External validity reporting in behavioral treatment of childhood obesity: a systematic review

Context: To aid translation of childhood obesity interventions evidence into practice, research studies must report results in a way that better supports pragmatic decision making. The current review evaluated the extent to which information on key external validity dimensions, participants, settings, interventions, outcomes, and maintenance of effects, was included in research studies on behavioral treatments for childhood obesity.

Evidence acquisition: Peer-reviewed studies of behavioral childhood obesity treatments published between 1980 and 2008 were identified from (1) electronic searches of social science and medical databases; (2) research reviews of childhood obesity interventions; and (3) reference lists cited in these reviews. Included studies reported on a controlled obesity intervention trial, targeted overweight or obese children aged 2-18 years, included a primary or secondary anthropometric outcome, and targeted change in dietary intake or physical activity behaviors.

Evidence synthesis: 1071 publications were identified and 77 met selection criteria. Studies were coded on established review criteria for external validity elements. All studies lacked full reporting of generalizability elements. Across criteria, the average reporting was 23.9% (range=0%-100%). Infrequently reported were setting-level selection criteria and representativeness, characteristics regarding intervention staff, implementation of the intervention content, costs, and program sustainability.

Conclusions: Enhanced reporting of relevant and pragmatic information in behavioral investigations of childhood obesity interventions is needed to improve the ability to evaluate the applicability of results to practice implementation. Such evidence would improve translation of research to practice, provide additional explanation for variability in intervention outcomes, and provide insights into successful adaptations of interventions to local conditions.