Developing content for a diabetes-specific quality of life item bank and computerized adaptive testing system (DiabCAT)

Objective To develop content for a type 2 diabetes-specific (T2DM) quality of life (QoL) computerized adaptive testing-CAT testing system ("DiabCAT"). Methods In this cross-sectional, qualitative study, domains and items for DiabCAT were generated in Phase 1 from: 1) a literature review of existing T2DM-related QoL patient-reported outcome measures (PROMs) (n = 34) and qualitative papers (n = 26); 2) semi-structured interviews and focus groups with patients with T2DM (September 2021-April 2022; N = 37); and 3) semi-structured interviews with DM healthcare practitioners (n = 8). In Phase 2, items were grouped based on similarities in meaning (binning), systematically refined to a core set (winnowing), and then iteratively pre-tested using cognitive interviews until no new issues emerged. Results Of the 37 Phase 1 participants, the mean (standard deviation, SD) age and T2DM duration was 60.6 (11.8) and 13.2 (7.4) years, respectively. Overall, 59.5% were male, with two participants (5.4%) managing their DM with diet and exercise alone, 25 (67.6%) on medication, and 10 (27.0%) on insulin. After Phase 1, nine QoL domains comprising 1134 items were identified, of which 360 were from qualitative interviews. Following binning and winnowing (Phase 2), two lots of two domains were merged, and items were reduced to 266. After cognitive interviews with 15 T2DM patients (mean (SD) age: 63.6 (11.6) years; 66.7% male), 12 items were deleted (e.g. item unclear), 2 added (e.g. content not captured) and 20 modified (e.g. complex phrasing simplified), leaving 256 items across seven QoL domains: Symptoms (n = 33), Activity Limitation (n = 23), Emotional well-being (n = 47), Concerns (n = 48), Diabetes Management (n = 63), Diet (n = 18) and Work (n = 24). Conclusion Our DiabCAT instrument captures numerous QoL challenges and is ready for further psychometric testing in patients with T2DM. Once operationalized on our cloud-based CAT platform, DiabCAT could offer clinicians and researchers a comprehensive tool to assess the QoL impact of T2DM and the effectiveness of associated management modalities. Impact statement This study describes the patient-centred content development stages for a novel quality of life PROM in type 2 diabetes. Future work will calibrate the items for administration via CAT, enabling QoL scores to be rapidly yet precisely measured in real-time research and clinical applications.