Almost a quarter of COVID-19 patients did not meet the criteria of characteristic symptoms

A new study conducted by a research team from the Landspítali University Hospital and the University of Iceland on the frequency and development of symptoms among COVID-19 patients during the first wave in Iceland suggests that almost a quarter would not have been diagnosed with the disease or would have had a delayed diagnosis if only those who fulfilled the WHO criteria for symptoms had been allowed to be tested. These results were published yesterday in the British Medical Journal. The study shows, furthermore, that almost half of the patients had gastrointestinal symptoms. 

The first author of the article is Elías Eyþórsson, postdoc and MD, but he worked on the study under the supervision of Runólfur Pálsson and Martin Ingi Siguðrsson, professors at the University of Iceland's Faculty of Medicine, and in collaboration with a large team of research scientists, medical doctors, and medical students at the Landspítali University Hospital and the University of Iceland.

Most studies on the symptoms of COVID-19 have, until now, been based on information from patients who have been hospitalised. For some time those who did not need to be admitted to hospital were either not diagnosed with the disease or were without help from members of the health profession during their illness. The few studies done on symptoms in all individuals diagnosed with COVID-19 have almost exclusively been based on questionnaires put to patients at diagnosis. The consequence is that the manifestation of serious COVID-19 cases have been well documented, but information on others diagnosed with COVID-19 has been lacking.  This is important because decisions on testing for COVID-19 is often based on well defined symptoms, so if the pattern of symptoms is different in patients with milder forms of the disease this might lead to less inclination to test them.      

Over a fifth did not meet the symptom criteria of WHO

The study by Elías et al was based on data gathered at the outpatient COVID-19 clinic at Landspítali University Hospital. Everyone diagnosed with COVID-19 (positive PCR ro SARS-CoV-2) was registered for the clinic's telephone service, involving frequent communication with nurses and doctors estimating the patients' well-being and providing advice. Each call also involved asking whether any of 19 defined symptoms were present and the severity of the disease estimated. Answers to the these questions were systematically registered in a special form designed for the clinic, and the results were updated after each call. The study included all of the 1797 who were diagnosed with COVID-19 from 28 February to 30 April 2020, but special focus was placed on the 1,564 who were diagnosed after the registration form was implemented. 

The study results proved interesting. The most common symptoms of COVID-19 were weakness (75%), headache (73%), and cough (73%). Only 48% got a fever and 58% had reduced sense of taste whereas 57% had reduced sense of smell. All of the symptoms were most common at the outset of the illness, apart from the reduced sense of taste and smell that were more commonly felt on the eighth day after the first symptoms. Even though COVID-19 is often referred to as a respiratory disease it is noteworthy that 48% had gastrointestinal symptoms. The study also shows that 22% of those diagnosed did not fulfil the WHO criteria for symptoms prior to testing, and 14% did not meet the CDC case definition for COVID-19. The results indicate that up to 24% of those diagnosed with COVID-19 would not have been diagnosed, or their diagnosis would have been delayed if only those who met the above mentioned criteria for symptoms had been allowed to be tested. 

This research adds important knowledge on the development of symptoms in COVID-19 patients. Former research is likely to have over-estimated the frequency of symptoms common in seriously ill individuals. Furthermore, the study shows that the pattern of symptoms varies greatly among those diagnosed with COVID-19 and the prerequisites of having certain symptoms to be tested will inevitably lead to under diagnosis. 

The article is accessible on the British Medical Journal's website.