Association between cycle threshold (C_t ) values and clinical and laboratory data in inpatients with COVID-19 and...

In-house assays for the diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by quantitative reverse-transcription polymerase chain reaction (qRT-PCR), are feasible alternatives, particularly in developing countries. Cycle threshold (C_t ) values obtained by qRT-PCR were compared with clinical and laboratory data from saliva of inpatients with COVID-19 and asymptomatic health workers (AHW) were studied. Saliva specimens from 58 inpatients confirmed by qRT-PCR for SARS-CoV-2 using nasopharyngeal specimens, and 105 AHW were studied by qRT-PCR using three sets of primers for the N (N1, N2, and N3) gene of SARS-CoV-2, according to the CDC Diagnostic Panel protocol, showing a positivity of 88% for inpatients and 8% for AHW. Bivariate analysis revealed an association between C_t  < 38.0 values for N2 and mechanical ventilation assistance among patients (p = .013). In addition, values of aspartate-transaminase, lactate dehydrogenase, and ferritin showed significant correlations with C_t values of N1 and N3 genes in inpatients. Therefore, our results show that C_t values correlate with some relevant clinical data for inpatients with COVID-19.