The average person suffering from long covid didn’t have a severe infection to begin with, a new report suggests. The study, an examination of private insurance claims, found that three-fourths of diagnosed long covid patients were not hospitalized for covid-19. Additionally, the researchers found that patients were most likely to be co-diagnosed with symptoms such as fatigue and trouble breathing.
Last October, long covid was codified into the latest edition of the International Classification of Disease (ICD-10), a codebook used by doctors, hospitals, and insurance companies for diagnostic and billing purposes. This code, officially known as “U09.9 Post covid-19 condition, unspecified,” allowed patients to be formally recognized as having long covid. But it also provided another way for researchers to study these patients on a larger scale.
This report, conducted by FAIR Health, a nonprofit company that describes itself as having the country’s largest database of privately billed health insurance claims, is one of the first pieces of research to do just that.
Using their database, the authors identified nearly 80,000 patients who had been diagnosed with post-covid symptoms in the four months after the ICD code was implemented, up through January 2022. Most patients (75.8%), they found, had never been hospitalized for their original covid-19 case.
“Post-covid conditions have become an issue of growing national concern,” said Robin Gelburd, FAIR Health president, in a news release. “We hope these findings prove helpful for all individuals diagnosed with post-covid conditions, as well as for providers, payors, policy makers and researchers.”
Other research has consistently found that the more severe your initial infection, the more likely you are to experience lingering complications and early death. But studies have also shown that even people with mild to moderate cases are at risk for developing a variety of health problems afterward, to a greater extent than people who experience other respiratory infections. Most people who catch covid-19 also don’t end up in the hospital. So while the individual risk of prolonged symptoms may be smallest for people who had milder covid-19, there are simply many more people in that group than there are survivors of severe illness.
The report’s other findings might provide added insight into long covid. The most represented age group of patients (34.6%) were between 36 and 50 years old, for instance, but that might be because older Americans are usually covered through public Medicare plans. Women were more likely to be diagnosed than men and were more likely to not have been hospitalized originally. The three most common conditions to be diagnosed at the same time were “abnormalities of breathing” (23.2%), cough (18.9%), and malaise/fatigue (16.7%). And while many patients did have preexisting health conditions, 30% had been never diagnosed with any chronic illness prior to their long covid.
The report is a white paper, meaning that it hasn’t gone through formal peer review, an important part of validating any scientific research. So the findings should be taken with more caution than usual. No single study, even peer-reviewed, should be the final word on anything. But the sheer amount of data available does lend credibility to the results, and it’s likely that other researchers will be able to use ICD-10 data for similar studies in the future.
For their part, the authors do plan to analyze their data further, both to track the long-term outcomes of these patients and to examine whether vaccination reduced the risk of long covid, as other research has suggested it can.