**1. Introduction**

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex multisystem disorder that is characterised by a range of symptoms that can fluctuate in severity and change over time. These symptoms include post-exertional malaise, incapacitating fatigue that is not alleviated by rest, cognitive dysfunction, sleep disturbances, and muscle pain, while the condition can cause severe diminution in functioning and in quality of life [1].

It is estimated that there are around two million people with ME/CFS in the European Union and the United Kingdom combined, with an economic impact in the region of €40 billion per annum [2]. However, there are considerable difficulties in determining accurate prevalence and cost estimates, for a number of reasons. These include differences in case definitions, lack of empirical information in much of Europe about incidence and prevalence, natural variation between populations in, for example, the proportion of severely affected people, the heterogeneity of national economies and health care systems and, perhaps most importantly, the unwillingness of many doctors, particularly in primary care, either to recognise the condition as a genuine clinical entity or to diagnose it [2,3].

A recent literature review, covering studies from a wide variety of geographical locations world-wide over a 14-year period, found that between a third and a half of general practitioners (GPs) were unwilling to recognise or diagnose ME/CFS, that a similar proportion of patients were dissatisfied with the quality of primary care they had received, and that these proportions varied little over time [4]. In order to investigate this further, and to assess how knowledge and understanding of ME/CFS is perceived by experts in the condition across Europe, we conducted a survey of participants in the European ME/CFS Research Network (EUROMENE) project. EUROMENE was established to promote collaborative research on ME/CFS across Europe and is currently in receipt of EU funding from the COST Association (COST Action 15111) to support network activities. The aims of EUROMENE include reviewing the current state of the art and identifying gaps in knowledge about ME/CFS.

#### **2. Materials and Methods**

A survey questionnaire was sent to national representatives and members of the EUROMENE Core Group and Management Committee in September 2020—see Supplementary Materials. The questionnaire included a number of separate questions relating to: (i) the existence of GP patient lists and national guidance on treatment pathways; (ii) percentages of people with ME/CFS undiagnosed and presenting to a GP; (iii) percentages of GPs recognising, confident to diagnose, and confident to manage ME/CFS; (iv) percentages of patients diagnosed by GP, referred by GP to specialist care, and self-referring to specialist services; and (v) views on needs for teaching, training, reference literature, and referral centres. Responses to these questions were collated and summarized based on the numbers and percentages of respondents selecting each available option and these summary statistics were then used to generate a range of charts to clearly illustrate our main findings. Where options given in questions were in the form of percentages (e.g., 20–40%), weighted averages were calculated assuming the mid-points of the presented percentage ranges.

The questionnaire also included four questions seeking free text responses. The first such question sought purely factual information concerning the existence or otherwise of official guidance in respondents' countries on the managemen<sup>t</sup> of ME/CFS. The other three questions requested opinions on what constitutes specialist care in respondents' countries, ways to increase knowledge and understanding among GPs, and other comments. The responses to these three questions were analysed using thematic analysis [5].
