Increased respiratory drive relates to severity of dyspnea in systemic sclerosis.

Background: Dyspnea may be a presenting symptom in progressive systemic sclerosis (SSc). Respiratory drive (mouth occlusion pressure, MOP, at rest and during CO2 rebreathing, 7% CO2, 93% O2) is a major determinant of dyspnea and may relate to the magnitude of dyspnea.

Methods: In a prospective design, MOP at 0.