Improved Health-Related Quality of Life in a Phase 3 Islet Transplantation Trial in Type 1 Diabetes Complicated by Severe Hypoglycemia

Abstract

Objective: Attaining glycemic targets without severe hypoglycemic events (SHEs) is a challenging treatment goal for patients with type 1 diabetes complicated by impaired awareness of hypoglycemia (IAH). The CIT Consortium Protocol 07 (CIT-07) trial showed islet transplantation to be an effective treatment for subjects with IAH and intractable SHEs. We evaluated health-related quality of life (HRQOL), functional health status, and health utility before and after pancreatic islet transplantation in CIT-07 trial participants.

Research design and methods: Four surveys, the Diabetes Distress Scale (DDS), the Hypoglycemic Fear Survey (HFS), the Short Form 36 Health Survey (SF-36), and the EuroQoL 5 Dimensions (EQ-5D), were administered repeatedly before and after islet transplantation. Summary statistics and longitudinal modeling were used to describe changes in survey scores from baseline and to characterize change in relation to a minimally important difference (MID) threshold of half an SD.

Results: Improvements in condition-specific HRQOL met the MID threshold. Reductions from baseline in the DDS total score and its four DDS subscales (all P ≤ 0.0013) and in the HFS total score and its two subscales (all P < 0.0001) were observed across all time points. Improvements were observed after both 1 and 2 years for the EQ-5D visual analog scale (both P < 0.0001).

Conclusions: In CIT-07, 87.5% of the subjects achieved the primary end point of freedom from SHE along with glycemic control (HbA_1c <7% [<53 mmol/mol]) at 1 year post-initial islet transplantation. The same subjects reported consistent, statistically significant, and clinically meaningful improvements in condition-specific HRQOL as well as self-assessments of overall health.

Trial registration: ClinicalTrials.gov NCT00434811.

Figure 1

Condition-specific HRQOL score distributions over time. A: DDS total score. The DDS total score ranges from 1 to 6 with lower scores indicating less diabetes-related distress. B: HFS total score. The HFS total score ranges from 0 to 4 with lower scores indicated less fear of hypoglycemia. The thick horizontal line inside each box represents the median value. The diamond represents the mean value. Asterisks represent statistically significant changes from baseline, where *** indicates P < 0.0001.