A new survey of Dutch doctors and their patients suggests that chronic fatigue syndrome affects only about 1 in 900 teenagers - but takes a heavy toll.

Among those teens diagnosed with chronic fatigue syndrome, or CFS, more than 90 percent had at least missed “considerable” school in the last 6 months, with some saying they had not attended school at all during that time.

CFS “is a condition with severe implications for school participation etc, necessitating adequate diagnosis and treatment,” study author Dr. Sanne Nijhof of the University Medical Center Utrecht in the Netherlands told Reuters Health.

The impact is felt by many more people than the patient, said Dr. Katharine Rimes, who was not involved in the study.

“Missing substantial amounts of school can potentially have profound effects on their educational, social and emotional development,” explained Rimes, based at King’s College London. “It also has potentially serious impact on the family. If the child is off school, one parent - usually the mother - usually has to stay at home to care for them, and often give up their job altogether. This can obviously have adverse financial and psychological effects.”

CFS is a long-term debilitating condition of disabling physical and mental fatigue, poor concentration and memory, disturbed sleep and muscle and joint pain.

There is no cure for CFS and scientists don’t know what causes it. Many sufferers say they think their illness started after a viral infection, but suggested links to a virus known as XMRV were shown in a recent scientific paper to have been based on contaminated samples in a lab (see Reuters Health story of December 20, 2010).

This estimation of the rate of CFS among teens, published in the journal Pediatrics, is considerably lower than previous estimates of CFS among adults. In one Dutch study, 1 percent of adults said they had the condition.

According to the U.S. Centers for Disease Control and Prevention, millions of Americans have CFS, perhaps 80 percent of whom may not realize they have it.

Nijhof explained that trying to understand why his estimate for teens is lower than previous ones for adults “would be speculative,” since his study did not include adults, and different studies use different methods.

To get a better idea of how many teens in the Netherlands are affected by CFS, Nijhof and colleagues sent questionnaires to a group of general practitioners and reviewed a national registry of pediatric disorders, in which pediatricians report new cases of disorders affecting their patients. The researchers also mailed surveys to patients asking about the condition’s impact on their lives.

Less than half of general practitioners returned the survey. Based on their responses, the authors estimated that 111 out of every 100,000 teens, or 0.11 percent, were diagnosed with CFS. Records from pediatricians suggested that 12 out of every 100,000 teens, or 0.012 percent, were newly diagnosed with CFS every year.

Patients were an average of 15 years old when the illness began. Half experienced symptoms for at least 17 months before they were diagnosed. In one-fifth of patients, the illness began after a severe infection. CFS occurred in five times as many girls as boys.

Of potential concern, the authors note, is that the condition appears to be “under-recognized” by primary care physicians. Only half of all general practitioners who agreed to participate in the study said they accepted CFS as a distinct diagnosis, versus 96 percent of the pediatricians consulted during the study. And nearly 75 percent of teens with CFS were not diagnosed by their general practitioners. This lack of awareness probably stems from the condition’s infrequency, said Nijhof. “The average GP will not have a CFS patient in their practice.”

“Adolescents with severe and long-lasting fatigue should be referred to a pediatrician,” agreed Rimes in an email.

Although only half of general practitioners responded to the survey, non-responders did not appear to be any different from responders, so the results from half the group likely represent the population overall, Nijhof said in an email.

It’s an important study, despite its potential limitations, said Rimes, in part because CFS is not studied in teens nearly as often as adults. “The disabling nature of the condition has the potential to have a serious adverse impact on the normal cognitive, emotional, and social developmental processes that occur at this age.”

SOURCE: Pediatrics, online April 18, 2011.