Oxygenated hemoglobin as prognostic marker among patients with systemic sclerosis screened for pulmonary hypertension

Background The percentage of oxygenated hemoglobin (OxyHem) in arterial blood may reflect disease severity in patients with systemic sclerosis (SSc), particularly among those with pulmonary manifestations such as pulmonary hypertension (PH). Hence, the aim of this study was to analyze the predictive value of OxyHem in SSc patients screened for PH.

Methods SSc patients screened for PH including right heart catheterisation, laboratory and clinical assessment were followed for 3.2±2.6 (median 2.6) years. OxyHem was measured by pulse oximetry. Receiver operating characteristic was performed to identify the OxyHem threshold with prognostic prediction. Kaplan-Meier analysis was performed using the defined threshold. Prognostic power was compared with known parameters of prognostic significance in SSc using uni- and multivariable analysis. Clinical parameters of patients above and below the prognostic threshold were compared by student’s t-test.

Results A total of 280 SSc patients were screened, 267 were included in the analysis (82% female, 59.8±13.4 years of age), 56 patients had manifest PH and 112 pulmonary fibrosis. In the uni- and multivariable analysis, low OxyHem was beside other clinical parameters significantly associated with a worse survival (p<0.0001). Low OxyHem at baseline was associated with hemodynamic status at baseline (p=0.042) but not at follow-up (p=0.562).

Conclusions This study detected for the first time that an OxyHem level <12.5 g/dl is a strong prognostic predictor and can possibly be used as a biomarker in SSc- patients. However, further studies are needed to confirm these results and to analyse, if OxyHem might be also useful to detect an early manifestation of PH.

Publication History

Article published online:
11 May 2022