Researchers, including Associate Prof. Rob Wust, who is working on research funded by ME Research UK, have developed a new questionnaire to assess post exertional malaise (PEM). Notably, PEM is often referred to as the cardinal feature of ME/CFS in which symptoms worsen after any type of exertion including physical, mental, social, or cognitive exertion.

The questionnaire – the Vienna Post-Exertional Malaise (VPEM) Questionnaire – was initially developed by the research team based on several pre-exiting tools that are commonly used in ME/CFS research, including:

• The Depaul Symptom Questionnaire for PEM (DSQ-PEM).
• The Chalder Fatigue Questionnaire (also known as the Chalder Fatigue Scale) which measures physical and mental fatigue.
• The CDC symptom inventory, which measures a range of symptoms associated with ‘chronic fatigue syndrome’.
• FUNCAP-2712, which is a tool used to measure functional capacity in individuals with ME/CFS.

The researchers explain that this initial draft, written in German, included 13 questions which aimed to assess four key dimensions of PEM: ‘triggers and contextual factors, ‘symptom manifestation’, ‘functional limitations in daily life’, and ‘temporal dynamics, including onset and recovery patterns’.

This initial draft was then revised and reviewed in a number of stages, incorporating feedback from those with lived experience of ME/CFS, and from a group of ‘experts’ which comprised of different health professionals.

Stage 1: 13 people with ME/CFS, including one with long COVID who met ME/CFS criteria, provided feedback on the questionnaire. At this stage, participants said the first draft did not fully reflect their experiences and could confuse PEM with general tiredness.

Importantly, their feedback helped the team:

• Use clearer, less stigmatising language.
• Include triggers such as light, sound, being upright and emotional excitement.
• Reflect changes in crashes and recovery.
• Recognise that fewer crashes may reflect careful activity limits, not milder illness.

Stage 2: Once theteam had incorporated the feedback from stage 1, the revised questionnaire was reviewed by a panel of eleven health and rehabilitation experts. At this stage, the panel “supported the overall structure of the instrument, particularly the multidimensional assessment of PEM, the proposed score weighting, and the separate assessment of crash severity and recovery duration”. The questionnaire was once again refined and the latest version translated from German to English.

Stage 3: During this stage, an online version of the questionnaire was tested by five people with ME/CFS, importantly these individuals did not take part in stage 1. Findings from this stage indicated:

• No major problems with comprehension.
• Two technical and presentational problems including issues with navigation and the burden of scrolling.

Stage 4: Final revisions were made based on the comments in stage 3, and the questionnaire is included as supplementary material (file S3) in the published article.

What are the limitations of the study?

As noted by the research team, limitations include:

• The group of people with lived experience was small and may not reflect everyone’s experiences.
• Those with lived experience helped revise the questions but were not involved from the start.
• Some relevant ‘experts’ were missing, such as those with expertise development of questionnaires in the field.
• Not all final changes were tested.

Takeaway message

The questionnaire is a promising early step, not a fully tested tool. Larger studies need to check its reliability, improve unclear questions and work out what its scores mean. Notably, the VPEM Questionnaire is intended to add to existing tools, not replace them.