Objective: Our goal was to determine if whole blood viscosity (WBV) can be used to predict the risk of pulmonary arterial hypertension (PAH) in patients with systemic sclerosis (SSc).
Methods: Patients with SSc were analyzed. Out of 107 patients, 26 patients, found to have confirmed diagnosis of PAH, were classified as those with (n = 26, PAH group) and without PAH (n = 81, non-PAH group). We calculated estimated WBV at both high (HSR) and low shear rates (LSR) from hematocrit and total serum protein levels.
Results: Total protein levels were significantly higher and the anti-centromere antibody (ACA) was more frequent in the PAH group. Furthermore, anti-topoisomerase antibody (anti-scl-70) was significantly less frequent in the PAH group. The WBV values were significantly higher at HSR (16.68 ± 0.38 vs. 16.24 ± 0.58; p < 0.001) and at LSR (51.81 ± 7.21 vs. 42.97 ± 11.76; p < 0.001) in PAH group. The multivariate analysis revealed that the WBV at both shear rates independently designated the presence of PAH in SSc patients. The ROC curve showed that the sensitivity and specificity of LSR and HSR were 92.3% and 61.7% (AUC 0.759, p < 0.001), and 88.5% and 65.4% (AUC 0.770, p < 0.001) with a cutoff value of 43.56 and 16.32 for WBV, respectively.
Conclusion: Higher WBV levels in SSc patients were an independent indicator for PAH development in this cohort. WBV-LSR and WBV-HSR values might help exclude the PAH possibility in patients diagnosed with SSc and remain as an independently associated biomarker for follow-up of these patients for future risk of PAH development. Findings remain to be confirmed by other cohorts.Key Points• The most important cause of morbidity and mortality in systemic sclerosis patients is considered to be pulmonary arterial hypertension.• When the symptoms of PAH are not recognized earlier in the course of the SSc, the prognosis might be worse.• Higher whole blood viscosity levels in scleroderma patients with PAH was an independent indicator for PAH development.
Keywords: Pulmonary arterial hypertension; Systemic sclerosis; Whole blood viscosity.