COVID-19 Evidence Alerts
from McMaster PLUSTM

Current best evidence for clinical care (more info)

Diagnosis Ricco M, Ranzieri S, Peruzzi S, et al. RT-qPCR assays based on saliva rather than on nasopharyngeal swabs are possible but should be interpreted with caution: results from a systematic review and meta-analysis. Acta Biomed. 2020 Sep 7;91(3):e2020025. doi: 10.23750/abm.v91i3.10020.

BACKGROUND AND AIM OF THE WORK: The ongoing pandemic has elicited an increasing interest regarding the SARS-CoV-2 viral RNA detection in saliva specimens rather than through nasopharyngeal swabs. Our aim was to conduct a meta-analysis on the sensitivity and specificity of SARS-CoV-2 viral RNA detection through RT-qPCR based on salivary specimens compared to conventional nasopharyngeal swabs.

METHODS: We reported our meta-analysis according to the PRISMA statement. We searched Pubmed, Embase, and pre-print archive medRxiv.og for eligible studies published up to June 1st, 2020. Raw data included true/false positive and negative tests, and the total number of tests. Sensitivity and specificity data were calculated for every study, and then pooled in a random-effects model. Heterogeneity was assessed using the I2 measure. Reporting bias was assessed by means of funnel plots and regression analysis.

RESULTS: The systematic review eventually retrieved 14 studies including a total of 15 estimates, the were included in quantitative synthesis. We found a pooled specificity of 97.7% (95%CI 93.8-99.2) and a pooled sensitivity of 83.4% (95%CI 73.1-90.4), with an overall agreement assessed by means of Cohen's kappa equals to 0.750, 95%CI 0.62-0.88 (i.e. moderate agreement), with high heterogeneity and risk of reporting bias.

CONCLUSIONS: In conclusion, diagnostic tests based on salivary specimens are somewhat reliable, but relatively few studies have been carried out. Moreover, such studies are characterized by low numbers and low sample power. Therefore, the of salivary samples is currently questionable for clinical purposes and cannot substitute other more conventional RT-qPCR based on nasopharyngeal swabs.

Discipline / Specialty Area Score
Emergency Medicine
Public Health
Hospital Doctor/Hospitalists
Internal Medicine
Infectious Disease
General Internal Medicine-Primary Care(US)
Family Medicine (FM)/General Practice (GP)
Comments from MORE raters

Emergency Medicine rater

As an Internist, I find this information highly relevant to my every day clinical practice.

Hospital Doctor/Hospitalists rater

This is limited by linguistic issues, small sample numbers, and ambiguous conclusions.

Internal Medicine rater

Clinical doctors welcome all reliable studies concerning the rapid diagnostic pathways in Covid-19 disease.

Public Health rater

The relevance of this article is related to the opportune overflow of a new test for Covid-19. The conclusion notes that the saliva PCR test does not match the current nasal swab standard for now, but it is worth knowing about it.