Phase-dependent trends in the prevalence of [ME/CFS] related to long COVID: A criteria-based retrospective study in Japan, 2024, Morita+

[SNT Gatchaman]

Phase-dependent trends in the prevalence of myalgic encephalomyelitis / chronic fatigue syndrome ME/CFS related to long COVID: A criteria-based retrospective study in Japan
Satoru Morita; Kazuki Tokumasu; Yuki Otsuka; Hiroyuki Honda; Yasuhiro Nakano; Naruhiko Sunada; Yasue Sakurada; Yui Matsuda; Yoshiaki Soejima; Keigo Ueda; Fumio Otsuka

BACKGROUND
The characteristics of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) related to COVID-19 have remained uncertain. To elucidate the clinical trend of ME/CFS induced by long COVID, we examined data for patients who visited our outpatient clinic established in a university hospital during the period from Feb 2021 to July 2023.

METHODS
Long COVID patients were classified into two groups, an ME/CFS group and a non-ME/CFS group, based on three diagnostic criteria.

RESULTS
The prevalence of ME/CFS in the long COVID patients was 8.4% (62 of 739 cases; female: 51.6%) and factors related to ME/CFS were severe illness, smoking and alcohol drinking habits, and fewer vaccinations. The frequency of ME/CFS decreased from 23.9% in the Preceding period to 13.7% in the Delta-dominant period and to 3.3% in the Omicron-dominant period. Fatigue and headache were commonly frequent complaints in the ME/CFS group, and the frequency of poor concentration in the ME/CFS group was higher in the Omicron period. Serum ferritin levels were significantly higher in female patients in the ME/CFS group infected in the Preceding period. In the ME/CFS group, the proportion of patients complaining of brain fog significantly increased from 22.2% in the Preceding period to 47.9% in the Delta period and to 81.3% in the Omicron period. The percentage of patients who had received vaccination was lower in the ME/CFS group than the non-ME/CFS group over the study period, whereas there were no differences in the vaccination rate between the groups in each period.

CONCLUSIONS
The proportion of long COVID patients who developed ME/CFS strictly diagnosed by three criteria was lower among patients infected in the Omicron phase than among patients infected in the other phases, while the proportion of patients with brain fog inversely increased. Attention should be paid to the variant-dependent trends of ME/CFS triggered by long COVID.

Link | PDF (PLOS ONE) [Open Access]

 

[bobbler]

This one has made me think of @adambeyoncelowe ’s recent post in the consensus/definition thread specifically the issues regarding consistency and long covid

 

[Andy]

"We defined long COVID as a condition in which symptoms remain for longer than one month after the onset of COVID-19"

"The Fukuda Criteria [10], Canadian Consensus Criteria [11, 13] and IOM Criteria [25] are frequently used sets of criteria for diagnosing ME/CFS [9], and thus long COVID patients who met all of the three sets of criteria were diagnosed with ME/CFS to establish the ME/CFS group in the present study."

 

[Andy]

Ref 9 is to Clinical Characteristics of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) Diagnosed in Patients with Long COVID, 2022, Tokumasu et al

 

[Hutan]

The prevalence of ME/CFS in the long COVID patients was 8.4% (62 of 739 cases; female: 51.6%) and factors related to ME/CFS were severe illness, smoking and alcohol drinking habits, and fewer vaccinations.

That's a low proportion the people with Long Covid. I wonder if the requirement to meet the three criteria and the interpretations of each required symptom was overly demanding? The female percentage is a bit unusual too.

ME/CFS is a degenerative disease characterized by various multisystemic symptoms, and ME/CFS is diagnosed on the basis of symptoms persisting for more than 6 months including pathological fatigue, which refers to significant physical and mental exhaustion that markedly decreases activity levels, is not a result of exertion, is not alleviated by rest and is unexplained, post-exertional fatigue, sleep disturbances, pain, neurological dysfunction, and cognitive disorder

Possibly, all it would take for someone to not get an ME/CFS diagnosis at this clinic is for the patient to think to themselves something like 'I do usually feel a bit better after a nap, or after resting' and to not tick a box of 'fatigue not alleviated by rest'.

In addition, the proportion of long COVID patients meeting the IOM criteria was estimated to be approximately 10% [17].

That is completely wrong. The '10% with ME/CFS' in reference 17 was supposed to be applied to everyone who had a Covid-19 infection, not to people with Long Covid turning up at a Long Covid clinic.
Will COVID-19 Lead to Myalgic Encephalomyelitis/Chronic Fatigue Syndrome? Komaroff and Bateman
It was also very early in the pandemic, the authors of reference 17 noted that not many people in the US had had Covid-19 6 months or more ago. The authors of reference 17 estimated the 10% figure based on what had happened in other infectious diseases that were associated with triggering ME/CFS at six months. If the authors of this 2024 Japanese paper can get that so wrong, it makes me think they might not have paid enough attention to other things.