Respiratory involvement parameters in hospitalized COVID-19 patients and their association with mortality and length of stay

Introduction/Background Patients with Coronavirus Disease 2019 (COVID-19) present with a spectrum of respiratory symptoms. There are no studies describing respiratory system involvement adjusted for other organ systems, oxygen saturation nadir, hospitalization days until respiratory involvement, proportion of days of respiratory system involvement, and persistent respiratory involvement at discharge in COVID-19 patients. We studied these parameters in COVID-19 patients that received respiratory therapy interventions and their association with mortality and length of stay (LOS). Methods A single-center cross-sectional retrospective study of 738 COVID-19 patients with respiratory involvement at a hospital in the New York metropolitan area. Results COVID-19 patients with respiratory involvement had increased mortality with oxygen requirement of FiO2 >55% (OR:39.02, 95% CI:1.59–960.51, P < 0.05) and mechanical ventilation (OR:236.64, 95% CI:8.24–6798.93, P < 0.01). Respiratory system involvement adjusted for other organ system involvement was associated with increased mortality (OR:1.60, 95% CI:1.20, 2.14, P < 0.01) and LOS (B = 0.02, SE = 0.01, P < 0.01). Oxygen saturation nadir of 70%–89% was significantly associated with increased LOS (B = 0.07, SE = 0.03, P < 0.05), whereas oxygen saturation nadir of <70% was associated with increased mortality (OR:12.95, 95% CI:2.72–61.61, P < 0.01). An increased proportion of days in hospital with respiratory system involvement was associated with decreased mortality (OR:0.004, 95% CI:<0.001–0.06, P < 0.001) and increased LOS (B = 0.90, SE = 0.07, P < 0.001). Respiratory involvement on days 4–7 was associated with decreased mortality (OR:0.02, 95% CI:<0.003–0.17, P < 0.001), and respiratory involvement on day >1 was associated with increased LOS. Respiratory involvement persistent at discharge was associated with increased mortality (OR:56.82, 95%CI:18.51–174.43, P < 0.001). Conclusions Among all respiratory parameters, high oxygen requirements and low oxygen saturation nadir are the most predictive of COVID-19 prognosis.