Economic Evaluation of Tobramycin Inhalation Powder for the Treatment of Chronic Pulmonary Pseudomonas aeruginosa Infection in Patients with Cystic Fibrosis

Abstract

Background: Chronic lung infection with Pseudomonas aeruginosa occurs in approximately 50% of patients with cystic fibrosis (CF). This infection further compromises lung function, and significantly contributes to the increased healthcare costs.

Objectives: Inhaled tobramycin, used to manage P. aeruginosa infection in CF patients, is available as powder (tobramycin inhalation powder, TIP) and solution (tobramycin inhalation solution, TIS). Evidence suggests increased adherence with the use of TIP over TIS. Hence, this analysis aimed to evaluate the potential pharmacoeconomic benefit of increased adherence with TIP over TIS in the US setting.

Methods: A patient-level simulation model was developed to compare TIP with TIS. Both costs and benefits were predicted over a 10-year time horizon from a payer's perspective, and were discounted annually at 3%. All costs were presented in 2016 US dollars.

Results: TIP was associated with greater quality-adjusted life-years (by 0.27) and lower total costs (by US$36,168) as compared with TIS over a 10-year time horizon. TIP-treated patients experienced a decreased mean number of exacerbations than TIS-treated patients (39.24 vs 50.20). Furthermore, administration of TIP via the T-326 Inhaler was associated with significant cost savings per patient, because of the nebulizer required for administering TIS (by US$1596) and exacerbation costs (by US$76,531). Probabilistic sensitivity analysis showed that TIP was dominant over TIS in 100% of the simulations.

Conclusion: TIP is likely to be a more cost-effective treatment than TIS, and therefore may reduce the economic burden of CF.

Fig. 1

Model structure. Baseline characteristics used in the model were age, gender, P. aeruginosa infection, sputum, crackles, wheezing, sinusitis, elevated liver function tests, and pancreatic insufficiency. Other model inputs included: mean improvement in FEV₁ % predicted 3.1% for TIP and 2.3% for TIS; severe exacerbation rate at 6 months with TIP (high adherence): FEV₁ % <40–1.31, FEV₁ % 40–70–0.68, FEV₁ % >70–0.43; severe exacerbation rate at 6 months with TIS (low adherence) based on odds ratio of 0.4: FEV₁ % <40–2.04, FEV₁ % 40–70–1.23, FEV₁ % >70–0.85; mild exacerbation rate at 6 months (considered to be same for TIP and TIS due to lack of data): FEV₁ % <40–1.32, FEV₁ %: 40–70–0.99, FEV₁ % >70–1.09. FEV ₁ % predicted percent predicted forced expiratory volume in 1 s, TIP tobramycin inhalation powder, TIS tobramycin inhalation solution, P. aeruginosa Pseudomonas aeruginosa

Fig. 2

Comparison of health outcomes for treatment with tobramycin inhalation powder and tobramycin inhalation solution. ^aMean difference; ^b95% confidence intervals

Fig. 3

Comparison of average costs for treatment with tobramycin inhalation powder (TIP) and tobramycin inhalation solution (TIS). ^aConfidence intervals. Costs as well as confidence intervals for regular follow-up were the same for the two treatments

Fig. 4

a One-way sensitivity analyses—tornado chart. b Probabilistic sensitivity analysis. QALYs quality-adjusted life-years, FEV ₁ forced expiratory volume in 1 s, TIP tobramycin inhalation powder, TIS tobramycin inhalation solution, ICER incremental cost-effectivenes ratio