Comparison of utilization, cost, adherence, and hypoglycemia in patients with type 2 diabetes initiating rapid-acting insulin analog with prefilled pen versus vial/syringe.

BACKGROUND

Studies examining outcomes of different insulin delivery systems are limited. The objective of this study was to compare healthcare utilization, costs, adherence, and hypoglycemia rates in patients with type 2 diabetes mellitus (T2DM) initiating rapid-acting insulin analog (RAIA) using prefilled pen versus vial/syringe.

METHODS

A retrospective analysis was conducted using a US claims database (1/1/2007 to 12/31/2008). Inclusion criteria were: ≥18 years old, with T2DM, ≥12 months of continuous eligibility, and new to RAIA. Difference-in-difference analyses after propensity score matching were conducted to compare changes in outcomes from 6 months prior to and 6 months after initiating RAIA with a prefilled pen versus vial/syringe (Wilcoxon rank-sum test for costs and t-test for other outcomes). Categories of utilization and costs (2009 USD) included total and diabetes-related inpatient, outpatient, and emergency room. Adherence was measured by proportion of days covered (PDC). Hypoglycemia was identified using ICD-9-CM codes.

RESULTS

Baseline characteristics were similar between the prefilled pen (n = 239) and vial/syringe (n = 590) cohorts after matching. Adherence to RAIA was greater in the prefilled pen cohort than the vial/syringe cohort (PDC: 54.6 vs. 45.2%, p < 0.001). While the increase in diabetes-related pharmacy costs from before to after initiating RAIA was greater in the prefilled pen cohort than the vial/syringe cohort (+$900 vs. +$607, p < 0.001), the prefilled pen cohort was associated with greater reductions in the total diabetes-related costs (-$235 vs. +$61, p = 0.006) and the utilization of oral anti-hyperglycemic agents (-1.3 vs. -0.7, p = 0.016). There were no significant differences in other outcomes.

LIMITATIONS

Claims databases do not provide optimal measures for adherence or T2DM severity, and only capture hypoglycemia events requiring clinical intervention.

CONCLUSION

Initiating RAIA with a prefilled pen was associated with better adherence and greater reduction in total diabetes-related costs than a vial/syringe. There was no significant difference in total healthcare costs.