Clinical and Radiological Features of COPD Patients Living at ≥3000 m Above Sea Level in the Tibet Plateau.

Background: COPD at high altitude may have different risk factors and unique clinical and radiological phenotypes. We aimed to investigate the demographic data, clinical and radiological features of COPD patients permanently residing at the Tibet Plateau (≥3000 meters above sea level). Methods: We conducted an observational cross-sectional study which consecutively enrolled COPD patients visiting the outpatient of Respiratory Medicine at Tibet Autonomous Region People's Hospital from January 2018 to March 2021. All patients were Tibetan permanent residents aging ≥40 years and met the diagnosis of COPD according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines. Data including demographic characteristics, altitude of residence, risk factors, respiratory symptoms, comorbidities and medications, as well as computed tomography (CT) measurements were collected. Results: Eighty-four patients with definite COPD were enrolled for analysis. Their mean age was 64.7 (±9.1) years. All patients lived at ≥3000 m above sea level and 34.5% of them lived at ≥4000 m. About 8.3% of the patients were current smokers and 44.0% were ex-smokers. Up to 88.1% of the patients reported long-term exposure to indoor biomass fuels. Most of the patients were classified as having mild-to-moderate (GOLD I: 27.4%; GOLD II: 51.2%) COPD, while 89.3% had a CAT score ≥10. Only 36.9% of the patients received regular long-term medications for COPD in the past year, in whom ICS/LABA and oral theophylline were the most common used pharmacological therapy. On CT scanning, the majority of our patients (70.7%) showed no or minimal emphysema, while signs of previous tuberculosis were found in 45.1% of the patients. Conclusion: COPD patients living at the Tibet Plateau had a heavy respiratory symptom burden, but most of them did not receive adequate pharmacological treatment. Indoor biomass fuel exposure and previous tuberculosis were prevalent, while the emphysema phenotype was less common in this population.