Abstract
Background: Change in diffusing capacity for carbon monoxide (DLCO) is a more powerful predictor of outcomes than baseline DLCO in connective tissue disease (CTD)-associated pulmonary arterial hypertension (PAH).
Aims and Objectives: We sought to validate these findings in a larger, multi-center CTD-APAH cohort.
Methods: CTD-APAH patients (pts) in the Registry to EValuate Early And Long Term PAH Management (REVEAL), comprising 3515 pts with PAH from 56 US centers, were divided into 3 cohorts based on change in DLCO over time: 1) decreased by >10% (DLCOdec), 2) unchanged within ±10% (DLCOstab), 3) increased by >10% (DLCOinc). Two-year survival after second DLCO assessment was evaluated.
Results: 249 CTD-APAH pts were analyzed. Most pts were women (87.9%), with Ssc-APAH (73.9%), functional class II & III symptoms (77.9%), and on PAH therapies (83.9%). While 66.3% of pts were stable over time, 25.3% had reduced (-20.1±12.4%) and 8.4% improved (25.1±18.2%) DLCO. Mean time between DLCO measurements did not differ between DLCOdec and DLCOinc pts (34.6±28.6 vs. 29.7±25.2 mos., P>0.05). All deaths (80) occurred in DLCOdec and DLCOstab cohorts. The DLCOinc cohort had the best 24-month survival (log-rank p=0.007, DLCOinc vs. DLCOstab). Multivariable analysis showed DLCOdec as a predictor of worst survival (HR 2.8, CI=1.65-4.73, P<0.001).
Conclusion: Increase in DLCO by >10% was associated with improved outcomes in CTD-APAH. Identification of mechanisms and role of therapies in DLCO enhancement needs further investigation and may provide significant insights into future clinical care of patients with PAH.
- © 2012 ERS