No tested biomarkers successfully identified postacute sequelae of SARS-CoV-2
The RECOVER study compared 25 biomarkers in patients who had no lingering symptoms of COVID-19 and those who had at least 12 postacute sequelae symptoms and found no significant differences between the groups.
Researchers studied 25 routine labs and found that none were effective as a biomarker for postacute sequelae of SARS-CoV-2 infection (PASC).
This analysis of the NIH's RECOVER-Adult study cohort included 8,746 patients with prior SARS-CoV-2 infection and 1,348 who had not been infected. All had laboratory measures taken at least six months after an index outpatient visit, and patients were excluded if the six-month visit occurred within 30 days of re-infection with COVID-19. PASC was defined based on the presence of 12 symptoms. Participants who had a history of COVID-19 and a PASC index of 12 (n=1,880) were compared to those with a past infection and a PASC index of zero (n=3,351). Results were published by Annals of Internal Medicine on Aug. 13.
Researchers did find some differences between patients with and without prior SARS-CoV-2 infection, with the former having lower mean platelet count (265.9 vs. 275.2 x 109 cells/L) and higher mean HbA1c level (5.58% vs. 5.46%) and urinary albumin-creatinine ratio (81.9 mg/g vs. 43.0 mg/g), but these differences were of modest clinical significance, and the difference in HbA1c levels was attenuated after participants with pre-existing diabetes were excluded. In the comparison of those with previous infections, there were no significant differences associated with a PASC index of 12 or higher versus zero.
The results indicate that “although clinicians should rule out treatable causes of PASC symptoms with appropriate diagnostic testing, routine laboratory tests are not useful biomarkers for PASC,” the study authors said. “Understanding the basic biological underpinnings of persistent symptoms after SARS-CoV-2 infection will likely require a rigorous focus on investigations beyond routine clinical laboratory studies (for example, transcriptomics, proteomics, metabolomics) to identify novel biomarkers.”
An accompanying editorial agreed that the findings suggest clinicians should use testing in PASC only to rule out alternative diagnoses. “We must remember long COVID in our differential diagnoses for symptoms or conditions with no apparent cause. Importantly, acknowledging symptoms with empathy and creating a symptom management plan provides a basis for trust and hope amidst uncertainty,” the editorialists wrote.