Abstract: Objective To investigate the etiological composition of patients with pulmonary arterial hypertension （PAH） and to analyze their hospitalization outcome. Methods PAH patients admitted to the 3 hospitals in Meishan area from January 2019 to December 2021 were enrolled in the study, and the etiological composition of PAH patients was analyzed according to the 2008 Dana Point Classification of PAH based on patient medical record data and diagnosis. The characteristics and hospitalization outcomes of the patients were analyzed, and the influencing factors of the hospitalization outcome were analyzed by univariate and multivariate analysis methods. Results A total of 1 748 PAH patients were included for analysis. There were 624 cases （35.70%） of arterial PAH, 811 cases （46.40%） of left heart disease-related PAH, 286 cases （16.36%） of respiratory diseases or hypoxia-related PAH, 23 cases （1.32%） of chronic thrombotic PAH, and 4 cases （0.23%） of PAH caused by unknown causes or multiple factors. There were statistically significant differences in the etiological distribution of PAH patients with different gender, ages, and years （all P < 0.01）. There were 1 295 cases （74.08%） of good outcomes and 453 cases （25.92%） of adverse outcomes （including the abandonment of treatment or death）. Multivariate Logistic regression analysis showed that the risk factors affecting the adverse outcomes of PAH patients were female （OR= 4.436）, age increase （OR= 7.396）, the disease was associated with the arterial type （OR= 2.349）, left heart disease （OR=1.689）, and respiratory system disease or hypoxia （OR=1.379）, the elevation of PAH grade （OR=1.499）, course of disease > 60 months （OR=3.747）, complications （OR=2.149）, abnormal PaO₂ （OR=2.654）, and abnormal PaCO₂ （OR=1.319）. Conclusions PAH is most common in patients aged 41 to 50 years and is more common in women. Arterial PAH and left heart disease-related PAH are the most common causes of PAH. The incidence of adverse outcomes in PAH patients is high, and there are significant differences in hospitalization outcomes among patients with different characteristics.

Key words: Pulmonary arterial hypertension, Etiological composition, Hospitalization outcome, Factor analysis