The post-COVID syndrome known as long COVID has four main subtypes defined by different clusters of symptoms, according to a study led by Weill Cornell Medicine researchers.
This study, published in the journal Nature Medicine, is the largest of its kind to examine prolonged COVID. The researchers, representing physicians and computer scientists, used a machine learning algorithm to detect symptom patterns in the health records of nearly 35,000 US patients. who tested positive for SARS-CoV-2 infection and later developed persistent COVID-19-like symptoms.
Of the four main patterns detected, one had heart and kidney problems and included a relatively high proportion of patients infected in the early months of the pandemic in the US. Another pattern included respiratory problems, anxiety, sleep disturbances, and other symptoms such as headache and chest pain; nearly two-thirds of patients with this pattern were women.
By initially analyzing the patient data set, the machine learning algorithm detected four main symptom patterns. The first, which accounted for about 34% of patients, was dominated by symptoms related to the heart, kidneys, and circulation. Patients in this group, compared with those in other groups, were older on average (median age 65), more likely to be male (49%), had a relatively high rate of COVID hospitalization (61%), and had relatively more pre- existing conditions.
The second pattern of symptoms, comparable in frequency (33% of patients) to the first, was dominated by respiratory and sleep problems, anxiety, headache, and chest pain. Patients with this pattern were mostly women (63%), with a median age of 51 years and a much lower rate (31%) of COVID hospitalization. Nearly two-thirds of patients in this group tested positive for SARS-CoV-2 during subsequent waves, from November 2020 to November 2021. Pre-existing conditions in this group focused on respiratory problems such as chronic obstructive pulmonary disorder and asthma. .
The other two symptom patterns were dominated, respectively, by musculoskeletal and nervous system symptoms, including arthritis (23% of patients), and by a combination of digestive and respiratory symptoms (10%).
Only in the first pattern of symptoms was the sex ratio approximately 1:1; in the other three, female patients constituted a significant majority (more than 60%).
Researchers are currently tracking research on several lines, including defining long patterns of COVID symptoms so they can be easily identified from electronic health records, identifying risk factors for different symptom patterns, and identifying existing treatments that can be repurposed to help long-term COVID patients.