Early intervention in pulmonary arterial hypertension associated with systemic sclerosis (SSc) may improve its prognosis. We aimed to establish an algorithm to detect mean pulmonary artery pressure (mPAP) > 20 mmHg using non-invasive examinations in SSc patients by modifying the DETECT algorithm. This study included SSc patients who underwent right heart catheterization (RHC) in our hospital during 2010-2018. Following variables were assessed for performance to predict mPAP ≥ 25 mmHg or > 20 mmHg; anti-centromere or U1-RNP antibody, plasma BNP level, serum urate level, right axis deviation, forced vital capacity (FVC)/diffusing capacity for carbon monoxide (DLCO) ratio, and tricuspid regurgitation velocity. Of 58 patients enrolled in this study, 24 had mPAP of ≥ 25 mmHg and 9 had mPAP of 21-24 mmHg. Among variables tested, only FVC/DLCO elevated similarly in patients with mPAP of ≥ 25 mmHg (median 2.5) and those with mPAP of 21-24 mmHg (median 2.5) compared to those with mPAP of ≤ 20 mmHg (median 1.5). Given the particularly good correlation between DLCO and mPAP of > 20 mmHg, each variable was weighted according to its odds ratio and the total weighted score was calculated. The total weighted score exhibited a good predictive performance for mPAP of > 20 mmHg with its sensitivity of 87.5% and specificity of 92%. Among conventional risk factors for PAH, decreased DLCO may predict mPAP > 20 mmHg with priority in SSc patients. Weighting DLCO may improve the performance of screening algorithm for early SSc-PAH.
Keywords: FVC/DLCO; Pulmonary arterial hypertension; Screening; Systemic sclerosis.