Three main clusters of symptoms
Given the wide range of symptoms, long COVID likely represents a group of conditions, the authors wrote.
They found three main clusters. The largest, with roughly 80% of people with long COVID in the study, faced a broad spectrum of symptoms, ranging from fatigue to headache and pain. The second-largest group, (15%) mostly had symptoms having to do with mental health and thinking skills, including depression, anxiety, brain fog, and insomnia. The smallest group (5%) had mainly respiratory symptoms such as shortness of breath, coughing, and wheezing.
Putting symptoms in clusters will be important to start understanding what leads to long COVID, said Farha Ikramuddin, MD, a rehabilitation specialist at the University of Minnesota, Minneapolis.
She added that, while the symptoms listed in this paper are new in published research, she has certainly been seeing them over time in her long COVID clinic. (The researchers also used only coded health care data, so they were limited in what symptoms they could discover, she notes.)
Dr. Ikramuddin said a strength of the paper is its large size, but she also cautioned that it’s difficult to determine whether members of the comparison group truly had no COVID infection when the information is taken from their medical records. Often, people test at home or assume they have COVID and don’t test; therefore the information wouldn’t be recorded.
Evaluating nonhospitalized patients is also important, she said, as much of the research on long COVID has come from hospitalized patients, so little has been known about the symptoms of those with milder infections.
“Patients who have been hospitalized and have long COVID look very different from the patients who were not hospitalized,” Dr. Ikramuddin said.
One clear message from the paper, she said, is that listening and asking extensive questions about symptoms are important with patients who have had COVID.
“Counseling has also become very important for our patients in the pandemic,” she said.
It will also be important to do studies on returning to work for patients with long COVID to see how many are able to return and at what capacity, Dr. Ikramuddin said.
A version of this article first appeared on WebMD.com.