Projecting the impact of a nationwide school plain water access intervention on childhood obesity: a cost-benefit analysis.

OBJECTIVE: This study aimed to project the societal cost and benefit of an expansion of a water access intervention that promotes lunchtime plain water consumption by placing water dispensers in New York school cafeterias to all schools nationwide.

METHODS: A decision model was constructed to simulate two events under Markov chain processes - placing water dispensers at lunchtimes in school cafeterias nationwide vs. no action. The incremental cost pertained to water dispenser purchase and maintenance, whereas the incremental benefit was resulted from cases of childhood overweight/obesity prevented and corresponding lifetime direct (medical) and indirect costs saved.

RESULTS: Based on the decision model, the estimated incremental cost of the school-based water access intervention is $18 per student, and the corresponding incremental benefit is $192, resulting in a net benefit of $174 per student. Subgroup analysis estimates the net benefit per student to be $199 and $149 among boys and girls, respectively. Nationwide adoption of the intervention would prevent 0.57 million cases of childhood overweight, resulting in a lifetime cost saving totalling $13.1 billion. The estimated total cost saved per dollar spent was $14.5.

CONCLUSION: The New York school-based water access intervention, if adopted nationwide, may have a considerably favourable benefit-cost portfolio.