Multiplex PCR in Critically Ill Hematology Patients

Written by Clay Smith

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Presence of any virus on multiplex PCR (particularly influenza, parainfluenza, and RSV) in critically ill hematology patients was associated with an increased risk for respiratory failure and ICU mortality.

Why does this matter?
Multiplex PCR virus testing is increasingly common and is both sensitive and specific. It may help determine the etiology of a patients’ symptoms, alter management in cases of influenza, or help determine disposition.

Not “just a virus” in these patients…
This was a post hoc analysis of a prior prospective multicenter study of critically ill hematology patients in which nasal swabs were collected and frozen for later analysis. Of the 747 patients, 447 of which had respiratory failure, 21.3% were positive on virus PCR assay: 56.4% rhinovirus/enterovirus (26% mortality); 30.7% influenza/parainfluenza/RSV (37% mortality). Any virus positivity was statistically significantly associated with respiratory failure (25.5% vs. 16.3%) and mortality (28.9% vs. 19.3%). Odds of death in patients with respiratory failure doubled in those who were PCR-positive for any virus, and the association was even stronger when positive for influenza, parainfluenza, or RSV (viruses known to cause pneumonia). The types of hematology patients most often affected were those with lymphoproliferative disorders, stem cell transplantation, and those on steroids or immunosuppressive medications. Keep in mind, these tests are very sensitive and could have detected some patients with asymptomatic carriage of a virus. And this does not prove causality from viral infection, rather association.

I think this study could change management for both disposition and treatment. I see this as a novel way to risk stratify ill hematology patients. Those positive for any virus need a lower threshold for ICU-level care. Using a multiplex viral panel could also allow for earlier detection and treatment of influenza-positive patients with antiviral agents.

Source
Clinical Significance of Upper Airway Virus Detection in Critically Ill Hematology Patients. Am J Respir Crit Care Med. 2019 Feb 15;199(4):518-528. doi: 10.1164/rccm.201804-0681OC.

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Reviewed by Thomas Davis

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