The Epidemiology of CFIDS

Congressman Porter, Congressman Fazio, Senator Gorton, Senator Reid and Members of Congress:

Thank you for the opportunity today to discuss the issue of Chronic Fatigue Syndrome (CFS), also known as Chronic Fatigue and Immune Dysfunction Syndrome (CFIDS), with you. My name is Karen Jordan, and I am a clinical psychologist working at DePaul University in Chicago. I am currently the project director of a large, community-based grant that is examining the prevalence of CFS in adults. This grant was generously funded through the National Institute of Allergy and Infectious Diseases. We have also been awarded a small supplement to begin some preliminary work in the area of the epidemiology of pediatric CFS.

As you may know, CFS is a complex illness characterized by severe, incapacitating fatigue as well as a host of physical complaints and neurological impairments. The symptoms are of a relapsing and remitting nature, often made worse by physical exertion of stress, and may persist for months or years. The majority of studies concerning CFS have concentrated on the adult population, with children and adolescents with CFS receiving decidedly less attention. However, the illness does strike children, presenting most commonly after puberty.

Two basic building blocks for understanding this disorder in children are currently being assembled, although both continue to need attention. First, a definition for children must be determined in order to facilitate research and communication about CFS. Second, we must determine how many children are affected by the disorder in order to develop programs to assist them in all realms, including medical, academic, social, and developmental.

At the present time, other than the adult criteria, there are no specific diagnostic criteria for children. The most common symptoms reported, besides fatigue, by pediatric CFS patients are headaches, sleep disturbance and cognitive impairment. The cognitive problems are often severe enough to interfere with school performance and other learning tasks. However, the typical pediatric CFS patient often presents appearing healthy, with only minor abnormalities present on laboratory testing and physical examination. This is in sharp contrast with the patient's reports of severely limited activity and numerous symptoms.

Lacking a definitive diagnostic test, it is imperative that criteria specific to children and adolescents be adopted to be used as a standard in future research. This is a necessary priority for valid and reliable research as groups of children need to be accurately identified according to one case definition in order to facilitate standardization across studies. Much of the current literature is skewed by the lack of a definition, as studies have included children who do not meet the adult criteria or who have the symptom of chronic fatigue (as distinct from CFS). Once a case definition has been proposed, testing as to its reliability and validity must be conducted.

Regarding the second basic building block of epidemiology, although to date no study has examined children and youth exclusively, prevalence estimates have been determined from larger population studies. Prevalence estimates for children under 10 have ranged from 0.0 per 100,000 (Dobbins et al., 1996) to 5.5 per 100,000 (Lloyd et al., 1990) for children under age 10 or 11. However, for children over age 10, prevalence estimates range from 2.7 per 100,000 (Dobbins et al, 1996) to 47.9 per 100,000 (Lloyd et al, 1990). Translating these figures into absolute numbers, based on the current US Census Bureau's population estimates, there would be approximately 2,132 children under 10 with CFS and anywhere between 1,025 and 18,185 adolescents with CFS. Much more work needs to be done to improve the estimates of the true incidence of CFS in young children and in adolescents.

A couple of notes should be made regarding these prevalence estimates. First, due to methodological problems, all stuies on pediatric and adolescent CFS probably underestimate the true prevalence of the disease. Thus, there may be many more unidentified cases in the population. Second, it should be noted that the prevalence estimate for the adolescent population cited by Lloyd is higher than their overall prevalence estimate of 37.1 cases per 100,000. Thus, adolescents may actually have a higher risk for developing CFS than some adult age groups.

A third factor that is vitally important is to understand the limitations CFS places on children's growth and development, both physically and cognitively. A CFS student's school performance is often severely negatively impacted by repeated absences and difficulty concentrating while in school. School districts are often reluctant to construct home-based school programs to accommodate these children's needs. We know from studies regarding other populations of chronically ill children that it is often difficult for them to compensate for lost time in school and to remain on target with their same-age peers. Furthermore, their social developments is often hindered by months in bed, isolated from friends and social activities.

With this information in mind, I would like to briefly describe the research that we have been conducting at DePaul University regarding the prevalence of CFS in children and adolescents. This research is ongoing, and thus the results presented are preliminary and many change as data continues to be collected.

The first stage of the adult CFS epidemiology project involves telephone calls to 26,000 randomly-generated telephone numbers in the Chicago area. A short screening interview is administered to a randomly selected adult. If the adult reports 6 months or more of fatigue, a longer questionnaire regarding symptoms of CFS is administered. I then review all the extended questionnaires and select those who meet the current CDC definitional criteria based on their answers to the questions posed by the interviewers. These selected individuals are then administered a psychiatric interview and medical evaluation in order to determine if they do indeed have CFS. The final stage of the study involves the administration of psychosocial instruments to assess factors such as coping styles, social support, and illness management.

Several months into data collection in the adult project, we added questions about children and adolescents in the household to the Stage I screening questionnaire. The following data is from this stage of data collection.

We have completed interviews with the randomly selected individuals in 15,673 households to date. Of these, 11,803 ere asked the questions regarding children and adolescents. Thirty-one percent (3647) of these households reported having children under 18 currently living in the home, with a total of 8878 children living in these homes.

Of the 8,878 children we've identified, 51 (0.57% or 570 per 100,000) met the current CDC definition of CDC according to the answers provided by the adult interviewed. Although we have a small supplemental grant to conduct follow-up telephone interviews with these children to gain a more complete understanding of their symptomatology, we cannot at this time definitely diagnose these children with CFS, as a medical evaluation is necessary for diagnosis. Thus, we can only say that these children have CFS symptoms. This is higher than the 0.0 per 100,000 found in the 2 to 11-year-old group and the 116.4 per 100,000 in the 12 to 17-year-old group found by the CDC to have CFS-like illness in their recent San Francisco study (Dobbins et al., 1996).

Another interesting finding is the race distribution of our sample of children with CFS symptoms. The children identified as having CFS symptoms are 49% Hispanic, 18% African-American, 18% European American, 4% multi-racial, 2% Asian American, and 2% Native American. For comparison, the overall adult sample is 17% Hispanic, 20% African-American, and 55% European-American. Although we cannot say that all these Hispanic children do, in fact, have CFS, these data point to a problem that is definitely in need of further exploration and study. Moreover, these data remind us that this disease does not afflict only middle-age, upper-class, Caucasian individuals.

Let me conclude by emphasizing the need for further research on CFS as it manifests in children and adolescents. It is heartening that the NIH and CDC have begun to recognize the unique concerns and issues of children and adolescents with CFS. Research has begun to answer the questions about this disease. Unfortunately, we are still far from understanding the mechanisms and manifestations of the illness, particularly in young people. Thanks to support from Congress and the public, research funds are being allocated so that we may continue to unravel these mysteries. Thank you for your continuing support.

1. Dobbins JG, Randall B, Reyes M, et al. The prevalence of chronic fatigue illness among adolescents. Paper presented at the AACFS Chronic Fatigue Syndrome Research and Clinical Conference, San Francisco, Oct 1996.
2. Lloyd AR, Hicki I, Boughton CR, et al. Prevalence of chronic fatigue syndrome in an Australian population. Medical Journal of Australia 1990; 153:322-528.