Resource Use Evaluation of Tobramycin Formulations in a State Medicaid Program

Patients with cystic fibrosis (CF) often suffer from chronic infection with Pseudomonas aeruginosa. For patients with CF, 6 years of age and older, with P aeruginosa persistently present in cultures of the airways, the Cystic Fibrosis Foundation recommends the chronic use of inhaled tobramycin to reduce exacerbations. To ease treatment burden, a new dry powder formulation was developed. The objective of this research was to compare resource utilization between tobramycin inhaled solution (TIS) and a new tobramycin dry powder (TIP) formulation in a state Medicaid program.

Members that switched from TIS to TIP were matched to TIS-only beneficiaries via propensity score based on age, sex, race, and residence location. The outcomes (tobramycin reimbursement, inpatient hospital reimbursement, additional antibiotic therapy reimbursement, length of inpatient stays, odds of adherence, odds of inpatient hospital stay, and additional mean days of antibiotic therapy) were assessed by using multivariable regression and included baseline clinical surrogates.

No difference was found between 54 matched members for tobramycin reimbursement, length of inpatient stays, odds of adherence, or odds of hospital stay. Cost of additional antibiotic therapy was higher for TIP (+$518, p < 0.001) and inpatient reimbursement was higher for TIS (+$503, p = 0.031). Additional mean days of antibiotic therapy were lower for TIP (8.6 vs. 10.1, p = 0.374), but was not statistically significant.

In patients that switched from TIS to TIP, an increase in cost of additional antibiotic therapy was observed, while inpatient costs were lower. Research should be considered in larger populations to fully determine the impact of the new dry powder formulation on overall resource use and outcomes.