Patients (0-64 years) with >=2 CF medical claims between 01/01/04-03/31/09 were identified. 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.
Interventions
tobramycin solution for inhalation (TSI)
Outcome measures
This study evaluated the economic impact of TSI in managed care CF patients. 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.
Main results
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<0.01). CF-related inpatient PMPM costs decreased by $381 (38%; p=0.16) for low and $1425 (50%; p=0.21) for medium users and decreased by $1829 (51%; p=0.02) for high users.
Authors' conclusions
All-cause and CF-related PMPM medical costs significantly decreased after TSI initiation. Among TSI users, total healthcare costs decreased, although not significantly, due to PMPM increases in prescription costs. A trend towards greater decrease in inpatient PMPM costs was observed with increasing TSI adherence.