Medication adherence and the associated health-economic impact among patients with type 2 diabetes mellitus converting to insulin pen therapy: an analysis of third-party managed care claims data.

OBJECTIVE This study evaluated the impact on adherence, hypoglycemic events, resource utilization, and the associated health care costs of converting from administration of insulin therapy by a vial/syringe to an insulin analogue pen device in patients with type 2 diabetes mellitus. METHODS This pre-post analysis used an integrated medical and pharmacy claims database containing information for >40 million covered lives from 57 managed care health plans in the United States. Adults with a diagnosis of type 2 diabetes whose treatment was converted from conventional human or analogue insulin injection (vial/syringe) to a prefilled insulin analogue pen from July 2001 through December 2002, with no use of an insulin analogue pen device in the preceding 6 months, were identified and analyzed retrospectively. The primary end points were adherence (as measured by a medication possession ratio [MPR] > or =80%); the odds ratio (OR) for hypoglycemic events requiring health care resource utilization and resulting in a claim; the association between adherence and hypoglycemic events; and all-cause, hypoglycemia-attributable (HA), and diabetes-attributable (DA) health care costs. RESULTS A total of 1156 subjects were identified and analyzed (mean [SD] age, 45.4 [13.7] years; 53.8% male; previous insulin vial use: 595 [51.5%] human, 561 [48.5%] analogue). Medication adherence was significantly improved after conversion to the insulin pen device (from 62% to 69%; P < 0.01). The proportion of subjects considered adherent was significantly higher in the period after the conversion compared with before the conversion (54.6% vs 36.1%, respectively; P < 0.01). The likelihood of experiencing a hypoglycemic event was significantly reduced after conversion (OR = 0.50; 95% CI, 0.37-0.68; P < 0.05), and the incidence of hypoglycemia in subjects with an MPR > or =80% decreased by nearly two thirds (incident rate ratio = 0.35; 95% CI, 0.11-0.81; P < 0.05). There were significant decreases in HA emergency department visits (OR = 0.44; 95% CI, 0.21-0.92; P < 0.05) and physician visits (OR = 0.39; 95% CI, 0.24-0.64; P < 0.05), whereas HA-related hospitalizations and outpatient visits remained similar after conversion. Total mean all-cause annual treatment costs were reduced by $1590 per patient (from $16,359 to $14,769; P < 0.01). Annual HA costs were reduced by $788 per patient (from $1415 to $627; P < 0.01), predominantly as a result of decreased hospitalization costs (from $857 to $288; P < 0.01). Annual DA costs were reduced by $600 per patient (from $8827 to $8227; P < 0.01). CONCLUSIONS Among these patients with type 2 diabetes treated in a managed care setting, a switch from administration of insulin therapy by vial/syringe to a prefilled insulin analogue pen device was associated with improved medication adherence, fewer claims for hypoglycemic events, reduced emergency department and physician visits, and lower annual treatment costs.