HP and obstructive sleep apnea syndrome: Of the 41 eligible participants, 31.7% had a diagnosis of obstructive sleep apnea (OSA) and 34.1% had a diagnosis of pulmonary hypertension at the time of NHD testing; ≥15% of data for ARC, total bilirubin, ferritin, LDH, eGFR, CRP, haptoglobin were missing; <3% of data for all other variables in this analysis.