Clinical characteristics and risk factors of chronic obstructive pulmonary disease complicated with pulmonary hypertension at different altitudes

Abstract Background:Pulmonary hypertension (PH) is a common complication in patients with chronic obstructive pulmonary disease (COPD) and is closely related to poor prognosis. At present, researches about the risk factors of PH in COPD patients are limited, especially the human population at high altitude (HA). Objectives: To investigate the differences of clinical characteristics and related risk factors of patients with COPD/COPD-PH from low altitude (LA, 600m) and HA (2200m). Methods: We performed a cross-sectional survey of 228 COPD patients of Han nationality admitted to respiratory department of Qinghai People's Hospital (N=113) and West China Hospital of Sichuan University (N=115) From March 2019 to June 2021. PH was defined as a pulmonary arterial systolic pressure (PASP) >36 mmHg measured by transthoracic echocardiography (TTE). Results: In this study, the proportion of PH in COPD patients at HA was higher than that at LA (60.2% vs 31.3%). COPD-PH patients at HA showed significantly different in baseline characteristics, laboratory tests and pulmonary function test. Multivariate logistic regression analysis indicated that the independent related factors of PH in COPD patients are different between HA and LA. Conclusions: The proportion of COPD-PH at HA is higher than LA. At LA, increased BNP( B-type natriuretic peptide) and DB(direct bilirubin) were independent risk factors for PH in COPD patients. While at HA, higher BMI was independent protective factor and increased DB was independent risk factor for PH in COPD patients.