From March 6, 2020 to May 10, 2020, 20,341 patients were admitted in the participating EDs, 7,199 (35.4%) were hospitalized, 2,789 of whom were suspected of SARS-CoV-2 infection. A total of 103 patients were not included in the study due to missing RT-PCR test. Among the 7,199 admitted patients, 2,686 (37.3%) were tested and 760/2,686 (28.3%) tests were positive. The flow chart is detailed on Figure 1.
Patient characteristics according to the COVID-19 status
The mean ± SD age of COVID-19 positive patient was 71.5 ± 16.5 years, 618 (81.6%) were coming from home and 119 (15.7%) from long-term care facilities. Hypertension was found in 364 (48.0%) COVID-19 positive patients, chronic cardiac disease in 228 (30.0%), diabetes in 186 (24.5%), obesity in 126 (16.6%), and chronic respiratory disease in 114 (15.0%). Oxygen was required upon arrival at the EDs for 179 (23.6%) COVID-19 positive patients, and for 353 (18.3%) COVID-19 negative patients. A total of 215 (30.6%) COVID-19 positive patients went to the EDs more than 7 days after symptom onset (315 (19.0%) COVID-19 negative patients did) and 105 (15.0%) during the first 24 hours after symptom onset (613 (36.9%) COVID-19 negative patients did). Fever was encountered in 536 (70.5%) COVID-19 positive patients, dyspnea in 494 (65.0%), cough in 420 (55.3%), and weakness in 399 (52.5%). Bacterial co-infection was found in 57 (9.3%) COVID-19 positive patients and 221 (14.6%) in COVID-19 negative patients. A total of 454 (59.7%) COVID-19 positive patients had a CT-scan evocative of COVID-19 (Table 1).
Outcomes of patients
The proportion of patients admitted in ICU directly from ED was significantly higher among COVID-19 positive patients (86, 11.3%) compared to COVID-19 negative patients (162, 8.4%; p=0.036), and the risk of ICU admission directly from ED was greater with a positive COVID-19 status (univariate analysis: odd ratio (OR) [95% confidence interval, CI] = 1.34 [1.00; 1.83], p = 0.020; multivariate analysis: OR [95% CI] = 1.34 [1.00; 1.78], p = 0.048). Similarly, the proportion of patients secondarily admitted in ICU was significantly higher among COVID-19 positive patients (99, 14.7%) compared to COVID-19 negative patients (44, 2.5%; p<0.001), and the risk of secondary ICU admission was greater with a positive COVID-19 status (univariate analysis: OR [95% CI] = 6.80 [4.74; 9.91], p <0.001; multivariate analysis: OR [95%CI] = 6.11 [4.20; 9.03], p < 0.001). Overall, 185 (24.3%) COVID-19 positive patients were admitted in ICU, and 206 (10.7%) COVID-19 negative patients were (p<0.001). The use of ventilation support - more specifically, the use of invasive mechanical ventilation and nasal high-flow nasal oxygen therapy - was significantly more frequent among COVID-19 positive patients (89, 11.9% and 135, 18.1%, respectively) compared to COVID-19 negative patients (37, 1.9% and 41, 2.2%, respectively; p< 0.001 for both techniques). The median [IQR] length of stay in hospital was significantly longer for COVID-19 positive patients (10 [6 - 15] days) compared to COVID-19 negative patients (6 [2 - 11] days; p<0.001). Mortality during hospitalization was significantly higher among COVID-19 positive patients (139, 18.3%) compared to COVID-19 negative patients (149, 7.7%; p<0.001), and the mortality risk was greater with a positive COVID-19 status (univariate analysis: OR [95% CI] = 2.67 [2.08; 3.42], p<0.001; multivariate analysis: OR [95% CI] = 3.05 [2.22; 3.99], p<0.001). Similarly, the number of decisions of withholding or withdrawing life-sustaining treatments in EDs and during hospitalization was greater concerning COVID-19 positive patients (53, 7.0% and 151, 19.9%, respectively) than concerning COVID-19 negative patients (90, 4.7% and 221, 11.5%; p=0.001 and p<0.001, respectively). After hospital discharge, a greater proportion of COVID-19 positive patients went into a rehabilitation department before returning home (157, 28.3%) compared to COVID-19 negative patients (245, 15.1%; p<0.001; Table 2).
Patient pathway from the emergency departments
The proportion of patients who died during conventional hospitalization and in ICU was higher among COVID-19 positive patients (92, 13.7% and 46, 24.9%, respectively) compared to COVID-19 negative patients (109, 6.2% and 32, 15.6%; p< 0.001 and p=0.016, respectively). Among the 673 COVID-19 positive patients who were in conventional hospitalization, 53 (7.9%) were discharged early (<48h) from hospital, compared to 408 (23.9%) COVID-19 negative patients. The patient pathway of COVID-19 positive and COVID-19 positive patients is detailed in Figure 2.
Changes in terms of care over the study period among COVID-19 positive patients
The number of COVID-19 positive patients rapidly increased over the course of March, 2020 with a peak number reached on March 27, 2020 (Fig 3). The number of patients admitted to the ICU decreased since the beginning of the study. The death rate was stable over the study period. However, before April 15, 2020 patients requiring ICU and intubation were more likely to die whereas after April 15, 2020 patients who did not go into ICU were more likely to die (Fig 4). The number of decisions of withholding or withdrawing life-sustaining treatments was stable over time. The age of COVID-19 positive patients admitted to EDs was stable during the study period. The age of the deceased COVID-19 positive patients increased during the second period of the study (supplemental material S2 and S3).
Patient outcomes according to age
No COVID-19 positive patients over 90 was concerned by hospitalisation of less than 48 hours, but about 19.2% (39) of COVID-19 negative patients over 90 were. The ICU admission concerned mostly COVID-19 positive patients under 80. The proportion of death was higher in higher-aged groups, this proportion was even higher among COVID-19 positive patients (33.6% of death for patients over 80) compared to COVID-19 negative patients (11.9% of death for patients over 80; p=0.014; Fig 5).