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ME/CFS affects women more severely than men

Published: 24 August 2023

Women with ME/CFS tend to have more symptoms and co-occurring conditions than men. This is according to initial results from the world’s largest study of the disease.

It has long been known that women are more likely to have ME/CFS (myalgic encephalomyelitis/chronic fatigue syndrome). But the DecodeME study has shown for the first time how their experience differs from men.

The study also shows that women who have had ME/CFS for more than 10 years are more likely to experience more severe symptoms as they age.

Experts analysed anonymous survey questionnaires from more than 17,000 people with ME/CFS. They include information on:

  • How long the respondent has had ME/CFS symptoms
  • When they were diagnosed
  • Whether they had any co-occurring conditions

The study confirmed the well-established sex bias among ME/CFS patients, with women making up 83.5% of respondents.

Two-thirds (66.7%) of women reported at least one active co-occurring condition. Just over half (52.7%) of men did so. Similarly, 39.2% of women and 28.6% of men reported at least one inactive co-occurring condition.

A condition was considered active if the participant had experienced symptoms in the preceding six months.

The most common active co-occurring condition were as follows:

  • Irritable bowel syndrome (41.3%)
  • Clinical depression (32.4%)
  • Fibromyalgia (29.5%)
  • Anaemia (14.1%)
  • Hypothyroidism (12.8%)

On average, women also reported more symptoms than men – 42% against 36%. The most common of these symptoms were brain fog, unrefreshing sleep and muscle pain.

Participants were also asked to define the severity of their illness from mild to very severe using definitions from the National Institute for Health and Care Excellence (NICE) guidelines.

Experts identified being a woman and having ME/CFS for more than 10 years are risk factors for severe illness. Symptoms increase in intensity as people age.

Experts also say a better understanding of how ME/CFS affects people is the first step to developing effective treatments. The study team from the University of Edinburgh are calling on more people with ME/CFS, aged 16 and over and based in the UK to take part in the study. Researchers want to recruit a further 6,000 participants.

The next stage of the study will see experts study at least 20,000 individual DNA samples. This will explore whether the disease is partly genetic. If so, then they will research its cause.

Professor Chris Ponting, study lead from the MRC Human Genetics Unit at the University of Edinburgh’s Institute of Genetics and Cancer, said: “ME/CFS is a devastating disease affecting a UK population the size of Derby. We discovered that the disease is worse for women, in older people, and many years after their ME/CFS started. Our hope is that DecodeME’s genetic results will shed light on why certain groups are more susceptible to ME/CFS than others.”

ME/CFS is a long-term neurological condition where an excessive increase in symptoms can be triggered by normal levels of exertion. It is estimated to affect more than a quarter of a million people in the UK, of all ages and from all social and economic backgrounds. Its key feature, called post-exertional malaise, is a delayed dramatic worsening of symptoms following minor physical effort. Other symptoms include pain, brain fog and extreme energy limitation that does not improve with rest. Causes are unknown and there is currently no diagnostic test or cure.

Alongside the University of Edinburgh, the study involves the charity Action for M.E., the Forward M.E. alliance of UK charities, and people who have experienced the condition. The study is funded by the Medical Research Council and the NIHR. Initial results from the study have been posted on NIHR Open Research.

The second stage of the study is being supported by Be Part of Research’s new UK-wide registry. This new tool gives researchers free and easy access to research-engaged volunteers across the UK - enabling them to recruit more effectively. It can match volunteers to studies based on age, ethnic group, gender, location and condition.

Be Part of Research is run by the NIHR, in collaboration with the devolved administrations. It helped recruit 120 volunteers to the DecodeME study as of May 2023.

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