A disease-specific questionnaire for measuring patient-reported outcomes and experiences in the Swedish National Diabetes Register: Development and evaluation of content validity, face validity, and test-retest reliability.

Objective: To describe the development and evaluation of the content and face validity and test-retest reliability of a disease-specific questionnaire that measures patient-reported outcomes and experiences for the Swedish National Diabetes Register for adult patients who have type 1 or type 2 diabetes.

Methods: In this methodological study, a questionnaire was developed over four phases using an iterative process. Expert reviews and cognitive interviews were conducted to evaluate content and face validity, and a postal survey was administered to evaluate test-retest reliability.

Results: The expert reviews and cognitive interviews found the disease-specific questionnaire to be understandable, with relevant content and value for diabetes care. An item-level content validity index ranged from 0.6-1.0 and a scale content validity/average ranged from 0.7-1.0. The fourth version, with 33 items, two main parts and seven dimensions, was answered by 972 adults with type 1 and type 2 diabetes (response rate 61%). Weighted Kappa values ranged from 0.31-0.78 for type 1 diabetes and 0.27-0.74 for type 2 diabetes.

Conclusions: This study describes the initial development of a disease-specific questionnaire in conjunction with the NDR. Content and face validity were confirmed and test-retest reliability was satisfactory.

Practice Implications: With the development of this questionnaire, the NDR becomes a clinical tool that contributes to further understanding the perspectives of adult individuals with diabetes.