Diagnostic value of combined FVC%/DLCO% and echocardiography in connective tissue disorder‑associated pulmonary hypertension.

The main objective of the present study was to investigate whether forced vital capacity (FVC)%/diffusing capacity of the lungs for carbon monoxide (DLCO)% can be used to predict the presence of pulmonary hypertension (PH) in connective tissue disorders (CTDs). For this purpose, a total of 53 individuals who were diagnosed with CTDs and had undergone right heart catheterization between July, 2019 and July, 2022 were included in the present study. Based on the mean pulmonary artery pressure (mPAP) measured during right heart catheterization, the participants were divided into the PH and non-PH groups. The differences in demographic characteristics, including sex, age, body mass index, smoking index, FVC%/DLCO% and pulmonary artery systolic pressure (PASP) were determined by echocardiography; moreover, the 6-min walk distance, plasma brain natriuretic peptide (BNP) levels, white blood cell count, red blood cell distribution width, erythrocyte sedimentation rate and C-reactive protein levels were compared between the two groups to identify independent predictors of PH. The independent predictors were subsequently evaluated for their correlation with mPAP to assess their predictive value for PH. FVC%/DLCO%, echocardiographic PASP, and plasma BNP levels were identified as independent predictors of PH. FVC%/DLCO% and echocardiographic PASP exhibited a significant correlation with mPAP, while the correlation between plasma BNP and mPAP levels was not statistically significant. The area under the curve (AUC) value for FVC%/DLCO% alone in predicting PH was 0.791, with an optimal diagnostic threshold of 1.35, a sensitivity of 0.794 and a specificity of 0.789. The AUC for echocardiographic PASP alone in predicting PH was 0.783, with an optimal diagnostic threshold of 39.5 mmHg, a sensitivity of 0.794 and a specificity of 0.684. When combined, the AUC of the two factors in predicting PH was 0.872, with a sensitivity of 0.941 and a specificity of 0.684. Collectively, the data of the present study indicate that FVC%/DLCO% may be used as a predictive factor for CTD-PH, and its combined application with echocardiographic PASP measurement may provide additional evidence for the clinical diagnosis of CTD-PH.