Development, validity, and reliability of the Street Food and Beverage Tool: (SFBT)

Abstract

Objective:

To develop and evaluate the validity and reliability of the Street Food and Beverage Tool (SFBT).

Design:

This methodological study contains two phases: a) tool development, which involves conducting a systematic review followed by expert evaluation of the items, the creation of a Nutritional Healthfulness Index (NH), and pilot testing; and b) evaluation of the Tool’s Validity and Reliability: Content validity was judged by an external technical group, which evaluated the adequacy and pertinence of each tool item. Construct validity was evaluated around schools by testing the hypothesis: In high-income areas, there will be greater availability of healthy food and beverages at street food outlets (SFOs), as measured by the NH-index. Inter-rater and test-retest reliability were assessed outside subway stations. Pearson’s correlation, Cohen’s kappa, and Content validity Indexes were used for reliability and validation. A multinomial regression model was used to estimate construct validity.

Setting:

Mexico City, Mexico.

Subjects:

80 SFOs at subway station exits and 1,066 around schools from diverse income areas.

Results:

The SFBT content validity index was satisfactory. The construct validity of the NH-index indicated higher values in higher-SDI areas. The NH-index showed a positive linear correlation between raters and across the first and second evaluations. The majority of item availability (>60%) showed moderate to strong kappa values for inter-rater and test-retest reliability.

Conclusions:

The SFBT is a reliable and valid tool for assessing the availability of foods and beverages. Compared to other tools, it can measure the nutritional quality of SFOs expressed as an NH-index.