<i>A Comparative Study of SAR-CoV-2 Detection using RT-PCR based Testing from a Nasopharyngeal swab versus indwelling tracheostomy in Patients With a TracheostomyComparative Study of SAR-CoV-2 Detection using RT-PCR based Testing from a Nasopharyngeal swab versus indwelling tracheostomy in Patients With a Tracheostomy</i> data

BACKGROUND Nasopharyngeal swab RT-PCR is the standard procedure for COVID-19 testing. In patients with a tracheostomy with an altered airway that bypasses the nasopharynx, the yield of samples from different sites are unknown.METHODS This study is a prospective cross-sectional study. The nasopharyngeal swabs and tracheal secretion samples were collected from 100 patients with a non-plugging tracheostomy tube at Thammasat University Hospital, Pathum Thani, Thailand. The participants were aged between 1-96 years old for screening purposes during the height of the pandemic. The detection result and cycle threshold (Ct) value from each site were analyzed using McNemar’s test with a 95% confidence interval. RESULTS Four participants had positive results. One patient tested positive only for the nasopharyngeal swab, while the other tested positive only for the tracheal secretion sample. No statistically significant difference was found among the discordant and concordant groups (p = 1).DISCUSSION Nasopharyngeal swab RT-PCR is the gold standard in diagnosing COVID-19. The accuracy of screening is therefore instrumental in disease control; however, in patients with a tracheostomy whose altered airway bypasses the nasopharynx, the yield of samples from this has yet to be elucidated. We found two discordant results among four positive cases from 100 patients. One patient tested positive only from the nasopharyngeal swab, while the other tested positive only from the tracheal sample. The percent of agreement was 98, and the Kappa coefficient value was 65.64% (p-value <0.001). According to these results, one sample from the nasopharynx or tracheal tube should be sufficient to determine the infection status in low-risk patients. Meanwhile, for highly suspicious cases, multiple-site sampling should be utilized. CONCLUSIONThis study showed discordance of COVID-19 RT-PCR screening results using sampling from nasopharyngeal swabs and tracheal secretions in tracheotomized patients. Multiple-site sample is suggested in highly suspicious patients with a tracheostomy