In terms of influential covariates, a number of known risk factors, including age, SpO2, blood pressure, ischaemic and other heart diseases, hypertension, white blood cell count, neutrophils, lymphocytes, high-sensitivity c-reactive protein, creatinine, lactate dehydrogenase, albumin, pH and PCO2, were found to be significantly associated with mortality outcomes in the Optum training fold (Table 2). Here, ALB is linked to hypertensive disorder.