Real-world clinical practice of pulmonary arterial hypertension in Japan: Insights from a large administrative database

Pulmonary arterial hypertension (PAH) is a fatal disease that often occurs at an early age. In recent years, aggressive treatment with multiple drugs from the early-stage diagnosis is expected to improve the prognosis. Indeed, a high rate of initial combination therapy and excellent treatment outcomes have been reported from specialized centers for PAH in Japan. However, information on PAH epidemiology, including non-PAH specialized centers in Japan, is unclear. To address the above, we conducted a retrospective observational cohort study from April 2008 to September 2020 using realworld evidence from a large-scale administrative database (Medical Data Vision) to examine baseline characteristics, comorbidities, and treatment profiles of Japanese patients with PAH. Five hundred and eighteen patients with PAH (treatment-naive PAH, age 67.2 +/- 15.9) were identified through our comprehensive approach which combined PAH disease codes, medications, and diagnostic procedures. Moreover, we showed that a larger proportion of patients received monotherapy in their initial treatment (66%) compared to those receiving combination therapy (34%). During the 1-year follow-up after PAH diagnosis, 13% of patients increased their PAH medications while other patients either decreased their PAH medications (6%) or discontinued PAH treatment (27%). The 3- and 5-year event- free survival rates of all-cause death were 72% and 64%, respectively. This is the first large-scale administrative database study that provides insights into real-world PAH management in Japan. This study highlighted a different PAH clinical landscape which included a larger portion of the elderly population, higher initial monotherapy treatment, and lower survival rates than previous studies.