Meta-analysis Of The Correlation Between RDW And Pulmonary Hypertension

Background:Pulmonary hypertension (PH) has been defined as an increase in mean pulmonary arterial pressure (PAP) ?25mmHg at rest,as assessed by right heart catheterization.The pathogenesis of PH is complex and is related with hypoxia-dependent pulmonary vasoconstriction with secondary vascular remodeling in many cases,leading to a progressive increase in pulmonary vascular resistance and right ventricular failure.If the presence of this disease can be detected early,certain interventions can be taken to delay or even avoid the further development of pulmonary hypertension.Although the association of red cell distribution width RDW with PH is well known,there are controversies as to whether red cell distribution width RDW is associated with the severity,or prognosis of PH.However,there is no systematic review and meta-analysis on these topics.Aims:To investigate the association of RDW with pulmonary hypertension (PH) in term of severity,and prognosis of PH.Methods:The authors systematically reviewed articles from databases,two researchers screened the literature and extracted relevant data based on inclusion and exclusion criteria.Literature quality evaluation was conducted by the tool of NOS scale.The corresponding effect model was analyzed according to the I~2 heterogeneity test.The difference of P<0.05 was statistically significant.And finally conducted meta-analyses as follows:(1)association of red cell distribution width (RDW) levels with the presence of PH;(2)association of red cell distribution width (RDW) levels with prognosis of PH,in terms of hazard ratio of death.(3)association of red cell distribution width (RDW) levels with severity of PH,in terms of pulmonary arterial pressure.Results:Twenty-two studies published were included in this study,among the 22 studies,13 studies focus on the relationship between red cell distribution width (RDW) levels with the presence of PH,the results showed that the level of red cell distribution width RDW was higher in subjects with PH than subjects without PH,the difference was statistically significant (SMD=0.94,95%CI:0.83~1.05,P<0.0001) .About 8studies focus on the association of red cell distribution width (RDW) levels with prognosis of PH,in terms of the hazard ratio of death.Results indicated that among the PH patients,the mortality of patients with high RDW level was significantly higher than that of patients with low RDW level in the RDW experimental group,the difference was statistically significant (RR=2.06,95%CI:1.82~2.33,P=0.000) .And3 studies research the association of red cell distribution width (RDW) levels with severity of PH,in terms of the pulmonary arterial pressure,analysis showed that the RDW level in the patients with severe,moderate and mild pulmonary hypertension was higher than that in the control group without pulmonary hypertension,and the difference was statistically significant (SMD=3.00,95%CI:2.70~3.31,P=0.0000) , (SMD=2.24,95%CI:1.99~2.49,P=0.0000) , (SMD=1.42,95%CI:1.21~1.64,P=0.0000) ,Therefore,we concluded that there was a significant difference in RDW between the control group and the experimental group with pulmonary hypertension,and the higher the RDW level,the higher the pulmonary systolic blood pressure.This indicates that RDW may be one of the indicators to evaluate the severity of pulmonary hypertension.Conclusions:The RDW level in PH patients was significantly increased regardless the category of PH.Existing evidence suggests that the level of RDW may be related to the onset of PH.Moreover,high RDW level is negatively correlated with the prognosis in pulmonary hypertension patients.Therefore,RDW is related to disease severity and may be used to predict survival in patients with PH,and maybe a predictor and a prognostic factor for patients with pulmonary hypertension.However,large sample size,multi-center,high-quality,long-term RCT studies are still needed to further confirm its prediction and prognosis.