Over the lifetime of Clinical Child Psychology and Psychiatry, there has been considerable progress in understanding the epidemiology of Chronic Fatigue Syndrome (CFS), also known as myalgic encephalomyelitis (ME) and some progress in testing treatment approaches. Twenty-five years ago, clinicians and researchers did not believe that CFS existed in primary school children, little was known about the experience of children, and there were no randomised controlled trials testing treatment approaches. In this review, major developments in epidemiology, knowledge about clinical presentations and correlates, impact of CFS and treatment approaches will be highlighted. We are clinicians and researchers working in specialist CFS services in the United Kingdom.CFS has been a defined diagnostic entity since 1991 (Sharpe et al., 1991). There are several different diagnostic frameworks for diagnosing CFS (Carruthers et al., 2011;Fukuda et al., 1994;NICE, 2007;Sharpe et al., 1991). All include ongoing, debilitating fatigue which is not secondary to another medical condition or to exertion. Concomitant symptoms include general malaise, headaches, muscle and joint pain, nausea, disrupted sleep, dizziness and cognitive difficulties. Initially, the diagnostic criteria for adults were applied to children and young people. In 2004, the Royal College of Paediatrics and Child Health (RCPCH, 2004) recommended that fatigue lasting > 3 months was sufficient, a shorter duration than is required for adults. This has been reflected in some but not all the diagnostic frameworks. Here, we predominantly draw on evidence from clinical cohorts with a confirmed CFS diagnosis and evidence from general population studies of chronic debilitating fatigue, not necessarily formally assessed and diagnosed CFS.
Changes in epidemiologyTwenty-five years ago, we did not know how common CFS was in teenagers, and whether it even existed in primary school aged children. The evidence base for the prevalence, incidence, and risk factors in paediatric CFS has since developed considerably.A recent systematic review and meta-analysis of prevalence studies found six studies in children and adolescents, with an estimated prevalence of 0.89% although there was considerable