Comparison of clinical characteristics between patients with coronavirus disease 2019 (COVID-19) who retested RT-PCR positive versus negative: a retrospective study of data from Nanjing

Background: The epidemiological and clinical characteristics of patients with coronavirus disease 2019 (COVID-19) have been reported. However, the prevalence of retesting positive by RT-PCR for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the associated patient characteristics, remain unclear. Methods: We included 90 confirmed cases of COVID-19 treated in the Nanjing Public Health Center from January 20, 2020 to February 16, 2020 in this retrospective study. All patients completed treatment for COVID-19 and were retested by RT-PCR for SARS-CoV-2 4-20 days after completion of therapy. The clinical characteristics between patients with who retested positive versus negative by RT-PCR were compared, and the factors predictive of positive retesting were analyzed. Positive retesting was modeled with the area under the receiver operating characteristic curve (AUC). Results: The age range of the study population was 0.8-97 years, and all patients were cured or showed improvement. A total of 10 (11%) patients retested positive by RT-PCR 4-20 days after completion of therapy. As compared with patients who retested negative, those who retested positive had a lower percentage of pre-admission fever, a higher percentage of post-admission fever, a lower percentage of bilateral lung infection, higher white blood cell (WBC) count and creatine phosphokinase, and lower hypersensitive c-reactive protein (hs-CRP), interleukin-6 and erythrocyte sedimentation rates (all P<0.05). Logistic regression analysis of the above eight key variables showed that lower hs-CRP and higher WBC were independently associated with positive retesting by RT-PCR. A combination of hs-CRP and WBC were predictive of positive retesting, with an AUC of 0.859. Conclusions: Patients with COVID-19 who retested positive by RT-PCR for SARS-CoV-2 had mild symptoms and better blood testing results. A combination of hs-CRP and WBC may predict positive retesting by RT-PCR; however, the sensitivity and specificity should be studied further.