Economic impact of treatment duration and persistence with basal insulin in previously insulin-naive users

Abstract

BACKGROUND: Although insulin is a well-established therapy that is associated with improved clinical outcomes, adherence and persistence with insulin regimens are poor in patients with type 2 diabetes mellitus (T2DM). Diabetes-related health care costs and the impact of insulin persistence patterns on these health care costs have been previously studied; however, these aspects of insulin therapy have limited data beyond the first year of use and have not been characterized among patients previously naive to basal insulin. OBJECTIVES: To (a) describe and compare medical- and pharmacy-related costs, health care resource utilization, and comorbidities and complications during the initial year and second (experienced) year of basal insulin therapy, and (b) describe and compare the impact of continuous versus interrupted basal insulin use during each year. METHODS: This was a retrospective observational database analysis using claims from multiple U.S. commercial health plans (Truven Health MarketScan) in previously insulin-naive patients with T2DM who were initiated on basal insulin. Data collected included all-cause and diabetesrelated medical and pharmacy costs, health care resource utilization (i.e., number and type of outpatient visits, hospitalization, emergency department [ED] visits), medication use, and preselected comorbidities and complications. This cost analysis described and compared health care costs and resource use between the initial and experienced years and further compared health care costs and resource use between continuers and interrupters within each of those years. RESULTS: A total of 23,645 patients were included in the analysis; 12,224 were classified as continuers and 11,421 were classified as interrupters. Among all patients, mean increases from the initial year to the experienced year were observed for all-cause medical costs ($12,690-$13,408; P = 0.048), all-cause pharmacy costs ($6,253-$6,559; P < 0.001), and allcause health care costs ($18,943-$19,967; P = 0.006), after adjusting for inflation. All-cause pharmacy costs were significantly higher for continuers versus interrupters, but total diabetes-related medical care costs, all-cause ED costs, and all-cause medical costs were significantly lower, resulting in similar all-cause health care costs between continuers and interrupters in both the initial and experienced years. Among all patients, diabetesrelated inpatient visits and outpatient primary care physician (PCP) visits, total medical inpatient visits, and total medical outpatient PCP visits were significantly higher in the initial year than in the experienced year; however, there were fewer diabetes-related ED visits in the initial year. CONCLUSIONS: Initiation of basal insulin appears to be associated with increased health care costs, and treatment persistence pattern (continuers vs. interrupters) is further correlated with health care expenditures. Although associated with decreased pharmacy costs, interruption of therapy increases medical costs, underscoring the importance of addressing persistence to therapy.