Validation of Measures of Satisfaction with and Impact of Continuous and Conventional Glucose Monitoring

Abstract

Background:

The evaluation of patient-reported outcomes (e.g. impact, satisfaction) is important in trials of continuous glucose monitoring (CGM). We evaluated psychometric properties of the CGM Satisfaction Scale (CGM-SAT) and the Glucose Monitoring Survey (GMS).

Methods:

CGM-SAT is a 44-item scale on which patients (n = 224) or parents (n = 102) rated their experience with CGM over the prior 6 months. GMS is a 22-item scale on which patients (n = 447) or parents (n = 221) rated the blood glucose monitoring system they were using (home glucose meter with or without CGM) at baseline and 6 months.

Results:

The alpha coefficient for the CGM-SAT was ≥0.94 for all respondents and for the GMS was ≥0.84 for all respondents at baseline and 6 months. Parent–youth agreement was 0.52 for the CGM-SAT at 6 months and 0.24 and 0.20 for the GMS at baseline and 6 months for the Standard Care Group, respectively. Test–retest reliability of the GMS at 6 months for controls was r = 0.76 for adult patients, 0.63 for pediatric patients, and 0.43 for parents. Factor analysis isolated measurement factors for the CGM-SAT labeled Benefits of CGM and Hassles of CGM, accounting for 33% and 9% of score variance, respectively. For the GMS, two factors emerged: Glucose Control and Social Complications, accounting for 28% and 9% of variance, respectively. Significant correlations of CGM-SAT with frequency of CGM use between 6 months and baseline and GMS with frequency of conventional daily self-monitoring of blood glucose at baseline support their convergent validity.

Conclusions:

The CGM-SAT and GMS are reliable and valid measures of patient-reported CGM outcomes.