Association of altitude and eosinophil with the one-year mortality of acute exacerbation of chronic obstructive pulmonary disease: a cohort study.

BACKGROUND

Altitude and eosinophil (EOS) are closely related to chronic obstructive pulmonary disease (COPD). There are limited studies on the association of altitude and EOS with mortality of COPD patients. Our aim was to explore the association of altitude and EOS with one-year all-cause mortality of patients hospitalized for acute exacerbation of COPD (AECOPD).

METHODS

A total of 351 inpatients with AECOPD in two hospitals from 2021 to 2022 were enrolled and divided into two groups based on the altitude and followed up for one year. Logistic and Cox regression analyses were used to determine the relationship of altitude and eosinophil with one-year all-cause mortality. Restricted cubic spline (RCS) was used to investigate the relationship between variables and outcome. In addition, a post hoc analysis was conducted to explore the relationship between EOS and one-year mortality of AECOPD patients at high altitude.

RESULTS

Patients at high altitude had a higher one-year all-cause mortality compared with patients at low altitude (P = 0.001). Multivariate COX regression showed that altitude (HR 3.03, 95% CI 1.22-7.54, P = 0.017), age (HR 2.77, 95% CI 1.31-5.88, P = 0.008) and CRP (HR 2.62, 95% CI 1.29-5.29, P = 0.007) increased the mortality risk in AECOPD patients. BMI (HR 0.34, 95% CI 0.15-0.78, P = 0.011) and EOS (HR 0.16, 95% CI 0.04-0.68, P = 0.013) decreased the mortality risk in AECOPD patients. Age, BMI, EOS and CRP were linearly correlated with one-year mortality of AECOPD. A post hoc analysis revealed that EOS (HR 0.17, 95% CI 0.04-0.70, P = 0.014) decreased the mortality risk in AECOPD patients at high altitude.

CONCLUSION

Patients with COPD at high altitude had a higher one-year mortality. Altitude and EOS are associated with one-year mortality in COPD patients, which underscores the potential therapeutic benefits of EOS in mitigating the mortality risk of AECOPD patients at high altitude.