Development and Validation of the Diabetes Quality of Life Brief Clinical Inventory

Abstract

Objective. To design and test the reliability and validity of a brief, treatment-focused version of the Diabetes Quality of Life (DQOL) questionnaire for use with both type 1 and type 2 diabetes. Research design and methods. Questionnaire packets including the DQOL, measures of current diabetes self-care behaviors, and demographic and health characteristics were mailed to 1,080 adults with type 1 or type 2 diabetes. A total of 498 patients returned completed packets. A three-stage statistical process was used to understand the underlying structure of the DQOL and to identify items most predictive of self-care behaviors and satisfaction with diabetes control. Results. Principal components analysis, conducted on 26 items predictive of the main criteria, identified five key underlying factors. For each component, best subset regression analysis was conducted to identify nonredundant questions that best explained self-care behaviors and satisfaction with diabetes control. A combined set of 15 questions was reliable (alpha = 0.85) and valid, though several questions were more relevant to type 1 or type 2 diabetes. For patients with type 1 diabetes, the 15-item brief inventory was equally or more effective at predicting self-care behaviors (shortened scale R2 = 0.360; full scale R2 = 0.254) and satisfaction with diabetes control (shortened scale R2 = 0.562; full scale R2 = 0.580) than the original 60-item DQOL. For type 2 diabetic patients, only satisfaction with diabetes control was well-predicted, but the 15-item inventory accounted for as much variance as the original 60-item DQOL (shortened scale R2 = 0.513; full scale R2 = 0.492). Conclusions. The 15-item DQOL Brief Clinical Inventory provides a total health–related quality of life score that predicts self-reported diabetes care behaviors and satisfaction with diabetes control as effectively as the full version of the instrument. In addition, it provides a vehicle for quickly screening patients for readiness and specific treatment-related concerns. It takes about 10 minutes to administer and can be used to identify quality of life issues that might not arise during the typical patient-provider encounter.