Background: Although many different types of insulin delivery devices are currently available, there is no well-accepted, validated method to assess patient satisfaction with these devices and their impact on quality of life and other patient-reported outcomes. To address this problem, we developed the Insulin Device Satisfaction Survey (IDSS) and herein describe its construction and validation. We then examine how key patient factors are associated with device satisfaction.
Materials and methods: Items were developed from interviews with adults with type 1 diabetes (T1D) (n=10) and type 2 diabetes (T2D) using insulin (n=10), as well as eight healthcare professionals, leading to an initial pool of 32 items. Separate exploratory factor analyses (EFAs) were conducted with T1D subjects (n=279) and insulin-using T2D subjects (n=209). Construct validity was established with overall well-being (World Health Organization-5), diabetes distress (Diabetes Distress Scale), diabetes self-efficacy (Self-Efficacy for Diabetes Management Scale), and subscales from the Insulin Delivery System Rating Questionnaire. Regression analyses examined associations between total scale satisfaction and demographics, insulin adherence, clinical indicators, and device type (pump vs. nonpump users).
Results: The two EFAs resulted in a 14-item scale for T1D subjects and a 12-item scale for T2D subjects, with eight items common across both samples. The EFAs yielded three coherent, meaningful factors in each sample, accounting for 55.6% (T1D sample) and 64.1% (T2D sample) of the variance. Validity was established by significant correlations with all criterion variables. For both samples, higher IDSS scores were significantly associated with better glycemic control and greater insulin adherence and pump use. For T2D subjects only, IDDS scores were significantly linked to fewer long-term complications, fewer low blood glucose readings, and older age.
Conclusions: The IDSS is a reliable, valid measure of insulin device satisfaction in both its T1D form and T2 form. It provides a comprehensive profile of sources of device satisfaction for use in clinical care and research.