Validation of measures of satisfaction with and impact of continuous and conventional glucose monitoring.
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 > or = 0.94 for all respondents and for the GMS was > or = 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.
D000293:Adolescent; D000328:Adult; D001786:Blood Glucose / Q000032:analysis*; D015190:Blood Glucose Self-Monitoring / Q000379:methods* / Q000523:psychology / Q000592:standards; D002648:Child; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000188:drug therapy* / Q000523:psychology; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D007328:Insulin / Q000008:administration & dosage*; D008137:Longitudinal Studies; D010290:Parents; D017060:Patient Satisfaction; D025341:Principal Component Analysis; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D055815:Young Adult
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin
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