By Denise Baez
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral load among hospitalised patients is independently associated with the risk of intubation and in-hospital mortality, according to a study published in Clinical Infectious Diseases.
Reed Magleby, MD, NewYork-Presbyterian Hospital, Weill Cornell Medical Center, New York, New York, and colleagues evaluated 678 hospitalised patients with coronavirus disease 2019 (COVID-19) and found that 35% of patients with a high SARS-CoV-2 viral load on admission died, compared with 17.6% of patients with medium viral loads and 6.2% of patients with low viral loads.
The findings suggest that using cycle threshold (Ct) values, which are available when results from reverse transcription-polymerase chain reaction (RT-PCR) assays are reported to clinicians, could identify patients at highest risk of intubation and death and guide treatment accordingly.
“We found that admission SARS-CoV-2 viral loads, as determined by Ct values that are generated with standard-of-care diagnostic assays, are independently associated with intubation and death among hospitalised patients with COVID-19,” the authors wrote. “These findings highlight the critical role of viral load in SARS-CoV-2 pathogenesis and suggest that Ct values should be reported to assist clinicians in identifying patients at high risk for adverse COVID-19-related outcomes.”
Dr. Magleby and colleagues analysed data from 678 patients who were hospitalised with COVID-19 between March 30, 2020, and April 30, 2020 at 2 hospitals in New York City. SARS-CoV-2 viral load was assessed using Ct values from a RT-PCR assay applied to nasopharyngeal swab samples.
In-hospital mortality was 35% among the 220 patients with a high viral load (Ct <25), 17.6% among the 216 with a medium viral load (Ct 25-30), and 6.2% among the 242 patients with a low viral load (Ct>30). The risk of intubation was also higher in patients with a high viral load (29.1%), compared with those with a medium (20.8%) or low viral load (14.9%).
In a multivariate model that adjusted for age, race, coronary artery disease, congestive heart failure, cerebrovascular disease, hypertension, chronic obstructive pulmonary disease, days of symptoms prior to admission, symptoms upon presentation, initial chest x-ray findings, and level of oxygen support within three hours of arrival to the emergency department, having a high viral load was independently associated with increased risk of in-hospital mortality (adjusted odds ratio [aOR] = 6.05; 95% confidence interval [CI], 2.92-12.52; P< 0.001) compared with having a low viral load.
The risk of in-hospital mortality was also higher in patients with a medium viral load compared with a low viral load, but this association was not statistically significant (aOR = 2.06; 95% CI, 0.98-4.34; P = 0.058).
Compared with those with a low viral load, having a high viral load was also independently associated with increased risk of intubation (aOR = 2.73; 95% CI, 1.68-4.44; P < 0.001). The risk of intubation associated with a medium viral load did not reach statistical significance (aOR = 1.59; 95% CI, 0.96-2.63; P = 0.07).
Higher viral load was associated with increased age, comorbidities, smoking status, and recent chemotherapy. Patients with higher viral loads were also more likely to develop myocardial infarction, congestive heart failure, and acute kidney injury requiring hemodialysis.
“While prior studies indicated that viral load correlates with severity of COVID-19 presentation, our study of a larger cohort of hospitalised patients adds to this knowledge base by identifying that admission viral load has important prognostic implications,” the authors wrote. “Reporting SARS-CoV-2 viral load based on Ct values from admission NP swab samples could therefore help identify patients who are at highest risk of adverse outcomes and who therefore may benefit from more intensive monitoring. Identifying high viral load patients could also be helpful for allocating scarce therapeutic interventions such as antiviral agents [remdesivir].”
The authors noted that additional studies that evaluate viral loads and clinical outcomes among all patients who present to the emergency department are warranted prior to pursuing this strategy clinically.