Chronic fatigue syndrome (CFS), also known as myalgic encephalomyelitis (ME), is a condition characterized by severe fatigue that shows no improvement with bed rest, and which may be exacerbated by physical or mental exertion.
In the US, a person may be diagnosed with CFS if they experience severe chronic fatigue for at least 6 months that is not due to ongoing exertion or other conditions linked to fatigue.
They must also have at least four of eight symptoms, which include unrefreshing sleep, muscle pain, headache and frequent or recurring sore throat.
In the UK, severe chronic fatigue lasting 3 months or longer warrants a CFS diagnosis.
According to the Centers for Disease Control and Prevention (CDC), more than 1 million people in the US have CFS. The condition is more common among women than men and people in their 40s and 50s, though CFS can affect people of any age.
Teens with CFS miss half a school day each week
For their study, published in the journal Pediatrics, lead author Dr. Simon Collin, of the UK's University of Bristol, and colleagues set out to estimate the prevalence of CFS among children aged 16 years.
The team analyzed the data of 5,756 children who were part of the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort - also known as "Children of the 90s." The study enrolled more than 14,000 expectant mothers in 1991-1992 and continues to track the health of mothers, their partners and their children.
Specifically, Dr. Collin and colleagues analyzed information from questionnaires completed by parents and children, which disclosed any incidence of unexplained severe fatigue.
Additionally, the researchers used data from the National Pupil Database to estimate the number of missed school days as a result of CFS.
Overall, the researchers calculated that 1.9% of 16-year-olds - almost 1 in 50 - were affected by CFS lasting at least 6 months, while almost 3% had CFS lasting 3 months or longer.
Compared with children without CFS, the researchers found that those with the condition missed around half a day of school each week.
Furthermore, children with CFS were more likely to come from families with greater adversity, defined by the researchers as families with poor housing, financial problems and mothers with lack of practical and/or emotional support.
This latter finding challenges the popular notion that CFS is more likely to affect middle-class individuals, according to the authors.
"This is an important study because it shows that CFS/ME is much more common in teenagers than previously recognized," says senior author Dr. Esther Crawley, also of the University of Bristol. "As pediatricians, we need to get better at identifying CFS/ME, particularly in those children from disadvantaged backgrounds who may be less able to access specialist care."
Findings highlight how common CFS is among adolescents
Diagnosing CFS is challenging. There is currently no lab test for the condition, symptoms vary significantly from person to person, and symptoms of CFS are common among many other illnesses, making it hard to spot.
What is more, there is still some debate as to whether CFS should be classified as a legitimate medical condition, despite a 2015 report from the Institute of Medicine (IOM) claiming that CFS is a "serious illness that requires timely diagnosis and appropriate care."
Previous research from Dr. Collin and colleagues, for example, found that 94% of children with CFS reported being disbelieved.
The team hopes that this latest research will highlight how common CFS really is among children adolescents.
Mary-Jane Willows, chief executive of Association of Young People with ME - who was not involved in the study - comments:
"We are encouraged by the results of this study as, at last, our children, their families and those fighting for a diagnosis have the evidence they need. Evidence confirming the condition as being not only really common but, more significantly, evidence reflecting the high level of suffering with which they are forced to live."
In November last year, Medical News Today discussed the challenges in diagnosing CFS and whether some effective treatments for the condition could be on the horizon.