Zhennan Li, Zhihong Liu, Qing Gu, Xinhai Ni, Xiansheng Cheng, Jianguo He,  Changming Xiong

　　State Key Laboratory of Cardiovascular Disease，Fuwai Hospital, National Center for Cardiovascular Diseases，Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China

　　Objective  To explore the relationship between circulating red cell distribution width (RDW) and patients‘ conditions and prognosis in idiopathic pulmonary arterial hypertension (IPAH).

　　Methods  Patients with IPAH confirmed by right heart catheterization were enrolled consecutively in this study. Their baseline data were recorded and were followed up at the endpoint all-cause death. Baseline data were analyzed by Spearman‘s rank test and independent t-test; follow-up outcomes were analyzed with receiver operating characteristic (ROC) curves and Kaplan-Meier plots.

　　Results  76 patients (27 male cases and 49 female cases) with the mean age of (29.7±9.7) were enrolled. The correlation analysis indicated that  circulating RDW levels correlate positively with WHO functional class , right ventricular diameter, NT-ProBNP, endothelin-1 （r = 0.4, p < 0.001; r =0.29, p = 0.013; r = 0.36, p = 0.002; r =0.31, p = 0.012）, and correlate negatively with 6-MWD, left ventricular diameter, CI (r =-0.3, p = 0.029; r =-0.3, p = 0.01; r =-0.27, p = 0.019). ROC curve analysis of 2 year all-cause mortality confirmed that only RDW was the strong performer in this analysis（P = 0.003）, with an area under the curve of 0.766, a highly sensitive cut-off value 13.5% was derived to predict mortality with a sensitivity of 88.9% and a specialty of 66.7%. Survival analysis indicated that circulating RDW levels can strongly predict survival in patients with IPAH over time; high level RDW performed a poor prognosis. Independent t-test results suggested that the high level RDW group (RDW≥13.5%) have a relative higher level of WHO functional class, NT-ProBNP and endothelin-1, indicating more serious conditions and prognosis.

　　Conclusion  Circulating RDW levels correlate significantly with patients‘ conditions and prognosis in IPAH. Higher level of RDW indicates worse conditions and prognosis, high level RDW is a risk factor for adverse event in IPAH.