Long COVID risks are ‘distorted by flawed research’, study finds

The risk of contracting long COVID may have been exaggerated due to flawed research, leading to unnecessarily high levels of anxiety about suffering from it, a new study has suggested.

“Major flaws” in the literature on the condition likely exaggerated the true threat of contracting it, the new research argues.

For most people with COVID-19, they feel better within days or weeks, but some can have symptoms for longer than three months.

Fatigue, brain fog, chest pain and shortness of breath are reported as symptoms by those who have long COVID – which is officially known as post-acute sequelae of COVID-19 (PASC).

Now, researchers from the UK, along with Denmark and the USA, say “many scientific publications” overestimated the prevalence of long COVID because of “overly broad definitions, lack of control groups, inappropriate control groups, and other methodological flaws”.

Instead, the authors of the new study argue that the symptoms are common among upper respiratory viruses.

The research team said this lack of definition could end up leading to an increase in healthcare spending and more anxiety, as well as misdiagnoses and a diversion of funds.

Concerns about too many symptoms and no required link to COVID

Published in the British Medical Journal’s Evidence-Based Medicine, the new paper looked at the definition of the condition by several global health organisations – including the National Institute for Health and Care Excellence (NICE) and the World Health Organisation (WHO).

The study argues none of the definitions “requires a causal link” to COVID-19 infection, adding any symptoms that happen after a confirmed or suspected infection could be considered consistent with long COVID.

“In general, in the scientific literature, imprecise definitions have resulted in more than 200 symptoms being associated with the condition termed long COVID,” the researchers said.

Researchers also said the studies in the early stages of the pandemic are more likely to have included fewer patients with mild or no symptoms, which could have led to a sampling bias.

They said: “Our analysis indicates that, in addition to including appropriately matched controls, there is a need for better case definitions and more stringent (long COVID) criteria, which should include continuous symptoms after confirmed SARS-CoV-2 infection and take into consideration baseline characteristics, including physical and mental health, which may contribute to an individual’s post-COVID experience.”

Research in the future should include properly matched groups, the paper added, as well as “sufficient” follow-up time following infection.

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The study’s authors also want to see “internationally established” diagnostic criteria and called for future studies to avoid “umbrella terms” and instead “narrowly define” the symptoms.

“Ultimately, biomedicine must seek to aid all people who are suffering,” the research team added. “In order to do so, the best scientific methods and analysis must be applied.

“Inappropriate definitions and flawed methods do not serve those whom medicine seeks to help.

“Improving standards of evidence generation is the ideal method to take long COVID seriously, improve outcomes, and avoid the risks of misdiagnosis and inappropriate treatment.”

Study criticised for ‘some odd conclusions’

However, Dr Adam Jacobs, senior director of biostatistical science at Premier Research, said although the paper “makes some sensible points” it goes on “to draw some odd conclusions”.

He added: “It is, of course, inevitable that much of this literature is imperfect.

“Long COVID simply didn’t exist four years ago, so researchers have had to get to grips with a new and challenging topic at top speed.

“It is, therefore, not surprising that different studies have different estimates of the prevalence of long COVID, as studies have used different case definitions, different populations etc.”

Dr Jacobs said a survey by the Office for National Statistics (ONS), which was discontinued in March, found that 1.9 million people in the UK had long COVID.

He said this was a “staggeringly high” number.

“We don’t know how long those people will remain ill,” he added. “If we are lucky, most of them will be healthy again within a year or two.

“If we are unlucky, a large number of them may have a permanent disability.”