Published: 07 August, 2020 | Volume 4 - Issue 1 | Pages: 006-010
Introduction: The disease outbreak of COVID-19 has had a great clinical and microbiological impact in the last few months. In the preanalytical phase, the collection a sample from of a respiratory tract at the adequate moment and from the correct anatomical site is essential for a rapid and precise molecular diagnosis with a false negative rate of less than 20%.
Materials and methods: We conducted a descriptive study of COVID-19 disease with a persistently negative RT-PCR test in patients seen at the National Institute of Respiratory Diseases (INER) in Mexico City in the period of March through May of 2020. 38 patients were registered with negative RT-PCR test obtained through nasopharyngeal and oropharyngeal swabbing. We evaluated the distribution of data with the Shapiro-Wilk test of normality. The non-parametric data are reported with median. The nominal and ordinal variables are presented as percentages.
Results: The average age of our cohort was 46 years and 52.63% were male (n = 20). Diabetes Mellitus was documented in 34.21% (n = 13) of the patients, Systemic Hypertension in 21.05% (n = 8), Obesity in 31.57% (n = 12) and Overweight in 42.10% (n = 16). Exposure to tobacco smoke was reported in 47.36% (n = 18) of the patients. The median initial saturation of oxygen was 87% at room air. The severity of the disease on admission was: mild 71.05% (n = 27), moderate 21.05% (n = 8) and severe or critical in 7.89% (n = 3) of the cases respectively. 63.15% (n = 24) sought medical care after 6 or more days with symptoms. Lymphopenia was documented in 78.94% (n = 30). Median LDH at the time of admission was 300, being elevated in 63.15% (n = 24) of the cases. The initial tomographic imaging of the chest revealed predominantly ground glass pattern in 81.57% (n = 31) and predominantly consolidation in 18.42% (n = 7). The registered mortality was 15.78% (n = 6).
Conclusion: Patients with COVID-19 and a persistently negative RT-PCR test with fatal outcomes did not diﬀer from the rest of the COVID-19 population since they present with the same risk factors shared by the rest of patients like lymphopenia, comorbidities, elevation of D-Dimer and DHL on admission as well as a tomographic COVID-19 score of severe illness, however we could suggest that the percentage of patients with a mild form of the disease is higher in those with a persistently negative RT-PCR test.