Objective: We developed and evaluated the psychometric properties of the Diabetes Therapy-Related QOL (DTR-QOL) as a disease-specific, self-administered questionnaire to assess the influence of diabetes treatment on patient QOL, regardless of treatment method.
Methods: This new questionnaire was developed and validated in a standardized manner: Item development, pilot-testing and psychometric validation. A survey was conducted using the provisional version of the questionnaire, and reliability and validity were evaluated with psychometric testing.
Results: The provisional version of the questionnaire was generated with 29 items through literature review and pilot testing. For psychometric assessment, analyses were performed on the responses of 284 adult Japanese patients with diabetes. Factor analysis by the principal factor method with promax rotation revealed 4 factors; "burden on social activities and daily activities" (13 items), "anxiety and dissatisfaction with treatment" (8 items), "hypoglycemia" (4 items), and "satisfaction with treatment" (4 items). For reliability, the intraclass correlation was 0.92, and Cronbach's alpha coefficient was 0.94, indicating adequate test-retest reliability and internal consistency. For known-group validity, there were significant differences in scores for following variables: age, diabetes type, HbA1c, treatment method, glycemic control, hypoglycemia, nocturnal hypoglycemia, concern about weight gain, health status (patient assessment), and degree of communication with physician.
Conclusions: The DTR-QOL, with good reliability and validity, can assess the influence of diabetes treatment on patient QOL. The DTR-QOL can be used regardless of treatment method that patients receive, and this characteristic enables to detect a difference on patients QOL between treatment methods before and after a switch of treatment. Limitations of this study include representativeness of the patient sample. The relatively small number of patients with type 1 diabetes should be noted. Also, responsiveness of the DTR-QOL has not yet been examined.