Risk of chronic fatigue syndrome after COVID-19: A retrospective cohort study of 3227281 patients, 2024, Chen et al

Background
Many patients who recovered from COVID-19 still suffer from chronic fatigue syndrome (CFS). It was observed that patients with comorbidities were more prone to developing CFS. This research investigates the risk of post-COVID-19 CFS to assist healthcare professionals in reducing the risk of CFS.

Methods
A retrospective cohort study is conducted to investigate the risk of post-COVID-19 CFS based on the TriNetX-sourced electronic health records. Factors including age, sex, race, vaccination, and severity of COVID-19 are analysed. Propensity score matching was applied to balance COVID-19 and non-COVID-19 cohorts. Kaplan-Meier analysis and Cox proportional hazard model were used to perform the relationship between COVID-19 and CFS risk.

Results
This research involved 3227281 patients with COVID-19 and 3227281 with non-COVID-19 between 1st January 2020 and 31st December 2023. The incidence of CFS was higher in the COVID-19 group compared to the non-COVID-19 group at 1 follow-up intervals (HR 1.59, 95% CI = 1.54-1.63). Subgroup analysis revealed increased CFS risk across different age groups (>18), sexes, races, and comorbid conditions, with notable variations.

Conclusions
COVID-19 patients have a higher risk of developing CFS compared to individuals without COVID-19. The increased risk is particularly significant in adults aged 18 years and older.

Link | PDF (Journal of Infection and Public Health, October 2024, open access)

 

Unfortunately the main definition of CFS was the ICD-10-CM R53.82 code; G93.3 was only considered in addition to R53.82 in a sensitivity analysis:

 

So if we follow the usual 90% undiagnosed, the real number should be close to 10x?

 

Main results were:

Most confounders did not have a significant effect on the risk of CFS. It was only a bit higher in females and slightly lower in young people < 18 years. Also noted that the risk was higher in those without depression versus those with depression.

 

Unfortunately, this study uses ICD-10-CM code R53.82, which is for Chronic Fatigue. That probably explains the incidence of 0.2% after 12 months for the "non-covid" controls (tho that just means no positive covid test recorded). Way too high for ME/CFS.

Also, they don't check if the chronic fatigue resolves. And CF is normally for at least 3 months, yet main results in Fig 2 shows rates increasing for the first 3 months after infection when CF post-Covid shouldn't be possible. Who knows how this code was actually applied.

They said they did a sensitivity analysis including G93.3 (PVFS), but I couldn't see the results, either by skimming or searching the document.

Also, diagnostic code use in the US for ME is all over the place, though apparently is fixed (at least in terms of allowing a correct diagnosis that is not too hard to find) from sometime in 2022 thanks to lobbying by patient groups inc #MEAction (I think it is now g93.32) But this data set includes data before then, from 2020 to 2022 (whenever the fix happened).

I don't think this data can bear much weight.