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.