Nearly a quarter of workers compensation claimants who were treated for COVID-19 experienced persistent symptoms or a relapse months later, according to a new study by the National Council on Compensation Insurance.

The researchers found that workers who were hospitalized for COVID-19 were more likely to suffer “long-COVID” — 47 percent compared to 20 percent of COVID patients who were not hospitalized. Overall, 24 percent of claimants suffered long-haul symptoms within 270 days of receiving acute care.

Claims costs were also much higher for claimants who experienced prolonged symptoms, especially if they were treated at a hospital. The report says treatment for long-COVID patients who were hospitalized cost an average of $216,000 per claim compared to $40,000 for long-COVID claimants who were not hospitalized and $7,000 for claimants who were not hospitalized and did not suffer long-term effects.

Dr. Michael Choo, chief medical officer for Paradigm, worked with NCCI researchers on the report. The team studied 7,651 COVID-19 claims with accident dates from March 1, 2020 through June 30, 2021.

The researchers identified patients as having long-COVID if medical treatment for symptoms of the disease was reported more than 30 days after hospital discharge or the reported accident date but no longer than 270 days after. That effectively gave each claim an eight-month observation window.

NCCI spokeswoman Christine Pike said the 270-day window was chosen so researchers could observe claims over a specific period with the most recently reported medical treatment data available.

The researchers found that females were more likely to report long-COVID, outnumbering males nearly 4-1. However, females also make up greater percentage of the workforce in the healthcare occupations that were most likely to contract the disease.

Long-COVID sufferers reported a variety of symptoms, most of which impacted the pulmonary and cardiovascular systems, the report says. Some experienced persistent debilitating symptoms while others experienced a relapse.

The report says 1 percent of COVID claimants died from the disease, but 12 percent of those who were hospitalized did.

Claimants who were hospitalized and suffered long-COVID had longer duration claims. Medical treatment lasted an average of 159 days for hospitalized COVID claimants, with 89 days of that on temporary disability for the long-COVID patients. For long-COVID claimants who were not hospitalized, the duration of medical treatment was 93 days and temporary disability was 64 days.

Medical treatment for COVID claimants who were hospitalized but did not experience long-term symptoms was 26 days, with 35 days of indemnity benefits. For claimants who were not hospitalized and did not have long-COVID, medical treatment lasted 11 days and indemnity payments 19 days.

The data indicates that COVID-19 patients become less likely to exhibit long-term symptoms over time. While 47 percent of hospitalized COVID claimants reported long-COVID within the 270-day post-treatment window, only 14 percent of those claimants reported symptoms after 240 days. For the 20 percent of non-hospitalized COVID claimants who reported long-COVID symptoms, only 4 percent did after 240 days.

The report says that because data was collected only through the first quarter of 2022, the impact of more infectious Omnicron COVID variant on long-COVID is unknown.

“However, we feel encouraged and reassured by the progress that has been made toward prevention and more effective treatments for COVID-19 infections,” the report concludes.