Economic analysis of physical activity interventions.

BACKGROUND Numerous interventions have been shown to increase physical activity but have not been ranked by effectiveness or cost. PURPOSE This study provides a systematic review of physical activity interventions and calculates their cost-effectiveness ratios. METHODS A systematic literature review was conducted (5579 articles) and 91 effective interventions promoting physical activity were identified, with enough information to translate effects into MET-hours gained. Cost-effectiveness ratios were then calculated as cost per MET-hour gained per day per individual reached. Physical activity benefits were compared to U.S. guideline-recommended levels (1.5 MET-hours per day for adults and 3.0 MET-hours per day for children, equivalent to walking 30 and 60 minutes, respectively). RESULTS The most cost-effective strategies were for point-of-decision prompts (e.g., signs to prompt stair use), with a median cost of $0.07/MET-hour/day/person; these strategies had tiny effects, adding only 0.2% of minimum recommended physical activity levels. School-based physical activity interventions targeting children and adolescents ranked well with a median of $0.42/MET-hour/day/person, generating an average of 16% of recommended physical activity. Although there were few interventions in the categories of "creation or enhanced access to places for physical activity" and "community campaigns," several were cost effective. The least cost-effective categories were the high-intensity "individually adapted behavior change" and "social support" programs, with median cost-effectiveness ratios of $0.84 and $1.16 per MET-hour/day/person. However, they also had the largest effect sizes, adding 35%-43% of recommended physical activity, respectively. Study quality was variable, with many relying on self-reported outcomes. CONCLUSIONS The cost effectiveness, effect size, and study quality should all be considered when choosing physical activity interventions.