Background: In symptomatic patients, the diagnostic approach of Covid-19 should be holistic. We aimed to evaluate the concordance between RT-PCR and serological tests (IgM/IgG), and identify the factors that best predict mortality (clinical stages or viral load). Methods: : The study included 242 patients referred to the University hospital of Kinshasa for suspected Covid-19, dyspnea or ARDS between June 1st, 2020 and August 02, 2020. Both antibody-SARS-CoV2 IgM/IgG and RT-PCR method were performed on the day of admission to hospital. The clinical stages were established according to the Covid-19 WHO classification. The viral load was expressed by the CtN2 (cycle threshold value of the nucleoproteins) and the CtE (envelope) genes of SARS- CoV-2 detected using GeneXpert. Kappa test and Cox regression were used as appropriate. Results: : The GeneXpert was positive in 74 patients (30.6%). Seventy two patients (29.8%) had positive IgM and 34 patients (14.0 %) had positive IgG. The combination of RT-PCR and serological tests made it possible to treat 104 patients as having Covid-19, which represented an increase in cases of around 41% compared to the result based on GeneXpert alone. The comparison between the two tests has shown that 57 patients (23.5 %) had discordant results. The Kappa coefficient was 0.451 (p <0.001). We recorded 23 deaths (22.1 %) among the Covid-19 patients vs 8 deaths (5.8 %) among other patients. The severe-critical clinical stage increased the risk of mortality vs. mild-moderate stage (aHR: 26.8, p < 0.001). The values ​​of CtE and CtN2 did not influence mortality significantly. Conclusion: in symptomatic patients, serological tests are a support which makes it possible to treat a greater number of Covid-19 patients. WHO Clinical classification seems to predict mortality better than SARS-Cov2 viral load.
SARS-CoV2 infection in Symptomatic patients: interest of Serological tests and Predictors of Mortality. Experience of DR Congo