Psychometric properties of the revised Diabetes Knowledge Test using Rasch analysis

초록

Objective: The revised Diabetes Knowledge Test (DKT2) is the instrument that is the most widely used for measuring diabetes knowledge; nevertheless, its structural validity has never been evaluated. This study aimed to determine the psychometric properties of the DKT2.Methods: This study performed a secondary data analysis of people with diabetes recruited at university hospitals. Rasch analysis was used.Results: One item in the 14-item DKT2 measuring general diabetes knowledge exhibited a poor-fit, and so it was eliminated. The person-item map showed that items of greater difficulty need to be added to the instrument. The principal-components analysis of residuals revealed a unidimensional structure. The person reliability was 0.50, with a person separation index of 1.01. Measurement invariance was not satisfied for items 11 and 2 according to gender and age.Conclusions: The unidimensional structure of the 13-item DKT2 demonstrated poor person reliability and a low person separation index. Females and elderly persons found it more difficult to respond to items 11 and 2, respectively. Practice implications: Careful consideration is necessary when using the 13-item DKT2 in practice and research. It is recommended for future studies to add items of greater difficulty to the instrument.(c) 2021 Elsevier B.V. All rights reserved.

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