Symptoms developed within the first week of the onset of a COVID-19 infection can determine the likelihood of a patient requiring serious medical attention by the end of week two, according to researchers at King’s College in London.
The new study, which wasn’t peer-reviewed but was replicated in an independent data set, could help doctors identify the patients who require care and treat them earlier, possibly saving lives. It showed a wide variety of outcomes and symptoms, some of which hadn’t previously been strongly connected to COVID-19.
“These findings have important implications for care and monitoring of people who are most vulnerable to severe COVID-19,” Dr. Claire Steves, of King’s College, said in a release. “If you can predict who these people are at day five, you have time to give them support and early interventions … simple care that could be given at home, preventing hospitalizations and saving lives.”
There were six distinct “types” of the virus that appeared in different “clusters” of symptoms in patients by the fifth day symptoms set in, according to an analysis of about 1,600 patients in the U.S. and U.K. who logged their symptoms during March and April. Most COVID-19 patients who require breathing support first visit a hospital around the 13th day after their first symptoms, researchers said, potentially shaving eight days off the typical timeline before medical intervention.
The six clusters can be broken down into two groups: three clusters of less severe symptoms — more prevalent in younger and healthier patients — and three clusters defined as “severe” symptoms, which were more likely to come in patients who were older or had preexisting conditions.
The researchers break them down as such, in order of severity with their key distinctions in bold:
- (‘flu-like’ with no fever): Headache, loss of smell, muscle pains, cough, sore throat, chest pain, no fever.
- (‘flu-like’ with fever): Headache, loss of smell, cough, sore throat, hoarseness, fever, loss of appetite.
- (gastrointestinal): Headache, loss of smell, loss of appetite, diarrhea, sore throat, chest pain, no cough.
- (severe level one, fatigue): Headache, loss of smell, cough, fever, hoarseness, chest pain, fatigue.
- (severe level two, confusion): Headache, loss of smell, loss of appetite, cough, fever, hoarseness, sore throat, chest pain, fatigue, confusion, muscle pain.
- (severe level three, abdominal and respiratory): Headache, loss of smell, loss of appetite, cough, fever, hoarseness, sore throat, chest pain, fatigue, confusion, muscle pain, shortness of breath, diarrhea, abdominal pain.
The first group made up the largest share of participants, with a sample of 462, while there were 315 in the second group, 216 in the third, 280 in the fourth, 213 in the fifth and 167 in the sixth and most severe cluster of symptoms.
All the patients who developed symptoms reported headaches, followed by a decreasing sense of smell. What happened after the first few days of symptoms set the groups apart.
Headaches faded for all but the two most severe groups, who also began to develop a sense of confusion after the first four or five days. Those two groups were also more likely to experience muscle pains and loss of appetite early on in the immune system’s response.
The three least severe clusters hardly reported any fatigue in their first week of symptoms, while that began to set in around day three or four for the three more severe clusters.
Only patients in the sixth and most severe cluster experienced abdominal pain — one of a handful of symptoms, including confusion and shortness of breath “not widely known as COVID-19 symptoms, yet are hallmarks of the most severe forms of the disease,” researchers wrote — which in some cases was reported on the first day a patient felt symptomatic.
Patients in the sixth cluster were 13 times more likely than those in the first to require breathing support and three times as likely to require hospitalization.
Researchers found 1.5% of people with cluster 1, 4.4% of people with cluster 2 and 3.3% of people with cluster 3 required breathing support, compared to 8.6%, 9.9% and 19.8% for clusters 4,5 and 6, respectively. Nearly half the patients in cluster 6 required hospitalization, compared to 16% of cluster 1 patients.
“Our study illustrates the importance of monitoring symptoms over time to make our predictions about individual risk and outcomes more sophisticated and accurate,” Dr. Carole Sudre, the study’s lead researcher, said in a release. “This approach is helping us to understand the unfolding story of this disease in each patient so they can get the best care.”