School Obesity Prevention Policies and Practices in Minnesota and Student Outcomes: A Longitudinal Cohort Study.

INTRODUCTION
The School Obesity-related Policy Evaluation (ScOPE) Study uses existing public surveillance data and applies a rigorous study design to evaluate effectiveness of school policies and practices impacting student behavioral and weight outcomes.

METHODS
The ScOPE Study used a cohort of 50 combined junior-senior and high schools in Minnesota to evaluate the change in weight-related policy environments in 2006 and 2012 and test the effect of policy change on students attending those schools in 2007 and 2013. Exposure variables included school practices about foods and beverages available in school vending machines and school stores, physical education requirements, and intramural opportunities. Primary study outcomes were average school-level ninth grade student BMI percentile, obesity prevalence, daily servings of fruits/vegetables, and daily glasses of soda.

RESULTS
Availability of fruits/vegetables in schools was associated with a significant increase in total daily intake among ninth grade students by 0.4 servings. Availability of soda in schools was associated with a significant increase in total daily intake among ninth grade boys by 0.5 servings. Less-healthy snack and drink availability in schools was associated with a small, significant increase (1%) in student BMI percentile at the school level.

CONCLUSIONS
Use of a school-level longitudinal cohort study design over a 6-year period uniquely adds to the methodologic rigor of school policy and practice evaluation studies. The ScOPE Study provides marginal evidence that school policies and practices, especially those that restrict vending and school store offerings, may have small effects on weight status among ninth grade students.