Economic impact of tobramycin in patients with cystic fibrosis in a managed care population

Abstract Objective: Guidelines recommend chronic use of tobramycin solution for inhalation (TSI) for cystic fibrosis (CF) patients with moderate-to-severe lung disease and persistent airway Pseudomonas aeruginosa. This study evaluated the economic impact of TSI in managed care CF patients. Methods: Patients (0-64 years) with 2 CF medical claims between 01/01/04-03/31/09 were identified. For TSI users, the index date was the first TSI claim in the period; for non-users, a pseudo-index date was determined and randomly assigned by simulating the distribution of index dates of TSI users. Maximum sample size was obtained for patients with 3 months pre- and 12 months post-index eligibility. Users were categorized by number of TSI prescriptions filled during 12-month post-index period as low (1 fill), medium (2-3 fills) and high adherence ( 4 fills). Differences in per member per month (PMPM) costs pre-index to post-index were analyzed using paired t-tests. Results: A total of 388 TSI users (mean age 19 years, 48% female) and 444 non-users (mean age 30 years, 54% female) met study criteria. In users, total and CF-related PMPM costs decreased $959 (17%) and $113 (3%), respectively, after starting TSI. Among TSI users, CF-related inpatient PMPM costs decreased by $1171 (49%; p = 0.01), while CF-related prescription PMPM costs increased by $992 (p