Temporal variations in the diagnostic performance of chest CT for Covid-19 depending on disease prevalence: Experience from North-Eastern France.

RATIONALE AND OBJECTIVE: The purpose of this work was to analyze temporal variations in the diagnostic performance of chest CT for Covid-19 throughout the first wave, depending on disease prevalence variations between the ascending, peak and descending phases of the epidemic in North-Eastern France. MATERIALS AND METHODS: From March 6th to April 22nd 2020, all consecutive adult patients referred to the "Covid-19 clinic" of our Emergency Department with the availability of chest CT and of at least one RT-PCR result were retrospectively included in the present study. Chest CT was considered positive when typical Covid-19 lesions were observed (bilateral and predominantly peripheral and sub-pleural ground glass opacities and/or alveolar consolidations). RT-PCR results were considered as the reference standard. Ascending, peak and descending phases were determined based on the number of CT scans performed daily. CT diagnostic performance were calculated and variations between phases were tested for equivalence or difference using Bayesian methods. RESULTS: 2194 consecutive chest CT were analyzed. Overall CT diagnostic performance was Se = 84.2 [82.0 ; 86.3], Sp = 86.6 [84.5 ; 88.5], PPV = 86.1 [84.0 ; 88.1], NPV = 84.7 [82.6 ; 86.7] and accuracy = 85.4 [83.9 ; 86.8], with no significant differences between chest and non-chest radiologists. Variations between the ascending (11 days, 281 chest CT, disease prevalence 37.0 %), the peak (18 days, 1167 chest CT, disease prevalence 64 %) and the descending phases (19 days, 746 chest CT, disease prevalence 32.2 %) were highest for PPV and NPV with a probability of difference >99.9 %, and smallest for accuracy and specificity with a probability of equivalence >98.8 %. CONCLUSION: In a homogenous cohort of 2194 consecutive chest CT performed over a 7-week epidemic wave, we observed significant variations of CT predictive values whereas CT specificity appeared marginally affected.

Patients with Initial Negative RT-PCR and Typical Imaging of COVID-19: Clinical Implications.

The sensitivity of reverse transcriptase polymerase chain reaction (RT-PCR) has been questioned due to negative results in some patients who were strongly suspected of having coronavirus disease 2019 (COVID-19). The aim of our study was to analyze the prognosis of infected patients with initial negative RT-PCR in the emergency department (ED) during the COVID-19 outbreak. This study included two cohorts of adult inpatients admitted into the ED. All patients who were suspected to be infected with SARS-CoV-2 and who underwent a typical chest CT imaging were included. Thus, we studied two distinct cohorts: patients with positive RT-PCR (PCR+) and those with negative initial RT-PCR (PCR-). The data were analyzed using Bayesian methods. We included 66 patients in the PCR- group and 198 in the PCR+ group. The baseline characteristics did not differ except in terms of a proportion of lower chronic respiratory disease in the PCR- group. We noted a less severe clinical presentation in the PCR- group (lower respiratory rate, lower oxygen need and mechanical ventilation requirement). Hospital mortality (9.1% vs. 9.6%) did not differ between the two groups. Despite an initially less serious clinical presentation, the mortality of patients infected by SARS-CoV-2 with a negative RT-PCR did not differ from those with positive RT-PCR.

[French national emergency department's crisis: The outcome of a growing gap between health resources and needs?] / Crise nationale des urgences : le résultat d'un déséquilibre croissant entre offre et demande de soins ?

Overcrowding in Emergency Departments is often considered as an outcome of insufficient access to hospital beds or primary care, therefore a potential lack of health resources. We sought to describe the quantitative evolution of health resources in the French health care system, in comparison with demographic and epidemiologic parameters that reflect health needs. Overall, in the last decade, parameters of capacity and human resources stagnated while activity and spending increased jointly, stimulated by ageing of the population and chronic diseases mostly. Nevertheless, recent official previsions have again recommended to proceed with hospital bed reduction until 2030. This has led to a dangerous saturation of emergency care and to the ongoing systemic health crisis. This situation will require ambitious health resources reinforcement plans in both hospital and primary care. Furthermore, ageing of the population and chronic diseases must lead society to deliberate on the fundamental goals and funding of our health care system.