Development and psychometric testing of a theory-based tool to measure self-care in diabetes patients: the self-care of diabetes inventory

Background:Self-care is essential for patients with diabetes mellitus. Both clinicians and researchers must be ableto assess the quality of that self-care. Available tools have various limitations and none are theoretically based. Theaims of this study were to develop and to test the psychometric properties of a new instrument based on themiddle range-theory of self-care of chronic illness: the Self-Care of Diabetes Inventory (SCODI).Methods:Forty SCODI items (5 point Likert type scale) were developed based on clinical recommendations andgrouped into 4 dimensions: self-care maintenance, self-care monitoring, self-care management and self-careconfidence based on the theory. Content validity was assessed by a multidisciplinary panel of experts. A multi-centre cross-sectional study was conducted in a consecutive sample of 200 type 1 and type 2 diabetes patients.Dimensionality was evaluated by exploratory factor analyses. Multidimensional model based reliability wasestimated for each scale. Multiple regression models estimating associations between SCODI scores and glycatedhaemoglobin (HbA1c), body mass index, and diabetes complications, were used for construct validity.Results:Content validity ratio was 100%. A multidimensional structure emerged for the 4 scales. Multidimensionalmodel-based reliabilities were between 0.81 (maintenance) and 0.89 (confidence). Significant associations were foundbetween self-care maintenance and HbA1c (p= 0.02) and between self-care monitoring and diabetes complications(p= 0.04). Self-care management was associated with BMI (p= 0.004) and diabetes complications (p=0.03).Self-careconfidence was a significant predictor of self-care maintenance, monitoring and management (allp < 0.0001).Conclusion:The SCODI is a valid and reliable theoretically-grounded tool to measure self-care in type 1 andtype 2 DM patients.