Background/Aims: Although a majority of coronavirus disease (COVID-19) cases were characterized as mild, data assessing the development of pneumonia in mild COVID-19 patients are limited. We aimed to examine the effect of pneumonia development on the clinical course of mild COVID-19 in hospitalized patients. Methods: A retrospective cohort study was conducted via medical record review between February 25, 2020 and April 11, 2020 at a single center. The impact of pneumonia development on the time to viral clearance in mild COVID-19 patients was evaluated. Risk factors associated with the development of pneumonia were also identified. Results: Chest radiographs revealed the development of pneumonia in 26.8% of mild COVID-19 patients. The time to pneumonia development was a median of 8.0 days from the onset of symptoms and 3.5 days after hospital admission. A multivariate analysis for predicting pneumonia development identified age ≥65 years (odds ratio [OR]=3.15, 95% confidence interval [CI]=1.14-8.73), cough (OR=2.18, 95% CI=1.29-3.68), dyspnea (OR=3.58, 95% CI=1.10-11.69), and diarrhea (OR=2.69, 95% CI=1.51-4.78) as significant variables. The time to negative conversion was longer in mild COVID-19 patients who developed pneumonia (23.6 days vs. 18.4 days, p=0.003). In Kaplan-Meier estimation and multivariate Cox regression analyses, newly developed pneumonia was significantly related with delayed time to negative conversion (log-rank test, p=0.02; hazard ratio [HR]=2.90; 95% CI=1.06-7.97).

Background Despite the proven benefits of dexamethasone in hospitalized coronavirus disease 2019 (COVID-19) patients, the optimum time for the administration of dexamethasone is unknown. We investigated the progression of COVID-19 pneumonia based on the timing of dexamethasone administration. Methods A single-center, retrospective cohort study based on medical record reviews was conducted between June 10 and September 21, 2020. We compared the risk of severe COVID-19, defined as the use of a high-flow nasal cannula or a mechanical ventilator, between groups that received dexamethasone either within 24 hours of hypoxemia (early dexamethasone group) or 24 hours after hypoxemia (late dexamethasone group). Hypoxemia was defined as room-air SpO 2 <90%. Results Among 59 patients treated with dexamethasone for COVID-19 pneumonia, 30 were in the early dexamethasone group and 29 were in the late dexamethasone group. There was no significant difference in baseline characteristics, the time interval from symptom onset to diagnosis or hospitalization, or the use of antiviral or antibacterial agents between the two groups. The early dexamethasone group showed a significantly lower rate of severe COVID-19 compared to the control group (75.9% vs. 40.0%, p=0.012). Further, the early dexamethasone group showed a significantly shorter total duration of oxygen supplementation (10.45 days vs. 21.61 days, p=0.003) and length of stay in the hospital (19.76 days vs. 27.21 days, p=0.013). However, extracorporeal membrane oxygenation and in-hospital mortality rates were not significantly different between the two groups. Conclusion Early administration of dexamethasone may prevent the progression of COVID-19 to a severe disease, without increased mortality.