Clinical characteristics and risk factors of pulmonary hypertension associated with chronic respiratory diseases: a retrospective study.

Background: Chronic respiratory disease-associated pulmonary hypertension (PH) is an important subtype of PH, which lacks clinical epidemiological data in China. Methods: Six hundred and ninety three patients hospitalized from 2010 to 2013 were classified by echocardiography according to pulmonary arterial systolic pressure (PASP): mild (36 <= PASP <50 mmHg); moderate (50 <= PASP < 70 mmHg) and severe (PASP >= 70 mmHg). Results: Dyspnea (93.51%) was the most common symptom. Hemoptysis observed in the severe group (6.42%) was significantly higher than the other two groups (P<0.05). COPD (78.35%), lung bullae (44.16%), tuberculosis (including obsolete pulmonary tuberculosis) (38.82%), and bronchiectasis (30.45%) were frequently present. Mild group occupied the highest proportion (84.7%) in COPD, while severe group occupied the highest proportion (19.3%) in pulmonary embolism (P<0.01). Age, partial pressure of oxygen (PaO2), hematocrit (HCT), partial pressure of carbon dioxide (PaCO2), increase of N-terminal pro brain natriuretic peptide (NT-proBNP) and right ventricular (RV) diameter (>20 mm) were associated with moderate-to-severe PH, while RV [odds ratio (OR) = 3.53, 95% CI, 2.17-5.74], NT-proBNP (OR=2.44, 95% CI, 1.51-3.95), HCT (OR=1.03, 95% CI, 1.00-1.07) and PaCO2 (OR= 1.01, 95% CI, 1.00-1.03) were independent risk factors. Conclusions: PH related to respiratory diseases is mostly mild to moderate, and the severity is associated with the category of respiratory disease. Increased HCT can be an independent risk factor for PH related to chronic respiratory diseases.