Background Pulmonary Hypertension (PH) in scleroderma may be induced by interstitial lung disease, myocardial involvement or pulmonary arterial hypertension (PAH). PAH, due to progressive pulmonary vascular remodeling is the number one cause of death in patients with scleroderma. In pulmonary function testing, a reduced diffusing capacity (DLCO) is well recognized as a strong risk predictor of mortality in PAH. Whether expiratory flow analysis with spirometry associates with outcome is unclear.
Objectives The objective of this study was to assess spirometry as a predictor of mortality in patients with scleroderma associated pulmonary arterial hypertension.
Methods A consecutive series of patients with newly diagnosed pulmonary arterial hypertension referred to single regional referral center was reviewed. Diagnosis was based on conventional Dana Point criteria for pulmonary arterial hypertension (group 1 PH) including right heart catheterization (excluding left heart disease) and the exclusion of clinical interstitial lung disease, including negative chest imaging. Stepwise inclusion exclusion modeling was performed with mortality assessed over 5 years.
Results 440 patients with PAH (218 idiopathic (iPAH), 137 associated with connective tissue disease (cPAH, predominantly limited scleroderma), 39 with portal hypertension (PoPH) and 47 other (predominantly congenital systemic-pulmonary shunts). Forced Expiratory volumes in 1 second (FEV1) was lower in cPAH (72±18%) versus iPAH 78±16% or PoPH 77±20%; p<0.001). A decline in FEV1 was associated with known markers of disease severity (elevated right atrial pressure, low cardiac index, reduced 6 minute walk distance). A decline in FEV1 was associated with worse survival in cPAH but not other forms of PAH. For every 10% decline in FEV1, 5-year all-cause mortality increased 1. 27 fold (95% C.I 1.07-1.49; p=0.008). The association of FEV1 with mortality persisted after adjusting for age, sex, DLCO, pulmonary pressure and cardiac output.
Conclusions In scleroderma-related PAH, spirometry provides prognostic information over conventional parameters including pulmonary hemodynamics and diffusing capacity. Whether modest reductions in FEV1 may represent sub-clinical interstitial inflammation or fibrosis, pulmonary venous involvement or concomitant airway involvement warrants further testing.
Disclosure of Interest None declared