Covid symptom checkers failed to identify severe cases – study
8 March 2021, 23:34
Concerns have been raised the tool used to assess Covid-19 online might miss severe cases.
Symptom checkers for Covid-19 may have guided people to stay at home when they needed to seek medical help, a new study has suggested.
The authors said that if the NHS 111 Covid-19 symptom checker is used as a “sole initial point of healthcare contact” it could lead to people delaying in seeking care, which could increase the risk of disease or death.
For instance, the symptom checker would instruct a a 72-year-old person, who has had a fever and a cough for a week, to “stay at home with no clinical, nursing or healthcare contact”, according to academics from Gibraltar Health Authority.
But NHS Digital said the study was “based on an early version of the tool”.
The study, published in the journal BMJ Health and Care Informatics, examined how national symptom checkers worked against simulated cases of Covid-19, varying in risk and severity.
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National symptom checkers were introduced by many countries in a bid to reduce the burden faced by health services.
People can input symptoms – usually online or via an app – and from the information entered the algorithm produces some advice.
It is hoped these assessments would effectively spot those who would benefit from being assessed by a medic.
Academics set out to examine the symptom checkers created by five different nations – Singapore, Japan, Norway, the UK (though the English symptom checker) and the US.
Researchers came up with 52 simulated cases with varying risk factors and entered them into the symptom checkers.
The authors examined how many of the cases would have been referred patients to seek help.
Singapore had the highest overall referral rate at 88% and the US had the lowest at 38%. The NHS system triaged 44% of cases to healthcare contact.
The authors said the US and English system triaged a “significant number” of cases to “stay home” that would typically have required early clinical assessment.
“The UK’s 111 Covid-19 symptom checker frequently triaged possible severe Covid-19 and bacterial pneumonia to stay at home with no follow-up and is likely to have delayed treatment for sepsis and severe Covid-19,” the authors wrote.
They added: “The low case fatality nations’ (Singapore and Japan) symptom checkers triaged in twice as many cases for direct clinical assessment than the higher case fatality nations (the US and UK).
“Of clinical concern was the failure of both the US and UK symptom checkers to triage cases simulating bacterial pneumonia, sepsis and severe Covid-19 on to any healthcare contact.”
They said the wording of some of the questions on the 111 symptom tracker encourage the self-reporting towards lower categories of illness.
“Our case simulation demonstrated that answering the moderately severe answer still triages patients to self-isolate with no healthcare contact,” they wrote.
“As such, patients with cough and fever for seven days would have to be so severely unwell that they are unable to do anything they usually do to be triaged to any clinical contact.
“Our case simulation study indicates that both the ‘111 Covid-19 symptom checker’ and the ‘CDC coronavirus symptom checker’, if used as the sole initial point of healthcare contact, are likely to delay presentations of serious medical conditions to appropriate care, and as such, are likely to confer an increased risk of morbidity and mortality.
“Both symptom checkers maintain a high threshold for referring onward to clinical contact, triaging the majority of patients to stay home with no clinical contact.”
NHS Digital said in a statement: “NHS 111 online is not a diagnostic tool. It allows people to assess their symptoms and signposts to other NHS services as required.
“This simulation study was based on an early version of the tool.
“Over the past year it has been continually revised and updated in response to new scientific information, government guidance and public health strategies.”
