Repeat Molecular Testing for Respiratory Pathogens: Diagnostic Gain or Diminishing Returns?

Abraham J Qavi; Allison McMullen; Carey-Ann D Burnham; Neil W Anderson

doi:10.1093/jalm/jfaa029

Repeat Molecular Testing for Respiratory Pathogens: Diagnostic Gain or Diminishing Returns?

J Appl Lab Med. 2020 Sep 1;5(5):897-907. doi: 10.1093/jalm/jfaa029.

Authors

Abraham J Qavi¹, Allison McMullen¹, Carey-Ann D Burnham¹, Neil W Anderson¹

Affiliation

¹ Department of Pathology & Immunology, Washington University in St. Louis School of Medicine, St. Louis, MO.

Abstract

Background: Upper respiratory tract infections are common, and the ability to accurately and rapidly diagnose the causative pathogen has important implications for patient management.

Methods: We evaluated the test-ordering practices for 2 commonly utilized nucleic acid amplification tests (NAATs) for the detection of respiratory pathogens: the Xpert Flu Assay for influenza A/B (Flu assay) and the Biofire FilmArray respiratory panel assay (RP assay), which detects 20 different targets. Our study examined repeat testing; that is, testing within 7 days from an initial test.

Results: Our study found that repeat testing is common for each of the individual assays: 3.0% of all Flu assays and 10.0% of all RP assays were repeat testing. Of repeat testing, 8/293 (2.7%) of repeat Flu assays and 75/1257 (6.0%) of RP assays resulted diagnostic gains, i.e., new detections. However, for the RP assay, these new detections were not always clinically actionable. The most frequently discrepant organisms were rhinovirus/enterovirus (28/102, 27.5%), followed by respiratory syncytial virus (12/102, 11.8%) and coronavirus OC43 (11/102, 10.8%). Furthermore, there were 3,336 instances in which a patient was tested using both a Flu assay and RP assay, of which only 44 (1.3%) had discrepant influenza results.

Conclusions: Our findings suggest opportunities exist to better guide ordering practices for respiratory pathogen testing, including limiting repeat testing, with the goal of optimization of clinical yield, and diagnostic stewardship.

Keywords: influenza; laboratory utilization; multiplex respiratory pathogen testing.

MeSH terms

Diagnosis, Differential
Humans
Influenza A virus* / genetics
Influenza A virus* / isolation & purification
Influenza B virus* / genetics
Influenza B virus* / isolation & purification
Influenza, Human* / diagnosis
Influenza, Human* / virology
Multiplex Polymerase Chain Reaction / methods
Nucleic Acid Amplification Techniques / methods*
Procedures and Techniques Utilization
RNA Virus Infections* / diagnosis
RNA Virus Infections* / virology
Respiratory Tract Infections* / diagnosis
Respiratory Tract Infections* / virology
Viruses / classification
Viruses / isolation & purification