Tadalafil therapy and health-related quality of life in pulmonary arterial hypertension

Background: Pulmonary arterial hypertension (PAH) is a rare, progressive lung disorder that impairs performance of daily activities and quality of life (QoL), leading to right heart failure and death. Treatment options include prostanoids, endothelin antagonists, and phosphodiesterase type 5 inhibitors (e.g., tadalafil). Currently there is no cure for PAH, but tadalafil has improved exercise capacity in these patients. Objectives: To explore the effect of tadalafil on health-related quality of life (HRQoL) measures. Research design and methods: The Pulmonary Arterial Hypertension and Response to Tadalafil (PHIRST) clinical trial examined the efficacy and tolerability of tadalafil for the treatment of PAH. The impact of tadalafil on HRQoL and exercise capacity, as measured by 6-minute walk test (6MW test), was also examined. Change from baseline to last non-missing post-baseline was examined for the SF-36, EQ-5D, and 6MW test, along with the relationship between HRQoL and 6MW test performance. Results: Tadalafil 40 mg showed significant improvement over placebo for six of eight SF-36 domains, and EQ-5D index scores. Also, the tadalafil 40-mg group showed significant improvement over placebo on the 6MW test (p < 0.001), but no clear relationship was found between 6MW test performance and HRQoL. Conclusion: Results suggest that tadalafil 40 mg may significantly improve HRQoL and exercise capacity for PAH patients. Limitations of this study include its relatively short nature limited to 16 weeks and the relative heterogeneity of the study population.