Abstract:
Objectives: Post-exertional malaise (PEM) is a multidimensional exertion-response pattern involving diverse triggers, variable onset, and prolonged recovery. This study developed and content-validated the Vienna Post-Exertional Malaise (VPEM) Questionnaire, a patient-reported outcome measure assessing functional decline, recovery, crash-associated symptoms, and pacing adaptations in ME/CFS.
Methods: An iterative mixed-methods instrument-development study combined quantitative ratings and qualitative feedback across sequential evaluation cycles. An initial 13-item draft, informed by existing PEM, fatigue, and functional-capacity instruments and consensus literature, was evaluated by individuals with ME/CFS or Post-COVID-19 syndrome (PCS) using Likert ratings, open-ended feedback, and interviews. Quantitative data were summarised descriptively, and qualitative data were analysed using deductive-inductive structuring content analysis. Revisions were documented in revision matrices. The revised instrument was evaluated by an interdisciplinary expert panel using domain-level and item-level ratings of relevance and clarity.
Results: Twelve individuals with ME/CFS and one individual with PCS fulfilling ME/CFS criteria evaluated the questionnaire. Ratings showed high approval for length (92.3%) and terminology (76.9%), while completeness and clarity were more heterogeneous. Qualitative findings identified ambiguities in distinguishing PEM from non-specific fatigue, missing trigger domains, and insufficient representation of intra-individual variability. After revision, the expert panel (n = 11) rated PEM coverage as complete or largely complete (100%) and the multidimensional structure as suitable or very suitable (90.9%). Item-level ratings showed high relevance (S-CVI/Ave = 0.96), whereas clarity ratings were more variable (S-CVI/Ave = 0.82).
Conclusions: The VPEM Questionnaire operationalises PEM as multidimensional post-exertional deterioration. Findings support initial content and face validity, warranting further psychometric validation.
Source: Pimminger T, Ahrens-Schwabe A, Fragner T, Brandl T, Kotzian ST, Wüst RCI, Waldhoer T, Kapan A. Development and initial content validation of the Vienna post-exertional malaise questionnaire: an iterative mixed-methods study. Qual Life Res. 2026 Nov 7;35(12):327. doi: 10.1007/s11136-026-04434-2. PMID: 42998183; PMCID: PMC13744550. https://pmc.ncbi.nlm.nih.gov/articles/PMC13744550/ (Full text)