The diagnostic accuracy of saliva in detecting novel coronavirus in symptomatic or asymptomatic people at risk of COVID-19 exposure: A systematic review and meta-analysis of diagnostic test accuracy (DTA) studies.
Objectives: The present systematic review aimed to evaluate the diagnostic accuracy of saliva in detecting novel coronavirus in symptomatic or asymptomatic people at risk of exposure to COVID-19. Materials and methods: The comprehensive searches were made using four electronic databases [MEDLINE (via PubMed), EMBASE, Google Scholar, and The Cochrane Central Register of Controlled Trials] till 31st April 2020 and clinical trials meeting the predefined inclusion criteria were included. The Real-time polymerase chain reaction (RT-PCR) test analyzing the salivary samples was considered as an index test and analyzing the nasopharyngeal/Oropharyngeal/nasal/throat swabs was considered as a reference standard test. The diagnostic accuracy was measured using sensitivity and specificity, positive and negative likelihood ratios, diagnostic odds ratio, and summary receiver operating curves (SROC). The risk of bias was analyzed using the revised tool for the quality assessment of diagnostic accuracy studies (QUADAS -2). The random effect models were used to pool sensitivity and specificity and the extracted data were analyzed and interpreted using MetaDisc software. Results: From the initial search of 160 studies, 10 studies were included for qualitative analysis, and 4 studies were included for quantitative analysis. The salivary diagnostic showed good sensitivity [0.89 (95% CI: 0.81-0.95; p=0.000; I2 = 92.5%)] and specificity [0.95 (95% CI: 0.92-0.98; p=0.000; I2 = 94.7%)] with “High” quality evidence. The area under the SROC curve was 0.97, inferring an ‘excellent’ diagnostic potential of saliva in detecting COVID-19 patients. Conclusion: The accuracy of salivary samples in detecting the 2019-nCoV in symptomatic and asymptomatic people at risk of COVID-19 exposure indicates a high sensitivity (0.89) and high specificity (0.95) with 'high' certainty of evidence.