Severe Versus Moderate Criteria for the New Pediatric Case Definition for ME/CFS

The Pediatric Case Definition for ME/CFS also diagnoses children and adolescents with subtype variations for ME/CFS for those who experience idiopathic chronic fatigue. Two of the children who had been referred as having ME/CFS were classified within this group. For example, one subtype variation is Atypical ME/CFS, which is defined as 3 or more months of fatigue, but having at least two classic ME/CFS symptoms. Accordingly, 2 children met the criteria for Atypical ME/CFS illness. Further, a child could be classified as having ME/CFS in remission, if the child met full symptom criteria at one time but was not experiencing full symptomology at the time of the study. To qualify for inclusion to this group, children must not currently meet either the Severe, Moderate, or Atypical criteria, and must have 0 or 1 classic ME/CFS symptoms, and their symptoms need to be reported as improving over time. One of the participants were categorized as experiencing ME/CFS in remission, as this participant was not currently meeting full criteria and reported that the long standing condition had improved dramatically at the time of evaluation.

Because of small sample sizes, we did not include ME/CFS-like, atypical ME/CFS, those In Remission, and ME/CFS-like.

In addition, as one part of the ME/CFS Severe criteria, a child needed to respond yes to the question: “Need to limit activity”. As another part of the original Fatigue criteria, to meet Severe ME/CFS criteria, a child would need to indicate that with rest, all of their fatigue would not go away. A child could receive a Moderate ME/CFS diagnosis, and indicate that with rest, some or all of their fatigue went away. We did not find these items differentiating the Severe or Moderate ME/CFS groups, and the original Fatigue question was sufficient to differentiate the Severe or Moderate ME/CFS groups from the Controls. We no longer require these two additional questions in meeting criteria for ME/CFS.

An additional requirement for post-exertional malaise, in order to meet the original pediatric case definition of ME/CFS, involved the question: “how does being physically active make you feel for the rest of the day?” A response of “much more tired than usual” or “more tired than usual” was required, but this question was not needed to differentiate the Moderate from Severe ME/CFS diagnosis, and the original post-exertional malaise item was sufficient to differentiate the Moderate and Severe ME/CFS groups from the Controls. We therefore only required the original post-exertional malaise question to met the ME/CFS requirement.