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

Abstract

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.

Key words::

• Adherence
• Insulin
• Pen device
• Type 2 diabetes
• Vial

Transparency

Acknowledgments

The authors would like to thank Khaled Sarsour, PhD, an employee of Eli Lilly and Company, for his input on the development of the study hypothesis.

Notes

* Novolog, Novolog Mix70/30, Novolog Mix50/50, and FlexPen are registered trademarks of Novo Nordisk Pharmaceuticals Inc. (Princeton, NJ, USA)

^† Humalog and the KwikPen are registered trademarks of Eli Lilly and Company (Indianapolis, IN, USA)

^‡ MarketScan is a registered trademark of Thomson Reuters (Ann Arbor, MI, USA)

^§ Apidra is a registered trademark of Sanofi-Aventis US LLC (Bridgewater, NJ, USA)