Myalgic encephalomyelitis/chronic fatigue syndrome has been a controversial diagnosis, resulting in tensions between patients and professionals providing them with care.
A major constraint limiting progress has been the lack of a ‘gold standard’ for diagnosis; with a number of imperfect clinical and research criteria used, each defining different, though overlapping, groups of people with myalgic encephalomyelitis or chronic fatigue syndrome.
We review basic epidemiological concepts to illustrate how the use of more specific and restrictive case definitions could improve research validity and drive progress in the field by reducing selection bias caused by diagnostic misclassification.
[After highlighting the danger in generalising the results of studies using patients with unspecific ‘chronic fatigue’ (which could include people with a range of diagnoses, including mental health conditions) to people with ME/CFS, and proposing that strict selection criteria are used in research trials, the Biobank team go on to recommend specialist services do the opposite and accept a broader range of patients:]
Priorities for clinical practice
Nevertheless, it is important to distinguish research from clinical practice. While the former should focus on better definition of disease status, sub-groups and the trialling of preventative and treatment interventions, the main role of the clinician is to provide the best care and support to their patients, irrespective of a diagnosis or lack of it. Therefore, clinical services should be open to people with a broader range of conditions, presenting with, for example chronic fatigue.
Historically, patients accepted by ME/CFS Specialist Services in the United Kingdom have often been required to meet the centers for disease control and prevention (CDC)-1994 criteria (Fukuda et al., 1994) or even broader case criteria (NICE, 2007). We propose that criteria such as the Institute of Medicine (Institute of Medicine, 2015) or the CDC-1994 could still be used as a guide for primary care professionals to refer patients to Specialist Services, provided an adequate workout of cases conducted in primary care to enable the practitioner to suspect a diagnosis of ME/CFS. This could be the case until we have a better understanding of ME/CFS and are in a position to diagnose reliably and offer specific treatments. It is also important to acknowledge that many with chronic fatigue currently referred to ME/CFS specialist services would benefit from alternative care pathways, avoiding overloading already stretched services. This is particularly important for those with an alternative diagnosis explaining their symptoms, including some chronic medical and psychiatric diseases. It has been suggested that between 40 and 64 per cent of cases referred to CFS Specialist services do not meet diagnostic criteria for CFS, so robust referral procedures need to be established (Devasahayam et al., 2012; Newton et al., 2010).
How have selection bias and disease misclassification undermined the validity of myalgic encephalomyelitis/chronic fatigue syndrome studies? by Luis Nacul, Eliana M Lacerda, Caroline C Kingdon, Hayley Curran, Erinna W Bowman in Journal of Health Psychology [Published March 1, 2017]