SOFA Score Not Helpful for Ventilator Triage in Patients With COVID-19 Pneumonia

By Reuters Staff

February 25, 2021

NEW YORK (Reuters Health) - The Sequential Organ Failure Assessment (SOFA) score has "inadequate" discriminant accuracy for ventilator triage of patients with COVID-19, clinicians caution.

"Although we all wish for an objective tool that would take bedside clinicians off the hook of deciding on ventilator triage, the objective tools we currently have are incredibly weak in terms of discriminating who will most benefit," Robert A. Raschke of the University of Arizona College of Medicine, in Phoenix, told Reuters Health by email.

"Subjectivity is hard for us to deal with, but it’s always been an important part of bedside medicine, which cannot easily be made to be 'cook-book.' believe that the decisions of bedside clinicians should be relied upon until such time that we have objective tools with reliable discriminant accuracy," said Dr. Raschke.

COVID-19 triage policies often use some form of the SOFA score, the researchers note in JAMA. However, pre-pandemic studies have shown that the SOFA score has only "moderate" discriminant accuracy for predicting survival in intensive-care unit (ICU) patients with sepsis, with area under the receiver operating characteristic curve (AUROC) of 0.74 to 0.75, they point out.

Dr. Raschke and colleagues hypothesized that the SOFA score might be less accurate in COVID-19 patients requiring mechanical ventilation because these patients generally have severe dysfunction in just a single organ and less variation in SOFA scores.

To test their hypothesis, they analyzed data on 675 adults who were treated in 18 ICUs in the United States. The patients all had COVID-19 pneumonia and were receiving oxygen therapy for four hours or more before endotracheal intubation.

The SOFA score assigns zero to four points to each of six organ systems based on the ratio of the partial pressure of oxygen to fraction inspired oxygen, Glasgow Coma Scale score, mean arterial pressure, serum creatinine level, bilirubin level, and platelet count. The SOFA score ranges from zero to 24 points and higher scores indicate worse organ function.

Dr. Raschke's team calculated SOFA scores using the worst values observed within 48 hours before intubation - the point in time when ventilator triage for a patient with COVID-19 pneumonia would theoretically occur, they explain.

The median SOFA score for their cohort of patients was six (interquartile range, four to eight). Respiratory SOFA subscores were three to four in 83.5% of patients.

The other SOFA subscores were zero to one in 72.1% of patients for the renal system, 78.5% for the central nervous system, 94.2% for coagulation, 95.1% for the cardiovascular system, and 96.5% for the hepatobiliary system.

More than half of the patients died or were discharged to hospice (59.3%). The AUROC for the SOFA score was 0.59 compared with 0.66 for age.

"The discriminant accuracy of the SOFA score for mortality prediction in patients prior to intubation for COVID-19 pneumonia was poor and significantly inferior to simply using age," the authors write.

Dr. Raschke told Reuters Health, "Age is perhaps the most important single determinant of outcome in almost all human diseases. Yet, it seemed like somehow political considerations overcame common sense and science when it came to consideration of using age in ventilator triage policies."

As a clinician, he said, he could easily be faced with the choice of using a ventilator for a 36-year-old woman with five young children or an 87 year old man living in a nursing home. "I thank God that we never had to make such a hard choice," he said.

SOURCE: JAMA, online February 17, 2021