Adaptation and evaluation of the Nutrition Environment Measures Survey in Restaurants for the Spanish Mediterranean context (NEMS-R-MED)

Abstract

Background: The Nutrition Environment Measures Survey in Restaurants (NEMS-R) is a validated tool originally developed in the United States for evaluating food environments in restaurants. This survey assesses the availability of healthy and unhealthy foods, the factors that facilitate or act as a barrier to healthy eating, food prices, and how foods are labeled and promoted. However, no such instrument exists for use in Spain, where the Mediterranean dietary context and restaurant culture differ significantly. The objective of this study was to adapt the NEMS-R instrument to the Spanish Mediterranean context (NEMS-R-MED) and evaluate its reliability and construct validity.

Methods: Following a structured process of cultural adaptation-including translation, back-translation, expert review, and pilot testing-the NEMS-R-MED was applied independently by two raters in 57 restaurants across five neighborhoods in Alicante with varying socioeconomic statuses between November and December 2023. One of the raters evaluated the same restaurants again 30 days later. Inter-rater and intra-rater reliability were assessed using Cohen's kappa. Construct validity was tested using two techniques: (1) exploratory factor analysis and (2) known groups analysis, used to compare NEMS-R-MED scores between different types of restaurants and neighborhood socioeconomic levels.

Results: Almost perfect inter-rater and intra-rater agreements were observed for most items (k > 80). Factor analysis revealed different constructs for each of the studied questions, which aligned with the theoretical constructs of the questionnaire. Significant differences in NEMS-R-MED scores were observed between sit-down restaurants, bar-cafeterias, and fast-food establishments, as well as across neighborhoods of different socioeconomic statuses, particularly in the "barriers to healthy eating" subscale.

Conclusions: The adapted NEMS-R-MED instrument is a valid and reliable audit tool for assessing the food environment in restaurants within Spanish Mediterranean contexts. Additionally, NEMS-R-MED was able to discriminate effectively between restaurant types and neighborhoods with different socioeconomic statuses.

Keywords: NEMS-R-MED; food environment; measurement; restaurants; surveys and questionnaires; validation study.