Predictive Value of Smoking Index Combined with NT-proBNP for Patients with Pulmonary Hypertension Due to Chronic Lung Disease: A Retrospective Study

Purpose: Smoking is a major risk factor for the group 3 PH. NT-proBNP is a biomarker for risk stratification in PH. This study aims to investigate the effects of smoking status and smoking index (SI) on group 3 PH and to evaluate the value of SI and SI combined with NT-proBNP in early diagnosis and prediction of disease severity.
Patients and Methods: Four hundred patients with group 3 PH at the First Hospital of Shanxi Medical University between January 2020 and December 2021 were enrolled and divided into two groups: mild (30 mmHg ≤ pulmonary artery systolic pressure (PASP)≤ 50 mmHg) and non-mild (PASP > 50 mmHg). The effect of smoking on group 3 PH was analyzed using univariate analysis, and logistic analysis was conducted to evaluate the risk of group 3 PH according to smoking status and SI. Spearman correlation coefficient was used to test the correlation between SI and the index of group 3 PH severity. The predictive value of SI was evaluated using a receiver operating characteristic (ROC) curve.
Results: Correlation and logistic analyses showed that SI was associated with PH severity. Smoking status (P=0.009) and SI (P=0.039) were independent risk factors for non-mild group 3 PH, and ROC showed that the predictive value of SI (AUC:0.596) for non-mild PH was better than that of the recognized pro-brain natriuretic peptide (NT-proBNP) (AUC:0.586). SI can be used as a single predictive marker. SI and NT-proBNP can be formulated as prediction models for screening non-mild clinical cases (AUC:0.628).
Conclusion: SI is a potentially ideal non-invasive predictive marker for group 3 PH. SI and NT-proBNP could be used to develop a prediction model for screening non-mild PH cases. This can greatly improve the predictive specificity of the established PH marker, NT-proBNP.

Keywords: smoking index, NT-proBNP, pulmonary hypertension, chronic lung disease, predictive value