Abstract
OBJECTIVE: To analyse the clinical features of AECOPD (acute exacerbation of chronic obstructive pulmonary disease) at different altitudes and GOLD (global initiative of chronic obstructive lung disease) stages in high-altitude regions. METHOD: This was a retrospective cross-sectional study. Patients diagnosed with AECOPD through pulmonary function tests and hospitalised in People's Hospital of the Tibet Autonomous Region from September 2018 to March 2024 were included. Patients were divided into three groups according to their native residential altitude prior to onset: low-altitude group (169 cases, 2700-3700 m), mid-altitude group (77 cases, 3700-4000 m) and high-altitude group (97 cases, 4000-4800 m). Patients were also classified into three groups according to their FEV1%pred in pulmonary function test on admission: mild (91 cases, FEV1%pred ≥80%), moderate (171 cases, 50%≤FEV1%pred <80%) and severe/very severe (81 cases, FEV1%pred <50%). RESULT: (1) Altitude comparison: the mid-altitude group showed lower values for age (66.49±8.13 years), hospital length of stay (9.79±3.20 days) and time since diagnosis (1.89±1.73 years) compared with the low-altitude group. On the other hand, the mid-altitude group showed higher SPO(2) (82.35±5.17%) and pulmonary fibrosis prevalence (40.26%) than the low-altitude group. The high-altitude group had higher rates of emphysema (56.70%) and pulmonary hypertension (51.55%) compared with the low-altitude group. The high-altitude group showed lower levels of B-type natriuretic peptide (BNP) (185.76±195.19 pg/mL), red blood cell count (RBC) (5.77±0.97×10(12)/L), D-dimer (D-D) (1.01±1.33 mg/L) and fibrinogen degradation product (FDP) (3.11±1.38 mg/L) than the low-altitude group. The high-altitude group had a longer time since diagnosis (2.63±3.39 years) than the mid-altitude group and lower SPO(2) (80.01±7.60%), rate of pulmonary fibrosis (22.68%) and BNP level (185.76±195.19 pg/mL) compared with the mid-altitude group. These differences were statistically significant (p<0.05). No significant differences were found for other variables between altitude groups (p>0.05). (2) GOLD staging comparison: the moderate group had higher values for the time since diagnosis (2.61±2.95 years), prevalence of emphysema (50.29%), pulmonary fibrosis (28.07%), pulmonary hypertension (45.61%), cor pulmonale (40.94%), and levels of C-reactive protein (CRP) (23.89±34.01 mg/L) and procalcitonin (PCT) (0.32±0.71 ng/mL) than the mild group. The moderate and severe/very severe groups had lower SPO(2) (80.77±6.71%, 78.38±8.31%) than the mild group. The severe/very severe group had higher rates of emphysema (54.31%), pulmonary bullae (28.40%), pulmonary hypertension (59.26%), cor pulmonale (56.79%), and levels of CRP (20.92±29.92 mg/L) and PCT (0.81±3.43 ng/mL) than the mild group. The severe/very severe group had a shorter time since diagnosis (2.27±1.97 years) than the moderate group. The severe/very severe group also had a higher percentage of males (72.84%), pulmonary hypertension (59.26%), cor pulmonale (56.79%), and levels of BNP (392.50±728.31 pg/mL) and PCT (0.81±3.43 ng/mL) compared with the moderate group. These differences were statistically significant (p<0.05). No significant differences were found for other variables between GOLD groups (p>0.05). CONCLUSION: In high-altitude regions, as the altitude increases, body mass index, the proportion of male patients, rate of emphysema and pulmonary hypertension become more prominent in AECOPD patients. Higher GOLD stages are associated with longer hospital stays, higher smoking indices and greater prevalence of emphysema, pulmonary fibrosis, pulmonary hypertension and cor pulmonale. Lower SPO(2) is associated with higher levels of RBC, haemoglobin, haematocrit (HCT), CRP, PCT, white blood cell count and neutrophil%. However, as native residential altitude increases, BNP, RBC, HCT, D-D and FDP decrease.