Protocol: Prospective observational study investigating the prevalence and clinical outcome of portopulmonary hypertension in Japanese patients with chronic liver disease

BACKGROUND: Portopulmonary hypertension (PoPH) is a subtype of the pulmonary arterial hypertension (PAH) associated with portal hypertension. There is a dissociation between the proportion of PoPH in PAH and that of PoPH in patients with liver cirrhosis, suggesting PoPH underdiagnosis and an incomplete understanding of this entity in the clinical setting. Specifically, real-world data in Japan is largely unknown as compared with in Europe and the United States. The present study aims to elucidate the prevalence and etiology of PoPH in Japanese patients with chronic liver disease. METHODS AND DESIGN: In this prospective, single-center, observational investigation of PoPH patients with chronic liver disease, a targeted 2,500 Japanese adult patients regularly visiting Shinshu University Hospital in Matsumoto, Japan, for chronic liver disease will complete a standardized questionnaire on the presence of PoPH symptoms. If the respondent has signs of possible PoPH, ultrasound echocardiography (UCG) will be performed as a primary screening. In the case that UCG findings indicate pulmonary hypertension, the patient will be referred to a cardiologist for further evaluation, whereby a definitive diagnosis PoPH can be made. PoPH prevalence and etiology will be investigated at the time of diagnosis. Afterwards, patients with PoPH will be followed for five years for determination of survival rate. DISCUSSION: This study will reveal the prevalence, etiology, and 5-year survival rate of PoPH in Japanese patients with chronic liver disease. TRIAL REGISTRATION: This study is being performed at Shinshu University following registration as UMIN 000042287 on October 29, 2020.