'Paper and pencil' vs. 'online' assessment: Exploring measurement invariance of the Yale Food Addiction Scale 2.0 in inpatients with severe obesity and the general population

During the last few years, food addiction (FA) increased its popularity both in clinical and research practice. To date, the gold standard for the assessment of FA is the Yale Food Addiction Scale 2.0 (YFAS2.0) - that conceptualizes FA as a substance-related and addictive disorder (SRAD), according to the DSM-5 diagnostic criteria. Despite an intensive worldwide use across heterogeneous populations, to date, no studies assessed the factorial validity and measurement invariance (MI) of the YFAS2.0 across samples that filled out the questionnaire with different assessment methods. The present study aimed to: extend evidence of YFAS2.0 factorial validity and explore its MI across four different groups. Participants (N = 470) completed the Italian YFAS2.0. Participants were grouped on the basis of their recruitment (inpatients with severe obesity vs. the general population) and the assessment methodologies ('paper and pencil' assessment vs. 'online' assessment). The CFA showed good fit indexes for the overall sample as well as for each of the different groups. Also, configural, metric, and strong invariance were achieved across the four groups. Findings suggested that the Italian YFAS2.0 can be considered a good psychometrically-based and structural invariant instrument for the assessment of FA in different samples and across different methods of assessment.