started. Two families dropped out before treatment began and five families refused to participate in the follow-up assessments. There were 24 families for which complete data were available.

The clinical study was analysed on an intention to treat basis. The primary health outcomes used were the reduction in standardised body mass index (Z-BMI) and the percentage overweight. The groups were comparable in terms of the demographic and anthropometric characteristics of the children and parents, with the exception of the parents' height.

There was a significant change over time in terms of how overweight the participant was (percentage overweight), (p<0.001), and the Z-BMI, (p<0.001).

For children (n=24), the percentage overweight changed by -9.97 from baseline to 6 months, and by -8.04 from baseline to 12 months. The Z-BMI changed by -0.59 from baseline to 6 months, and by -0.64 from baseline to 12 months.

For parents (n=24), the percentage overweight changed by -6.67 from baseline to 6 months, and by -5.31 from baseline to 12 months. The Z-BMI changed by -0.31 from baseline to 6 months, and by -0.29 from baseline to 12 months.

For obese parents (n=18), the percentage overweight changed by -7.03 from baseline to 6 months, and by -5.70 from baseline to 12 months. The Z-BMI changed by -0.39 from baseline to 6 months, and by -0.31 from baseline to 12 months.

There were no main effects or interactions due to the type of group or generation.

The two groups were similar in terms of the Z-BMI and the percentage overweight for the children and their parents.

The benefit measures used in the economic analysis were the reductions in Z-BMI and percentage overweight.

The direct costs were not discounted due to the short timeframe of the study (less than one year). The quantities and costs were reported separately. The direct costs related to the orientation costs and the treatment costs. The orientation costs included advertising, materials and salary. The treatment costs included materials, travel and salary. The quantity/cost boundary adopted was that of the health service. The source of the cost data was not reported. The price year was not reported.

The costs were analysed using a one-way analysis of variance.

The indirect costs were not included.

US dollars ($).

No sensitivity analyses were reported.

See the 'Effectiveness Results' section.

The total costs amounted to $491.48 per family for the group only treatment, and $1,390.72 per family for the mixed treatment. The difference was statistically significant.

A cost-effectiveness ratio was calculated for each benefit measure by dividing the charges over 12 months by the total cost. At 12 months, a decrease of 0.005 percentage overweight units per dollar was observed for the mixed group, compared with a decrease of 0.014 percentage overweight units per dollar with the group treatment, (p<0.01). At 12 months, a decrease of 0.0004 Z-BMI units per dollar was observed for the mixed group, compared with a decrease of 0.001 Z-BMI units per dollar with the group treatment.

The authors argued that family-based behavioural treatment for childhood obesity was more cost-effective when provided in a group format, than when provided in a combined group and individual approach. The cost-effectiveness of the treatment extended to parents.

The choice of comparator was justified on the grounds that it involved less staff. You should decide if these health technologies are relevant to your setting.

The analysis was based on a randomised, controlled study, which was appropriate for the study question, and should have good validity although the rample size was small partly due to drop-outs and refusals (to paraticipate). The method of randomisation was not stated. The inclusion criteria were reported, as were the demographic characteristics of the children and parents. The treatment groups were comparable in terms of the demographic and anthropometric characteristics of the children and parents, with the exception of the parents' height. The study sample was representative of the study population. Appropriate statistical analyses were undertaken.

The benefits were estimated directly from the effectiveness analysis. Two measures of health benefit were therefore used in the economic analysis.

The positive features of the cost analysis were that all relevant direct cost categories were included, and that the quantities and costs were reported separately. This made it possible to replicate the cost results in other settings. Further, statistical analyses were performed on the cost estimates. However, the price year was not reported. The authors did not conduct sensitivity analyses on the quantities or costs, which may have limited the generalisability of the results. The authors included the costs of recruiting patients, but did not quantify the costs to the families who participated in the study.

The authors made appropriate comparisons of their findings with those from other studies, but did not address the issue of generalisability to other settings. The authors did not seem to present their results selectively. The study considered families with obese children aged from 8 to 12 years, and this was reflected in the authors' conclusions. Given that the effectiveness results were shown to be similar between groups, the authors could have carried out a cost-minimisation analysis. It should be noted that the study had a small sample size and no power calculations were reported.

The dates during which the effectiveness, resource use and cost data were not reported, and neither was the price year. Further research is needed to determine if the current results are generalisable to more obese children, since the population studied was mild to moderately obese. The authors stated that there may be some self-selection bias inherent in recruiting families for a study that provides family-based treatment. They also stated that the effects of the interventions may change over time, implying that analyses over a long timeframe would be useful.

The authors argued that family-based behavioural treatment for childhood obesity was more cost-effective when provided in a group format, than when provided in a combined group plus individual approach. In addition, the cost-effectiveness of the treatment extended to parents. Further research is needed to determine if the current results generalise to more obese children. Also, to determine the cost-effectiveness of treating only one member of the family, versus concurrent treatment of both parent and child.

Funded in part by a grant from the National Institutes of Diabetes and Digestive Diseases, National Institute of Health, grant number DK 53849.