Predictors of characteristics associated with negative SARS-CoV-2 PCR test despite proven disease and association with treatment and outcomes. The COVID-19 RT-PCR Study.

Background: Since December 2019, Coronavirus 2019 (Covid-19) emerged in Wuhan city in China, and rapidly spread throughout China, Asia and worldwide. Recently, concerns emerged about specificity of PCR testing especially sensibility. We hypothesis first that clinical and/or biological and/or radiological characteristics of patients with first false negative COVID19 RT-PCR test despite final diagnosis of COVID-19 are different from patients with first positive COVID19 RT-PCR test. Methods: Case / control study in which patients with first negative COVID19 RT-PCR test were matched to patients with first positive COVID-19 RT-PCR test on age, gender and ward/ICU location at time of RT-PCR test. Results: Between March 30, and June 22, 2020, 82 cases and 80 controls were included. Neither proportion of death at hospital discharge, nor duration of hospital length stay differed between patients Cases and Controls (respectively P=0.53 and P=0.79). In multivariable analysis, fatigue and/or malaise (aOR: 0.16 [0.03 ; 0.81]; P=0.0266), headache (aOR: 0.07 [0.01 ; 0.49]; P=0.0066) were associated with lower risk of false negative whereas platelets upper than 207 per 10.3.mm-3 (aOR: 3.81 [1.10 ; 13.16]; P=0.0344), and CRP>79.8 mg.L-1 (aOR: 4.00 [1.21 ; 13.19]; P=0.0226) were associated with higher risk of false negative. Interpretation: Patients suspected of COVID19 with higher inflammatory biological findings expected higher risk of false negative COVID19 RT-PCR test. Strategy of serial RT-PCR test must be rigorously evaluated before adoption by clinicians.