Nonadherence to antidiabetic therapies represents a major challenge to clinicians treating patients with diabetes. Adherence rates range from 62% to 64% for patients with type 2 diabetes mellitus (T2DM) taking insulin therapy.1
Barriers to adherence include “complicated regimens, fear of injection pain, social embarrassment, lack of confidence about self-injection, perception of injectable therapy as inconvenient, and belief that insulin use is the last resort.”2
Additional barriers to adherence are patients’ fears about insulin-induced hypoglycemia3 and physicians’ delay of initiation of insulin therapy, due to concerns about nonadherence.4
Improving adherence to medication regimens is critical, as nonadherence leads to poorer glycemic control and increased risk of diabetic complications.2
Moreover, greater medication adherence has been found to be associated not only with improved glycemic control but also with decreased health care utilization.5 Therefore, it is important to examine the most effective means of increasing adherence in patients with T2DM.
Insulin pen devices incorporate the insulin and syringe in a single unit and have been found to address some of the barriers to adherence, as compared to conventional vials/syringes.2 Reasons that patients prefer pen devices include that they are easier to use, are more discrete, and elicit less fear in terms of self-injection.2 Additionally, pens may have greater dosing accuracy, compared with vials and syringes.2
Several observational studies have found greater adherence with insulin pens than with vials/syringes.6,7,8,9
Although insulin pens are associated with higher acquisition costs than conventional vials and syringes,2 pens have nevertheless been found to be associated with lower overall health care utilization costs.
Patients who switched from vials/syringes to pens have been found to have decreased risk of hypoglycemic events, decreased emergency department visits, and decreased physician visits.9,10
One retrospective study found that, although adherence rates were comparable, pen use was associated with lower all-cause costs than vials/syringes, in patients where treatment was initiated with pen therapy.11
To investigate both adherence and health care utilization costs, Asche and colleagues2 performed a longitudinal, retrospective analysis of two major outpatient health claims databases (MarketScan and IMS LifeLink) over a four-year period (January 1, 2004 through December 31, 2007), for patients with type 1 diabetes mellitus (T1DM) and T2DM who initiated insulin aspart with a pen versus vial/syringe.2
Hypoglycemic episodes were identified by any claim containing a diagnosis code for hypoglycemia. Patients were excluded if they had used insulin aspart pen or insulin aspart vial/syringe during the six months prior to index date.
A total of 10,253 patients from the MarketScan database (6,065 in the pen group and 5,523 in the vial/syringe group) and 7,619 from the LifeLink database (4,512 in the pen group and 3,782 in the vial/syringe group) were included in the analysis.
The researchers found that vial/syringe use was associated with 35% greater odds of at least one hypoglycemic episode than pen use in the MarketScan database (P<0.001) and 44% greater odds in the LifeLink database. (P<0.001) In the MarketScan database, the average cost for post-index hypoglycemic events in the vial/syringe cohort was 89% greater than in the pen cohort.
In the LifeLink database, the average cost in the vial/syringe cohort was 62.7% greater than in the pen cohort. (P<0.001) In the MarketScan database, diabetes-related costs in the vial/syringe cohort were 9.7% greater than in the pen cohort, and 7.2% greater in the LifeLink database (P<0.001 for both databases).