Predictive factors of COVID-19 in patients with negative RT-qPCR

Objective: To evaluate the factors associated with false negatives in RT-qPCR in patients with mild-moderate symptoms of COVID-19. Materials and methods: This was a cross-sectional study that used a random sample of non-hospitalized patients from the primary care management division of the Healthcare Area of Leon (58 RT-qPCR-positive cases and 52 RT-qPCR-negative cases). Information regarding symptoms was collected and all patients were simultaneously tested using two rapid diagnostic tests - RDTs (Combined - cRDT and Differentiated - dRDT). The association between symptoms and SARS-CoV-2 infection was evaluated by non-conditional logistic regression, with estimation of Odds Ratio. Results: A total of 110 subjects were studied, 52% of whom were women (mean age: 48.2 +/- 11.0 years). There were 42.3% of negative RT-qPCRs that were positive in some RDTs. Fever over 38 degrees C (present in 35.5% of cases) and anosmia (present in 41.8%) were the symptoms most associated with SARS-CoV-2 infection, a relationship that remained statistically significant in patients with negative RT-qPCR and some positive RDT (aOR = 6.64; 95%CI = 1.33-33.13 and aOR = 19.38; 95% CI = 3.69-101.89, respectively). Conclusions: RT-qPCR is the technique of choice in the diagnosis of SARS-CoV-2 infection, but it is not exempt from false negatives. Our results show that patients who present mild or moderate symptoms with negative RT-qPCR, but with fever and/or anosmia, should be considered as suspicious cases and should be evaluated with other diagnostic methods. (c) 2020 Sociedad Espanola de Medicos de Atencion Primaria (SEMERGEN). Published by Elsevier Espana, S.L.U. All rights reserved.