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

  1. J. López de la Iglesia 1
  2. T. Fernández-Villa 2
  3. A. Rivero 3
  4. A. Carvajal 4
  5. E. Bay Simon 5
  6. M. Martínez Martínez 6
  7. H. Argüello 4
  8. H. Puente 4
  9. J.P. Fernández Vázquez 7
  1. 1 Centro de salud Condesa, León, Spain
  2. 2 Grupo de Investigación en Interacciones Gen-Ambiente y Salud (GIIGAS)/Instituto de Biomedicina (IBIOMED), Universidad de León, León, Spain
  3. 3 Gerencia de Atención Primaria del Área de Salud de León, Spain
  4. 4 Departamento de Sanidad Animal, Universidad de León, León, Spain
  5. 5 Centro de Salud San Andrés del Rabanedo, León, Spain
  6. 6 Gerencia de Atención Primaria, León, Spain
  7. 7 Gerencia de Atención Primaria de León, León, Spain
Semergen: revista española de medicina de familia

ISSN: 1138-3593

Year of publication: 2020

Issue Title: COVID19 en Atención Primaria

Issue: 1

Pages: 6-11

Type: Article


More publications in: Semergen: revista española de medicina de familia

Sustainable development goals


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 °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.

Funding information

The authors would like to thank all patients for their participation in this study who have voluntarily agreed to collaborate in the evaluation of diagnostic techniques against COVID-19. Thank you to the primary care management division of the Healthcare Area of Leon and the University of Leon also, because their collaboration has been crucial in developing this study.


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