The Association Between Alveolar–Arterial Oxygen Tension Difference and the Severity of COVID-19 in Patients

Introduction Coronavirus disease 2019 (COVID-19) emerged as a global pandemic and resulted in a significantly high death toll. Therefore, there is an urgent need to find a potential biomarker related to the disease severity that can facilitate early-stage intervention. Methods In the present study, we collected 242 laboratory-confirmed COVID-19-infected patients. The patients were grouped according to the alveolar to arterial oxygen tension difference (P A-a O 2 ) value of COVID-19 infection after admission. Results Among the 242 laboratory-confirmed COVID-19- infected patients, 155 (64.05%) had an abnormal P A-a O 2 value on admission. Compared with the normal P A-a O 2 group, the median age of the abnormal P A-a O 2 group was significantly older ( p = 0.032). Symptoms such as fever, cough, and shortness of breath were more obvious in the abnormal P A-a O 2 group. The proportion of severe events in the abnormal P A-a O 2 group was higher than the normal P A-a O 2 group (10.34% vs. 23.23%, p = 0.013). The abnormal P A-a O 2 group had a higher possibility of developing severe events compared with the normal P A-a O 2 group (HR 2.622, 95% CI 1.197–5.744, p = 0.016). After adjusting for age and common comorbidities (hypertension and cardiovascular disease), the abnormal P A-a O 2 group still exhibited significantly elevated risks of developing severe events than the normal P A-a O 2 group (HR 2.986, 95% CI 1.220–7.309, p = 0.017). Additionally, the abnormal P A-a O 2 group had more serious inflammation/coagulopathy/fibrinolysis parameters than the normal P A-a O 2 group. Conclusion Abnormal P A-a O 2 value was found to be common in COVID-19 patients, was strongly related to severe event development, and could be a potential biomarker for the prognosis of COVID-19 patients.