Persistence with Basal-Bolus Insulin Therapy in Patients with Type 2 Diabetes Mellitus and Effect on Clinical and Economic Outcomes: A Retrospective Claims Database Study.

Abstract

Persistence with multiple daily insulin injections (MDI) may be challenging for patients with type 2 diabetes (T2DM). However, limited information is available regarding the effect of persistence with MDI on outcomes. To evaluate persistence with basal and bolus insulin therapy and assess its relationship with clinical and economic outcomes in a real-world setting. This retrospective matched cohort study used 2012-2015 data from multiple U.S. commercial health plans (IBM MarketScan). Patients with T2DM aged 18-64 years with ≥ 2 basal and ≥ 2 bolus insulin claims during a 12-month period were eligible for inclusion if they had 18 months of continuous health plan enrollment (6-month baseline and 12-month post-index). Persistence during 12 months post-index was defined using 2 methods: (a) method 1, ≤ 90-day gaps in both basal and bolus insulin claims and (b) method 2, ≥ 1 basal and ≥ 1 bolus insulin claim every quarter (every 90 days) for 4 consecutive quarters after index bolus claim. Propensity score matching was used to match persistent and nonpersistent method 2 cohorts. Mean per-patient all-cause and diabetes-related medical costs (2015 U.S. dollars, excluding outpatient drugs) and health care resource use (HCRU) were calculated. For patients with hemoglobin A1c (A1c) values during baseline and post-index months 10-12, treatment success was defined as (a) A1c decrease from baseline of ≥ 1% and/or (b) baseline A1c ≥ 7% with post-index A1c < 7%. Baseline characteristics of matched cohorts were compared using standardized mean differences (SMDs). Outcome variables were compared using t-tests, chi-square tests, and generalized linear models. Characteristics of 12,882 eligible patients and 12-month persistence rates were similar as defined by method 1 (22.4%) and method 2 (21.1%). After matching, the method 2 cohorts included 2,723 and 8,169 persistent and nonpersistent patients, respectively, with well-balanced baseline characteristics (mean age 53 years; 58% men; all SMDs < 0.1). All-cause annual medical costs were lower for the persistent cohort (mean $13,499 vs. $17,362; P < 0.0001), as were annual diabetes-related costs (mean $6,392 vs. $8,376; P < 0.0001). In persistent versus nonpersistent cohorts, 11% versus 15% of patients, respectively, experienced ≥ 1 hospitalization; 21% versus 24%, respectively, had ≥ 1 ED visit; 9% versus 12%, respectively, experienced ≥ 1 diabetes-related hospitalization; and 13% versus 15%, respectively, had ≥ 1 diabetes-related ED visit (P ≤ 0.005 for all). Mean baseline A1c was similar in persistent and nonpersistent cohorts (9.7% vs. 9.6%, respectively; P = 0.63). Persistence with MDI was associated with greater mean reduction in A1c (-1.3% vs. -0.8%, respectively; P = 0.006) and greater percentages of patients achieving treatment success (55% vs. 39%, respectively, for nonpersistent; P = 0.009). Poor persistence with basal-bolus insulin therapy over 12 months of follow-up was prevalent and was associated with greater medical costs, greater HCRU, and poorer glycemic control than for patients who were persistent. Interventions are needed to improve persistence with insulin therapy and aid patients with T2DM to achieve glycemic control. Funding for this study was provided by Becton, Dickinson and Company (BD). All authors except Edelman are employees and stockholders of BD. Edelman reports board membership at Senseonics and participation in advisory board/speakers bureau at Lilly USA, MannKind, Novo Nordisk, Sanofi-Aventis U.S., Merck, and AstraZeneca, all unrelated to this study. A poster for this study was presented at the AMCP Managed Care & Specialty Pharmacy Annual Meeting 2018; April 23-26, 2018; Boston MA.