Patients with pulmonary arterial hypertension (PAH) who initiated inhaled treprostinil (Tyvaso®) had greater treatment adherence and persistence than those who initiated iloprost (Ventavis®), according to a real-world study comparing clinically and pharmacoeconomically relevant outcomes between the 2 drugs.

Half (50.9%) of the patients in the inhaled treprostinil cohort adhered to therapy compared with 22.6% of patients in the iloprost cohort. These proportions increased to 70.1% and 33.9% when the authors used a less stringent adherence threshold.

In addition, patients in the inhaled treprostinil cohort had a 58% reduced risk for discontinuation over the 12-month post-index period compared with patients in the iloprost cohort, as shown by multivariable analysis adjusted for age, sex, race, geographic region, coverage type, Quan-Charlson Comorbidity Index category, PAH medication regimen, and baseline hospitalizations.

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However, these findings do not necessarily mean superior performance of inhaled treprostinil in terms of efficacy and/or tolerability, the study’s authors explained.

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“Given the lack of head-to-head clinical data comparing inhaled treprostinil and iloprost, it is not possible to definitively attribute these differences to the relative efficacy and/or tolerability of these agents,” they wrote.

“Instead, it is likely that the difference in dosing frequency and duration (8-12 minutes total daily treatment duration over 4 sessions for inhaled treprostinil vs 24-90 minutes total duration over 6-9 sessions for iloprost) was a major contributor to improved adherence and persistence.”

Burger et al measured adherence using the proportion of days covered and considered that patients adhered to treatment if the proportion of days covered was 0.8 or higher. A less stringent adherence threshold of 0.5 or higher was used in some analyses. Treatment persistence was considered when patients showed no gap of more than 60 days in treatment.


Burger CD, Wu B, Classi P, Morland K. Inhaled treprostinil vs iloprost: comparison of adherence, persistence, and health care resource utilization in patients with pulmonary arterial hypertension. J Manag Care Spec Pharm. 2023;29(1):101-108. doi:10.18553/jmcp.2023.29.1.101