Webdesk:
Analysis of data from the COVID Symptom Study app, led by researchers from King’s College London, reveals that there are six distinct ‘types’ of COVID-19, each distinguished by a particular cluster of symptoms.
Moreover, the team found that these types differed in the severity of the disease and the need for respiratory support during hospitalization.
The findings have major implications for clinical management of COVID-19 and could help doctors predict who is most at risk and likely to need hospital care in the second wave of coronavirus infections.
Although continuous cough, fever, and loss of smell (anosmia) are usually highlighted as the three key symptoms of COVID-19, data gathered from app users shows that people can experience a wide range of different symptoms including headaches, muscle pains, fatigue, diarrhea, confusion, loss of appetite, shortness of breath and more. The progression and outcomes also vary significantly between people, ranging from mild flu-like symptoms or a simple rash to severe or fatal disease.
To find out whether particular symptoms tend to appear together and how this related to the progression of the disease, the research team used a machine-learning algorithm to analyze data from a subset of around 1,600 users in the UK and US with confirmed COVID-19 who had regularly logged their symptoms using the app in March and April.
The analysis revealed six specific groupings of symptoms emerging at characteristic time points in the progression of the illness, representing six distinct ‘types’ of COVID-19. The algorithm was then tested by running it on a second independent dataset of 1,000 users in the UK, US, and Sweden, who had logged their symptoms during May.
The six clusters are as follows:
All people reporting symptoms experienced headaches and loss of smell, with varying combinations of additional symptoms at various times. Some of these, such as confusion, abdominal pain, and shortness of breath, are not widely known as COVID-19 symptoms, yet are hallmarks of the most severe forms of the disease.
1- (‘flu-like’ with no fever): Headache, loss of smell, muscle pains, cough, sore throat, chest pain, no fever.
2- (‘flu-like’ with fever): Headache, loss of smell, cough, sore throat, hoarseness, fever, loss of appetite.
3- (gastrointestinal): Headache, loss of smell, loss of appetite, diarrhea, sore throat, chest pain, no cough.
4- (severe level one, fatigue): Headache, loss of smell, cough, fever, hoarseness, chest pain, fatigue.
5- (severe level two, confusion): Headache, loss of smell, loss of appetite, cough, fever, hoarseness, sore throat, chest pain, fatigue, confusion, muscle pain.
6- (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.
Next, the team investigated whether people experiencing particular symptom clusters were more likely to require breathing support in the form of ventilation or additional oxygen.
They discovered that only 1.5% of people with cluster 1, 4.4% of people with cluster 2, and 3.3% of people with cluster 3 COVID-19 required breathing support. These figures were 8.6%, 9.9%, and 19.8% for clusters 4,5 and 6 respectively. Furthermore, nearly half of the patients in cluster 6 ended up in the hospital, compared with just 16% of those in cluster 1.
Broadly, people with cluster 4,5 or 6 COVID-19 symptoms tended to be older and frailer, and were more likely to be overweight and have pre-existing conditions such as diabetes or lung disease than those with type 1,2 or 3.
The researchers then developed a model combining information about age, sex, BMI, and pre-existing conditions together with symptoms gathered over just five days from the onset of the illness.
