Major flaws in the published research on long COVID are likely to have exaggerated the true risks of developing the condition, according to a new study reported today.
Researchers from the University of California San Francisco, USA, University of Southern Denmark, Denmark, Public Health England, and St George’s University of London, London, UK, say issues including broad definitions and a lack of appropriate – or any – comparison groups in studies looking at the incidence, prevalence, and epidemiology have distorted the risks.
Writing in BMJ Evidence Based Medicine, they warn the inclusion of poorly conducted studies into systematic reviews and pooled data analyses have also overstated the risk.
They say this could lead to increased public anxiety and healthcare spend; misdiagnoses; and diversion of funds from those who have other long-term conditions secondary to COVID-19 infection.
While the results of high-quality population studies on long COVID in both adults and children have been reassuring, they claim the body of research “is replete with studies with critical biases”.
The researchers say that while after-effects of COVID-19 infection include post-ICU syndrome and shortness of breath following pneumonia, these are common to many upper respiratory viruses.
None of the working definitions of long COVID used by influential health bodies, such as the US Centers for Disease Control and Prevention, the World Health Organization, the UK National Institute for Health and Care Excellence (NICE), requires a causal link between SARS-CoV2 and a range of symptoms.
The researchers call for the term ‘long COVID’ be retired in favour of different terms for specific after effects and call for long COVID studies to be properly matched to cases.
They write: “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.”
They add: “Ultimately, biomedicine must seek to aid all people who are suffering. 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.”
Høeg TB, Ladhani S, Prasad V. Analysis: How methodological pitfalls have created widespread misunderstanding about long COVID. BMJ Evidence Based Medicine. 26 September 2023; doi 10.1136/bmjebm-2023-112338
Leave a Reply