Development and validation of the insulin treatment satisfaction questionnaire

Abstract

Background: Treatment of diabetes mellitus (DM) is complex, requiring multifaceted lifestyle change or regulation and, for many, self-regulation of insulin levels in the blood. Historically, daily insulin treatment has been viewed as burdensome to patients, prompting newer formulations and improved delivery methods.

Objective: This multicenter, clinical study was designed to develop a conceptually sound, clinically meaningful, and psychometrically valid measure of insulin treatment satisfaction, applicable to a wide range of insulin therapies.

Methods: A 3-phase iterative process was employed to develop and validate the Insulin Treatment Satisfaction Questionnaire (ITSQ): (1) conceptual development of items, (2) preliminary validation among patients with DM, and (3) confirmatory validation among patients with DM.

Results: The ITSQ was validated with 170 patients in phase 2 and 402 patients in phase 3. Confirmatory factor analysis produced a 5-factor, 22-item instrument assessing regimen inconvenience, lifestyle flexibility, glycemic control, hypoglycemic control, and satisfaction with the insulin delivery device. Results for reliability and construct validity of the final version were consistent in both samples of patients treated with insulin, with different data collection methods. Internal consistency (using Cronbach alpha coefficient) of the subscales ranged from 0.79 to 0.91. Test-retest reliability (using Spearman rank correlation coefficients) ranged from 0.63 to 0.94. ITSQ scores showed moderate to high correlation with related measures of treatment burden. The ITSQ differentiated among insulin delivery methods, glycosylated hemoglobin values, the number of times the patient required assistance administering insulin, and insulin adherence.

Conclusion: In our study samples, the ITSQ appeared to be conceptually and psychometrically sound and applicable to a wide range of insulin therapies.