Aims: Disordered eating behaviour encompassing a range of both mild and more extreme dieting behaviour in people with diabetes is a clinical concern. The aim of this study was to develop a brief screening instrument to assess sub clinical disordered eating from an existing measure of psychosocial functioning in diabetes (the Diabetes Health Profile (DHP-18)).
Methods: A combination of exploratory factor, Rasch and other psychometric analyses were used to develop the measure and assess the external validity of the instrument. Firstly, factor analysis was used to assess the dimensionality of the items tapping disordered eating included in the DHP-18. Secondly, Rasch analysis was applied to assess item performance (in terms of item ordering, differential item functioning, response dependency and item fit) with the aim of selecting items for the screening instrument. This was done using a large sample of people with Type 2 diabetes split into subsamples. Finally, the discriminant validity and reliability of the final instrument was assessed using an external dataset of people with diabetes.
Results: The disordered eating items clustered as one dimension. Rasch analysis demonstrated evidence of item disordering for three items (between the response levels ‘sometimes’ and ‘often’), and one item did not fit the Rasch model. The misfitting item was removed from the measure resulting in a final instrument including four items, two of which were rescored resulting in a scale from 0 to 10 (rescored on a 0 – 100 scale). The final instrument demonstrated discriminant validity between body mass index categories (p<0.001) and frequency of hypoglycaemic attacks (p<0.05), and had a good level of reliability (cronbach’s alpha = 0.71). Floor and ceiling effects were also acceptable.
Discussion: We have developed a psychometrically valid brief screening instrument to identify disordered eating (EBSD). The measure is quick and easy to complete and can be used alone or as part of the DHP-18. Further work is required to assess the psychometric performance of the measure for both Type 1 and 2 diabetes in comparison to other indicators of disordered eating severity.
Mulhern B1, Meadows K2, Churchman D3
1University of Sheffield, Sheffield, United Kingdom, 2DHP Research & Consultancy Ltd, Banbury, United Kingdom, 3University of Oxford, Oxford, United Kingdom
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