ABSTRACT
Background: Reverse transcriptase-polymerase chain reaction (RT PCR) testing is an important tool for the diagnosis of coronavirus disease 2019 (COVID19). However, performance concerns have recently emerged, especially about its sensitivity.. We hypothesized that clinical, biological and radiological characteristics of patients with false negative first RT-PCR testing, despite final diagnosis of COVID19, might differ from patients with positive first RT PCR. Methods: Case / control, multicenter study in which COVID19 patients with negative first RT PCR testing were matched to patients with positive first RT PCR on age, gender and initial admission unit (ward or intensive care). Results: Between March 30, and June 22, 2020, 80 cases and 80 controls were included. Neither proportion of death at hospital discharge, nor duration of hospital length stay differed between case and control patients (P=0.80 and P=0.54, respectively). In multivariate analysis, headache (adjusted OR: 0.07 [0.01 ; 0.49]; P=0.007) and fatigue/malaise (aOR: 0.16 [0.03 ; 0.81]; P=0.027) were associated with lower risk of false negative, whereas platelets > 207.103.mm-3 (aOR: 3.81 [1.10 ; 13.16]; P=0.034) and CRP > 79.8 mg.L-1 (aOR: 4.00 [1.21 ; 13.19]; P=0.023) were associated with higher risk of false negative. Interpretation: Patients with suspected COVID19 and higher inflammatory biological signs expected higher risk of false negative RT PCR testing. Strategy of serial RT PCR testings must be rigorously evaluated before adoption by clinicians.
ABSTRACT
Rationale and ObjectivesStudies suggest an association between chest CT findings assessed with semi-quantitative CT score and gravity of Covid-19. The objective of this work is to analyze potential correlation between visual quantification of lesion severity at initial chest CT and clinical outcome in confirmed Covid-19 patients. Materials and MethodsFrom March 5th to March 21st, 2020, all consecutive patients that underwent chest CT for clinical suspicion of Covid-19 at a single tertiary center were retrospectively evaluated for inclusion. Patients with lung parenchyma lesions compatible with Covid-19 and positive RT-PCR were included. Global extensiveness of abnormal lung parenchyma was visually estimated and classified independently by 2 readers, following the European Society of Thoracic Imaging Guidelines. Death and/or mechanical ventilation within 30 days following the initial chest CT was chosen as the primary hard endpoint. Results216 patients (124 men, 62 years-old {+/-} 16.5, range 22 - 94 yo) corresponding to 216 chest CT were included. Correlation between lesion severity and percentage of patients that met the primary endpoint was high, with a coefficient {rho} of 0.87 (p = 0.05). A greater than 25% involvement was significantly associated with a higher risk of mechanical ventilation or death at 30 days, with a Risk Ratio of 5.00 (95% CI [3.59-6.99]). ConclusionThis retrospective cohort confirms a correlation between visual evaluation of lesions severity at initial chest CT and the 30 days clinical outcome of Covid-19 patients and suggests using a threshold of greater than 25% involvement to identify patients at risk.
