Development and Validation of an Instrument to Assess the Cognitive, Behavioral, and Environmental Factors Related to...

High sodium intake is a major risk factor for noncommunicable diseases, with most Canadians exceeding recommended levels. Population-wide sodium-reduction interventions include monitoring sodium knowledge, attitudes, and behaviors as a core activity. However, there is a lack of developed instruments incorporating qualitative research and behavioral theories, accompanied by robust validation methods and psychometric testing.

This study aimed to develop and validate a comprehensive instrument, the Behavioral Assessment Instrument for dietary Sodium (BAIS), assessing cognitive, behavioral, and environmental influences on sodium intake among Canadian adults.

Item development was informed by a prior national sodium survey, a Canadian qualitative study, relevant literature, and behavioral theories. Content validity was assessed by 11 experts over 2 rounds and evaluated by computing the content validity index (CVI) for individual items and scale average (S-CVI/Ave). Face validity was verified through one-on-one interviews with 10 Canadian adults (>18 y). Item response theory (IRT) assessed knowledge items, whereas exploratory factor analyses (EFA) and confirmatory factor analyses (CFA) validated the remaining constructs (n = 3236; 51.2% women; mean age 49.5 ± 17.7 y). Reliability analyses included intraclass correlation coefficients (ICC) for ordinal questions, Gwet's first-order agreement coefficient (AC1) for binary questions, and Cronbach's alpha.

Expert review led to iterative revisions, with round 2 achieving S-CVI/Ave = 1, indicating high content validity. Cognitive interviews (50% male, 23-62 y) confirmed item clarity. IRT results showed acceptable difficulty and discrimination of knowledge variables. EFA and CFA supported a 6-factor structure: Nutrition labeling behaviors, Hedonic influences, perceived control and self-efficacy, priority and concern, delayed concern, and sodium-reduction practices. Internal consistency ranged from acceptable to excellent. ICC was moderate for most ordinal variables, and AC1 was moderate to very good.

The BAIS represents the first validated Canadian instrument to assess multidimensional, theory-based drivers of sodium intake, supporting improved surveillance, policy development, and targeted interventions.