COVID-19 tracking app may not be good predictor: Study

Researchers have now indicated that tracking symptoms affiliated with the novel coronavirus (COVID-19) through an app may not be a good predictor of the spread of the disease.

Over the course of 2020, as the COVID-19 has spread across the globe causing extensive illness and economic havoc to communities everywhere, health care providers and the general public have been eager to find a way to identify the illness.

"In the absence of readily available tests, scientists have worked to identify clues to detect those who might have the illness as a way to combat the spread of the virus," said study authors from Oxford University Press in the UK.

A recent study, published in Nature Medicine journal, suggested that a prediction score combining loss of smell and taste, fatigue, cough, and loss of appetite - collected through an app - was able to prospectively identify people at risk of COVID-19.

For the current findings, published in the journal Family Practice, the research team here compared the main features of the population involved in the Nature Medicine study, and the performance of their score, with data from a cross-sectional study conducted between March 24 and April 29, 2020, and applied the Nature Medicine model to these data.

Applying the probability threshold in the Nature Medicine study to these data indicated that 41 per cent of positive tests were false positives, while 17 per cent of negative tests were false negatives.

In the Family Practice study, general practitioners referred to most patients because they were complaining of COVID-like symptoms.

"Indeed, nearly half the patients in the sample reported fever (45.4 per cent), reflecting the common reason for doctors to refer patients to testing at the time these data were collected," the authors wrote.

Fever was registered in the app in the Nature Medicine study by only one-third of patients.

In conclusion, while real-time symptom collection through an app seems to be an attractive method to screen for potential infections, and the Nature Medicine study confirms the crucial value of specific symptoms such as loss of smell and taste, the score proposed in the study does not appear to perform well in a primary care population.

"These results confirm the crucial role of laboratory testing in COVID-19 and the need to support research on COVID-19 in primary care populations," said the letter's lead author Benoit Tudrej.