Today, there are many case definitions for ME, CFS or their combination – around 20 according to a 2014 review, and 21 if we include the new SEID definition from the Institute of Medicine. Each is different to a greater or lesser degree, and all are based on collections of non-specific symptoms shared with other illnesses. Diagnosis using any one of them remains a ‘diagnosis of exclusion’, which means that more recognised illnesses with similar symptoms need to be excluded before a final diagnosis of, say, ME/CFS can be made.

Prof. Leonard Jason of DePaul University in Chicago has been at the forefront of research into the development and application of diagnostic criteria for ME/CFS for many years. In 2010, he developed a standard questionnaire, The DePaul Symptom Questionnaire, to assess core symptoms of ME/CFS. The aim was to assist diagnosis by ensuring that symptoms are assessed in a consistent way across different clinical settings. Since then, the questionnaire has been refined, and it now comes in a format which scores symptoms and SF-36 quality of life data, and produces a ‘diagnosis’ based on several of the more common definitions of ME, CFS and ME/CFS.

The DePaul Symptom Questionnaire has been made available to other research groups, and is currently being trialled (operationally tested) on existing groups of clinically assessed ME/CFS patients. One of the most comprehensive of these is the ‘well-characterised’ ME Research UK cohort at the University of Newcastle, containing a large volume of clinical, autonomic and symptom data on several hundred people with the illness. In 2012, ME Research UK provided seed-corn funding to Prof Julia Newton of the University of Newcastle to help evaluate the questionnaire’ using the data in the ME Research UK cohort (see project page).

This new study by Prof Jason, published in International Journal of Psychology and Behavioral Sciences (abstract below), is the latest in his series of reports emanating from this work. It compares the DePaul Symptom Questionnaire and SF-36 quality of life data in two distinct groups – 83 patients from the ME Research UK cohort in the UK and 162 from a database at DePaul University in the USA.

There were many similarities between the US and UK sample groups, as we might expect. For example, more than 80% were women in each group, more than 97% were white, and more than 50% were married or living with a partner. And similar numbers said that their illness began after an infection (70% and 65% in the US and UK samples) or surgery (12% and 13%). However, the US sample was older on average (56 years) than the UK sample (49 years), and had a higher proportion of people on disability benefits (55% compared with 35% in the UK). A far greater proportion of the US sample had previously been treated for multiple chemical sensitivities (20% versus 5%) or fibromyalgia (43% versus 30%).

The groups also differed in their perceptions of the causes of illness. In the US sample, 95% thought that the origin of their illness was definitely or mainly physical, whereas the equivalent figure in the UK was 79%. Also, 19% of the UK sample thought the cause of their illness was “equally physical and psychological” compared with 5% in the US. When the authors looked more closely at the UK sample, they found that the patients endorsing possible psychological influences were more likely to have been previously diagnosed with or treated for depression. As they speculate, “if physicians believe the cause of the illness is more psychological than physical, they may be more likely to diagnose an individual with a psychological illness, such as depression. The perception of the illness by the physicians may then also influence the beliefs of the patients, which may account for the difference in belief of illness cause between the US and the UK samples.”

Overall, physical functioning and general health were poor in the US and UK cohorts, as expected in groups of ME/CFS patients. However, greater numbers in the UK cohort reported muscle pain (31% versus 21% in the US sample), joint pain (33% versus 15%), and problems with memory/concentration (31% versus 15%). The UK cohort also scored significantly worse than the US cohort on the SF36 quality of life subscales for self-reported ‘mental health’ and emotional functioning. Prof Jason and colleagues speculate that differences in the healthcare system of the two countries might account for at least some of these discrepancies. For instance, the UK offers universal free health care on a highly regulated basis, and it may be that assessments for ME/CFS are offered more often to people with more severe symptoms.

We have to be cautious in interpreting these results, of course, as recruitment methods differed between the samples. The US cohort consisted of people who initially self-reported a diagnosis that was confirmed by their answers on the DePaul Symptom Questionnaire, while the UK sample was collected from patients referred to a hospital clinic by their GPs. These different ways of recruiting could well have resulted in qualitatively different groups of patients with very different clinical characteristics and experiences of clinical care. However, as the authors point out, the results may, in fact, point up real differences in the characteristics and experience of ME/CFS on both sides of the pond.

Funding
The authors appreciate the financial assistance provided by the National Institute of Allergy and Infectious Diseases
(grant number AI055735) and ME Research UK.

Reference
Zdunek M, Jason LA, Evans M, Jantke R, Newton JL. A cross cultural comparison of disability and symptomatology associated with cfs. International Journal of Psychology and Behavioral Sciences 2015; 5(2): 98-107. Read more (full text).

Abstract
Few studies have compared symptomatology and functional differences experienced by patients with chronic fatigue syndrome (CFS) across cultures. The current study compared patients with CFS from the United States (US) to those from the United Kingdom (UK) across areas of functioning, symptomatology, and illness onset characteristics. Individuals in each sample met criteria for CFS as defined by Fukuda et al. (1994). These samples were compared on two measures of disability and impairment, the DePaul Symptom Questionnarie (DSQ) and the Medical outcomes study 36-item short-form health survey (SF-36).

Results revealed that the UK sample was significantly more impaired in terms of mental health and role emotional functioning, as well as specific symptoms of pain, neurocognitive difficulties, and immune manifestations. In addition, the UK sample was more likely to be working rather than on disability. Individuals in the US sample reported more difficulties falling asleep, more frequently reported experiencing a sudden illness onset (within 24 hours), and more often reported that the cause of illness was primarily due to physical causes.

These findings suggest that there may be important differences in illness characteristics across individuals with CFS in the US and the UK, and this has implications for the comparability of research findings across these two countries.

Other recently published studies using the DePaul Symptom Questionnaire
Jason LA, Evans M, Brown A, Sunnquist M, Newton JL. Chronic fatigue syndrome versus sudden onset myalgic encephalomyelitis. J Prev Interv Community, 2015; 43(1): 62-77. Supported by the NIAID and ME Research UK. Read more
Jason LA, Sunnquist M, Brown A, Evans M, Newton JL. Are Myalgic Encephalomyelitis and chronic fatigue syndrome different illnesses? A preliminary analysis. J Health Psychol 2014 Feb 7 . Supported by the NIAID and ME Research UK. Read more
Jason LA, Brown A, Evans M, Sunnquist M, Newton JL (2013). Contrasting chronic fatigue syndrome versus myalgic encephalomyelitis/chronic fatigue syndrome. Fatigue: Biomedicine, Health & Behavior 2013; 1(3): 168-183. Supported by the NIAID and ME Research UK. Read more

Picture credit
Topography of the UK – see more
Topography of the USA – see more