Psychometric Properties of the MDADI\u2014A Preliminary Study of Whether Less is Truly More?

Abstract

The MD Anderson Dysphagia Inventory (MDADI) is a 20-item dysphagia-specific QOL questionnaire with four subscales: global, emotional, functional, and physical. It is widely used in clinical practice and in research; however, its psychometric properties have been under-researched. We aim to evaluate the organisation of the MDADI subscales and identify any redundant items. The MDADI is a routinely collected outcome measure at two centres in northeast England. Questionnaires completed at three months following treatment were extracted from these existing databases. Factor analysis was carried out with the aim of reducing redundancy among the set of questionnaire items. Cases with missing values were excluded. A total of 196 complete patient questionnaires were used in factor analysis. A one-factor model accounted for around 50% of the total variance in item responses. The top five endorsed items (abbreviated by the questionnaire item keywords: Excluded, Irritate, Esteem, Social, and Why) in this one factor appeared in three (emotional, functional, and physical) of the four supposed MDADI subscales, i.e. global, emotional, functional, and physical. Our results suggest an overlap of three MDADI subscales across the top five endorsed items. The content of the top five questions all appear related to the psychosocial aspects of swallowing. This implies some redundancy of the items in the original subscales of the questionnaire. Using the most endorsed items, it appears feasible to abbreviate the 20-item MDADI questionnaire to a 5-item “MiniDADI” questionnaire, which is likely to have greater utility in routine clinical practice outside of research settings.