[Potential usefulness of CT as a marker of persistence of positive PCR in patients with COVID-19]

Objective: One of the problems associated to SARS-CoV-2 was its persistence in nasopharyngeal tract. The existence of markers that help to predict this situation could be useful to management of the patients. The objective of this paper was to determine the relationship between the CT value from the initial PCR of patients with COVID-19 and the persistence of the infection.
Methods: It was performed an observational retrospective study of patients with positive PCR to SARS-CoV-2 attended in emergency department of a general hospital. Data about compatible symptoms, radiological findings and the CT value obtained with each PCR kit were collected. The control group (G0) included patients with a positive PCR followed by two negative PCR results (P-N-N), while problem group (G1) included patients with at least three consecutive positive PCR results (P-P-P). Chronic infections were discarded selecting only patients with negative serology, and only were included those whose PCR were separated by a minimum of five and maximum of twenty days. The comparison between the study groups was carried out using the t-student test for quantitative variables and the χ^{2} test for qualitative variables.
Results: The mean CT value were 30.8 and 21.5 (p<0.001) on G0 and G1, respectively. G0 reported higher CT values than G1, regardless of symptoms, radiological pattern and the PCR kit utilized.
Conclusions: The CT value from the SARS-CoV-2 initial PCR is related to the persistence of its positivity, regardless of the patient´s symptoms or radiological pattern. Thus, low CT values could be related to persistent infections.