Researchers have developed a definition and symptom checklist for long COVID, based on initial findings from a study of nearly 10,000 Americans.
The study identified a set of 12 long-term symptoms that can occur following infection with COVID-19. These symptoms — ranging from "brain fog" to chest pain — are linked to the effects of the coronavirus on multiple organ systems.
Using these symptoms, the research team created a diagnostic checklist for what they call PASC (Postacute Sequelae of SARS-CoV-2) — another term for long COVID.
Symptoms contributing to the new PASC score include: post-exertional malaise; fatigue; brain fog; dizziness; gastrointestinal symptoms; heart palpitations; changes in sexual desire or capacity; affected smell or taste; thirst; chronic cough; chest pain; and abnormal movements.
About 10% of study participants infected during the initial Omicron wave wound up positive for long COVID within six months of their initial illness based on the new PASC definition, the researchers said.
“This study is an important step toward defining long COVID beyond any one individual symptom,” said study co-author Dr. Leora Horwitz, director of the Center for Healthcare Innovation and Delivery Science at NYU Langone Health, in New York City.
“This approach — which may evolve over time — will serve as a foundation for scientific discovery and treatment design,” Horwitz added in a news release from the U.S. National Institutes of Health.
Who's at risk?
Patients were more likely to develop long COVID if they weren't vaccinated, the researchers found.
About 17% of unvaccinated Omicron-wave patients developed long COVID based on their PASC score, compared with 10% of fully vaccinated patients, the results showed.
Long COVID also was more common among people who suffered reinfections. About 20% of reinfected participants developed long COVID compared with 10% of participants with one reported infection.
The study was coordinated through an NIH initiative called Researching COVID to Enhance Recovery, or RECOVER.
The researchers examined data from 9,764 adults, including 8,646 who had COVID-19 and 1,118 who were not infected.
The investigators assessed more than 30 symptoms across multiple body areas and organs, and identified 12 symptoms that most set apart those with and without long COVID.
The researchers then established a scoring system based on patient-reported symptoms, assigning points to each of the 12 symptoms.
With those scores, the team identified a meaningful threshold for identifying participants with long COVID.
They also found that certain symptoms tended to occur together, forming four long COVID subgroups or “clusters”:
The researchers next plan to check the PASC score for accuracy against an array of lab tests and imaging, they said.
Further research is also needed into the underlying biological mechanisms of long COVID, so that scientists can develop effective treatments and prevention strategies, the experts noted.
“While the score developed in this study is an important research tool and early step toward diagnosing and monitoring patients with long COVID, we recognize its limitations,” said Dr. David Goff, director of cardiovascular sciences at the U.S. National Heart, Lung, and Blood Institute. Goff serves as an epidemiology lead for RECOVER.
“All patients suffering from long COVID deserve the attention and respect of the medical field, as well as care and treatment driven by their experiences,” Goff added. “As treatments are developed, it will be important to consider the complete symptom profile.”
The study was published online May 25 in the Journal of the American Medical Association.
The U.S. National Institutes of Health has more about RECOVER.
SOURCE: U.S. National Institutes of Health, news release, May 25, 2023