ONLINE Covid symptom checkers used by patients in the UK are failing to pick up signs of severe illness and may stop some people from seeking medical help in time, a study has found.

Researchers at the University of Gibraltar compared the ability of the national government-sponsored digital symptom checkers used in Singapore, Japan, the US and the UK, to correctly triage people in need of a medical assessment and/or treatment.

These included the Singapore Covid-19 Symptom Checker; Stop Covid-19 Symptom Checker (Japan); CDC Coronavirus Symptom Checker (US); and 111 Covid-19 Symptom Checker (UK).

They found that both the US and UK symptom checkers consistently failed to identify the symptoms of severe Covid, bacterial pneumonia, and sepsis, frequently advising these cases to stay home.

The authors write: "The stakes are high, in that a failure to triage serious medical conditions (such as severe Covid-19, bacterial pneumonia or sepsis) in for further assessment will inevitably lead to delayed treatment and higher mortality."

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It is believed to be the first time that the self-triage technology has been evaluated for safety and efficacy during a pandemic.

The findings are published today, in the online journal BMJ Health & Care Informatics.

Digital symptom checkers combine a series of set questions and pre-determined responses to advise a person on the most appropriate course of action.

Previous studies, in non-pandemic contexts, have also found "mixed and disappointing results", say the researchers.


They set out to determine whether the ones currently being promoted by governments for Covid were able to differentiate mild from severe disease, and how well they picked up Covid-19 ‘mimickers’ such as bacterial pneumonia and sepsis in 52 standardised case scenarios.

These combined various symptoms, such as cough, fever, shortness of breath with factors such as pre-existing conditions, patient's age, and duration and severity of symptoms.

The symptom checkers in Singapore and Japan triaged twice as many cases for direct clinical assessment compared to the symptom checkers in the US and UK.

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Singapore had the highest overall referral rate, at 88%, compared to 44% in the UK and 38% in the US. In Japan the referral rate was 77%.

The UK’s symptom checker frequently told patients with severe Covid-19 and bacterial pneumonia to stay home with no follow-up, and is likely to have delayed treatment for sepsis, severe Covid, and severe sepsis, note the researchers.

They warn that both the US and UK symptom checkers “are likely to delay presentations of serious medical conditions to appropriate care", adding: “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.”

This increases the risk of serious illness and death, say the researchers. 

Covid death rates in Singapore and Japan are comparatively low; in the US and the UK they are comparatively high.

Data from the National Records of Scotland also shows that more than 600 have died at home in Scotland with Covid since the beginning of the pandemic.

The researchers write that the UK's 111 symptom checker uses an algorithm which is overly complex and relies on "subjective, qualitative questions with multiple choices".

They added; "The 111 symptom checker seems to take on a much broader clinical role and attempts to triage out cases that would typically be triaged in or out of care based on an actual clinical assessment.

"For example, a 72year old person who presents with a seven-day history of fever and cough is triaged by the ‘111’ symptom checker to stay at home with no clinical, nursing or healthcare contact.

"Faced with such a clinical scenario, clinicians would typically insist on at least basic clinical observations (pulse, temperature, oxygen levels and so on) before considering triaging such a patient to stay at home."

The researchers acknowledge that by reducing physical contacts, symptom checkers can potentially save valuable resources and reduce viral spread, and they require fewer resources than phone and telemedicine triaging services.

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However, there is also “the potential for such patient-led assessment tools to worsen outcomes by delaying appropriate clinical assessment,” particularly if they are used as the only source of medical advice.

They recommend that symptom checkers "be subjected to the same level of evidenced based quality assurance as other diagnostic tests prior to implementation”.