| Abstract [eng] |
Objectives: To compare the diagnostic value and clinical applicability of SARS-CoV-2 reverse transcription quantitative polymerase chain reaction tests performed on saliva and nasopharyngeal swab samples. Methods: One hundred COVID-19 patients hospitalised at the Infectious Diseases Center of Vilnius University Hospital Santaros Klinikos were included in the study. Three saliva and nasopharyngeal samples were collected every three days in pairs and compared to a control group of 150 healthy individuals. According to the severity of the disease, cases were divided into two groups: mild/moderate (Cohort I, N=47) and severe disease (Cohort II, N=53). Altogether, 592 infectious and 300 non-infectious SARS-CoV-2 reverse transcription quantitative polymerase chain reaction tests from saliva and nasopharyngeal samples were performed. Cohorts were compared by demographic, clinical, laboratory profiles and cycle threshold values of reverse transcription quantitative polymerase chain reaction tests from saliva and nasopharyngeal swab samples. Results: Cycle threshold values of saliva samples were lower than those of nasopharyngeal samples (P=0.002). Despite having significantly lower cycle threshold values in Cohort I compared to Cohort II (P=0.04), the first saliva sample became negative earlier (mean 11.7 days vs 14.8 days, P=0.005). There was a strong positive correlation between the number of days since the onset of symptoms and cycle threshold values in both saliva and nasopharyngeal samples (P<0.001). Saliva samples with a cycle threshold ≤30 were identified as an independent predictor for severe COVID-19 by the multivariate Cox proportional hazards regression analysis (HR=10.06, 95% CI: 1.84-55.14, P=0.008). Conclusion: Salivary testing using reverse transcription quantitative polymerase chain reaction is suitable for detecting early SARS-CoV-2 cases. Additionally, a cycle threshold value ≤ 30 can predict the severity of COVID-19 disease. |
