Note on the recent NIH Long COVID study

Jun 1, 2022

On May 24th, Annals of Internal Medicine published a widely debated study on Post-Acute Sequelae of COVID-19 (PASC).  This study, sponsored by the RECOVER COVID Initiative, enrolled 189 people with lab-confirmed COVID and compared them with 120 controls, people never infected with COVID.  This study demonstrated that persistent symptoms after COVID were common, but that abnormal findings on physical examination or diagnostic testing were uncommon.  Another key finding of this study was that women and those with a history of anxiety were at increased risk for PASC. However, these headlines do not tell the whole story and, in fact, may serve to frustrate many Long COVID patients.

While more research is needed to understand PASC / Long COVID, the conclusions of this most recent study has the potential to propagate the stigma experienced by patients with Long COVID. It is important to note that this study is challenged by critical methodological flaws, particularly in the way that participants were recruited through advertisements. When there is something different about the people who volunteer through advertising versus the rest of the population, selection bias can be introduced into a study. It is possible, and perhaps likely, a person with a history of anxiety might be more apt to volunteer for a study about Long COVID if they suspect that they indeed have Long COVID. This type of “selection bias” can lead us to falsely assume what we observe in a study sample also holds true for the population at large. Since we still know relatively little about Long COVID, small studies like this can impact the narrative, but it might not always be in a good way. However, this study did contribute useful information about diagnostic testing in Long COVID by demonstrating that conventional testing (e.g., common blood tests) is unlikely to help distinguish Long COVID from other conditions.

While a lack of diagnostic testing may continue to frustrate patients and clinicians, it is important that diagnostic testing is rigorously evaluated. Unfortunately, this means that we still need to keep looking for the best means to diagnose and treat Long COVID and remember that one study alone is unlikely to change to practice. 

From the Long COVID Initiative Faculty Director, Dr. Francesca Beaudoin, MD, MS, PhD, Interim Chair of the Department of Epidemiology; Associate Professor of Emergency Medicine and Health Services, Policy and Practice, Brown University School of Public Health

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