Inhaled aztreonam lysine versus inhaled tobramycin in cystic fibrosis an economic evaluation

Rationale: Pseudomonas aeruginosa infection is a significant cause of morbidity and mortality in patients with cystic fibrosis and is associated with a high economic burden. A recently published comparator trial demonstrated that outcomes in patients with cystic fibrosis with chronic P. aeruginosa infections switched from tobramycin solution for inhalation to aztreonam lysine for inhalation were better than those of patients who continued on tobramycin. Objectives: To compare overall costs of treatment of chronic inhaled tobramycin and aztreonam lysine in patient with cystic fibrosis who have chronic Pseudomonas infection, taking differences in outcomes into account. Methods: A cost-effectiveness analysis with a 3-year time horizon was performed to simulate the economic consequences of either treatment from the perspective of a third party payer in the United States. We extrapolated results from the comparator trial and used data regarding clinical outcomes, quality of life, and costs from published literature and proprietary databases. A Markov structure was used to consider transitions between health states, defined principally by levels of percent predicted of FEV<inf>1</inf>. Extensive scenario and probabilistic sensitivity analyses were performed. Measurements and Main Results: Use of aztreonam lysine for inhalation was associated with an average cost saving of $41,947 per patient over 3 years, as well as greater quality-adjusted life-years and total life-years. Scenario analyses demonstrated that these findings were robust to changes in key assumptions. Conclusions: It appears, with high likelihood, that the use of aztreonam solution for inhalation is associated with cost savings, an increase in quality-adjusted life-years, and improved clinical outcomes among patients with extensive prior use of tobramycin solution for inhalation who are naive to inhaled aztreonam lysine.