Red Blood Cell Distribution Width Predicts Responsiveness of Acute Pulmonary Vasodilator Testing in Patients with Idiopathic Pulmonary Arterial Hypertension

Background: Red blood cell distribution width (RDW) has been shown to predict clinical outcomes in cardiopulmonary vascular diseases. We investigated whether RDW is useful to predict responsiveness of acute pulmonary vasodilator testing in patients with idiopathic pulmonary arterial hypertension (IPAH).

Methods: RDW was determined in 167 IPAH patients who underwent acute pulmonary vasodilator testing. All subjects were followed up for 20 ± 10 months.

Results: Nineteen out of 167 patients (11.4%) were acute pulmonary vasodilator testing responders. Patients with lower RDW levels ≤ 13.65% (sensitivity 89.5%, specificity 52.7%; AUC: 0.747, 95% CI: 0.632 to 0.861) were more likely to have a positive response. Multivariate logistic regression analysis showed that RDW ≤ 13.65% independently predicted responsiveness of vasodilator testing in patients with IPAH (OR 18.453, 95% CI 2.279-149.391, p = 0.006). RDW correlated with disease severity evaluated by clinical parameters. Patients with increased RDW (> 13.65%) had significantly increased risk of all-cause death (Log-rank p = 0.007).

Conclusions: RDW independently predicts responsiveness of acute pulmonary vasodilator testing in patients with IPAH. RDW is associated with disease severity and all-cause death.