Saliva as a diagnostic specimen for testing respiratory virus by a point-of-care molecular assay: a diagnostic validity study

Clin Microbiol Infect. 2019 Mar;25(3):372-378. doi: 10.1016/j.cmi.2018.06.009. Epub 2018 Jun 12.


Objectives: Automated point-of-care molecular assays have greatly shortened the turnaround time of respiratory virus testing. One of the major bottlenecks now lies at the specimen collection step, especially in a busy clinical setting. Saliva is a convenient specimen type that can be provided easily by adult patients. This study assessed the diagnostic validity, specimen collection time and cost associated with the use of saliva.

Methods: This was a prospective diagnostic validity study comparing the detection rate of respiratory viruses between saliva and nasopharyngeal aspirate (NPA) among adult hospitalized patients using Xpert® Xpress Flu/RSV. The cost and time associated with the collection of saliva and nasopharyngeal specimens were also estimated.

Results: Between July and October 2017, 214 patients were recruited. The overall agreement between saliva and NPA was 93.3% (196/210, κ 0.851, 95% CI 0.776-0.926). There was no significant difference in the detection rate of respiratory viruses between saliva and NPA (32.9% (69/210) versus 35.7% (75/210); p 0.146). The overall sensitivity and specificity were 90.8% (81.9%-96.2%) and 100% (97.3%-100%), respectively, for saliva, and were 96.1% (88.9%-99.2%) and 98.5% (94.7%-99.8%), respectively, for NPA. The time and cost associated with the collection of saliva were 2.26-fold and 2.59-fold lower, respectively, than those of NPA.

Conclusions: Saliva specimens have high sensitivity and specificity in the detection of respiratory viruses by an automated multiplex Clinical Laboratory Improvement Amendments-waived point-of-care molecular assay when compared with those of NPA. The use of saliva also reduces the time and cost associated with specimen collection.

Keywords: Automated; Cost; Influenza virus; Nasopharyngeal; Point-of-care testing; Respiratory syncytial virus; Saliva.

Publication types

  • Comparative Study
  • Validation Study

MeSH terms

  • Aged
  • Aged, 80 and over
  • Costs and Cost Analysis
  • Female
  • Humans
  • Influenza A virus / isolation & purification
  • Influenza B virus / isolation & purification
  • Male
  • Middle Aged
  • Molecular Diagnostic Techniques / methods*
  • Molecular Diagnostic Techniques / standards
  • Nasopharynx / virology
  • Point-of-Care Testing*
  • Prospective Studies
  • Reproducibility of Results
  • Respiratory Syncytial Viruses / isolation & purification
  • Respiratory Tract Infections / diagnosis*
  • Respiratory Tract Infections / virology
  • Saliva / virology
  • Sensitivity and Specificity
  • Specimen Handling / economics
  • Specimen Handling / methods*
  • Time Factors