[Preprint] Association between Parents Experiencing Ongoing Problems from Covid-19 and Adolescents Reporting Long Covid..., 2022, Ladhani et al

Abstract

In a national cohort of 12,788 adolescents, those reporting parents experiencing ongoing problems from COVID-19 had 1.79-fold (95%CI: 1.58-2.02) higher odds of experiencing LONG COVID 6 months after a SARS-CoV-2 PCR-test than those reporting parents without ongoing symptoms, independent of age, sex, deprivation and SARS-CoV-2 infection status.

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This is from the CLoCk study.

 

This seems to have been the CLOCK study's originally intended definition of long covid:

https://adc.bmj.com/content/107/7/674

It's not very clear but it seems that this definition of long covid was then used in this study

Did the authors engage in case definition switching or am I misunderstanding something?

 

This is such a bizarre study to begin with. Why adolescents? Completely arbitrary.

A "study" featuring Chalder and Crawley, uninterpretable and mostly useless. On brand. The jobs program keeps on giving jobs to people who don't deserve them. Besides that I have no clue what purpose this study serves.

Notable that on the lead author of the study tweeting about it, many of the comments are just trolls going about "hYpoCHonDriacs" and other nonsense.

 

Yes, I think they have done some shifting in order to arrive at the conclusions they want to arrive at here. The corresponding author's tweets here make it clear that they're trying to play a gotcha game by conflating any kind of symptom at 6 months that affects the person in any way with Long Covid:

https://twitter.com/user/status/1560632249783095297


I think in this case there are probably a number of different factors here that could explain the difference (Covid infections not diagnosed via PCR leading to Long Covid with higher likelihood due to genetic factors, higher likelihood of other post-infectious disease due to genetic factors, mental health effects of having parent with Long Covid, higher propensity to report symptoms correlated with higher propensity to report parent's LC (this study is not based on self-identified LC, but LC identified by the child), possible genetic links between susceptibility to LC and other health conditions, and so on).

The authors obviously already have their own beliefs and are casting about in the data to find ways to justify them.

 

The authors are labeling adolescents that are SARS-CoV-2 negative as having long covid. In table 1 they report 28% prevalence of long covid in this group while the prevalence should be 0% if they used a definition of long covid that required being SARS-CoV-2 positive.

They also measured symptoms at the six months timepoint instead of 12 weeks. This would weaken an association with prolonged symptoms after infection because in a good portion the symptoms will not last six months.

Measuring symptoms at a single timepoint could also result in misclassification: this method cannot distinguish between people whose symptoms appeared shortly after infection and persisted for months, and those who happened to have non-persistent symptoms, without a clear temporal relationship to infection, at the timepoint.

That they define long covid as being related to being very worried or sad is also a deviation from the original case defintion.

It would now be useful to clearly show that the authors engaged in case definition switching by finding evidence that they originally intended to use the Delphi process derived case defintion mentioned above.