Cafeteria assessment for elementary schools (CAFES): development, reliability testing, and predictive validity analysis

BACKGROUND: Strategies to reduce childhood obesity and improve nutrition include creating school food environments that promote healthy eating. Despite well-documented health benefits of fruit and vegetable (FV) consumption, many U.S. school-aged children, especially low-income youth, fail to meet national dietary guidelines for FV intake. The Cafeteria Assessment for Elementary Schools (CAFES) was developed to quantify physical attributes of elementary school cafeteria environments associated with students’ selection and consumption of FV. CAFES procedures require observation of the cafeteria environment where preparation, serving, and eating occur; staff interviews; photography; and scoring. METHODS: CAFES development included three phases. First, assessment items were identified via a literature review, expert panel review, and pilot testing. Second, reliability testing included calculating inter-item correlations, internal consistency (Kuder-Richardson-21 coefficients), and inter-rater reliability (percent agreement) based on data collected from 50 elementary schools in low-income communities and 3187 National School Lunch Program participants in four U.S. states. At least 43% of each participating school’s students qualified for free- or reduced-price meals. Third, FV servings and consumption data, obtained from lunch tray photography, and multi-level modeling were used to assess the predictive validity of CAFES. RESULTS: CAFES’ 198 items (grouped into 108 questions) capture four environmental scales: room (50 points), table/display (133 points), plate (4 points), and food (11 points). Internal consistency (KR-21) was 0.88 (overall), 0.80 (room), 0.72 (table), 0.83 (plate), and 0.58 (food). Room subscales include ambient environment, appearance, windows, layout/visibility, healthy signage, and kitchen/serving area. Table subscales include furniture, availability, display layout/presentation, serving method, and variety. Inter-rater reliability (percent agreement) of the final CAFES tool was 90%. Predictive validity analyses indicated that the total CAFES and four measurement scale scores were significantly associated with percentage consumed of FV served (p < .05). CONCLUSIONS: CAFES offers a practical and low-cost measurement tool for school staff, design and public health practitioners, and researchers to identify critical areas for intervention; suggest low- and no-cost intervention strategies; and contribute to guidelines for cafeteria design, food presentation and layout, and operations aimed at promoting healthy eating among elementary school students. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12889-018-6032-2) contains supplementary material, which is available to authorized users.