Development and Primary Validation of the Vienna Post-Exertional Malaise Assessment Questionnaire

Background

Post-exertional malaise (PEM) is increasingly understood as a multidimensional deterioration process involving diverse triggers, functional loss, and prolonged recovery. This study developed and initially validated the Vienna Post-Exertional Malaise Assessment Questionnaire (VPEM-AQ), a patient-reported outcome measure assessing PEM manifestations and functional consequences in ME/CFS.

Methods

We conducted a primary psychometric validation study in adults with ME/CFS. The VPEM-AQ assessed crash frequency, exertion thresholds across physical, cognitive, sensory, emotional-social, and orthostatic domains, crash severity, recovery duration, new or additional crash-related symptoms, and pacing behaviour. Analyses included descriptive statistics, floor and ceiling effects, factor analyses, internal consistency, convergent validity with DSQ-PEM and FUNCAP-27, and known-groups validity.

Results

The VPEM-AQ was completed by 1,108 adults; 83.0% female, median age was 46 years (IQR 36–54). The score showed no relevant floor or ceiling effects. Internal consistency was good for the 7-item score (Cronbach’s α = 0.82) and improved in the 6-item version excluding the weaker new-symptoms item (α = 0.87). Confirmatory factor analysis showed mixed fit, indicating that the VPEM-AQ should not be interpreted as a fully homogeneous one-dimensional scale. Convergent validity was supported by correlations with DSQ-PEM (ρ = 0.475; 95% CI 0.425–0.522) and FUNCAP-27 (ρ = −0.680; 95% CI − 0.713 to − 0.643). Known-groups validity was supported across DSQ-PEM quartiles (H = 313.3, p < 0.001) and FUNCAP-27 quartiles (H = 412.5, p < 0.001), although discrimination between the two highest DSQ-PEM quartiles was limited.

Conclusions

The VPEM-AQ showed promising but not definitive initial psychometric properties, particularly for multidomain exertion thresholds. Crash severity and recovery duration remain clinically important but require simpler or diary-based formats before scoring.

Key messages

• The VPEM-AQ is a promising new patient-reported tool to assess multidimensional post-exertional malaise in ME/CFS.

• The VPEM-AQ captures the wide variation of post-exertional malaise in ME/CFS, reflecting differences in triggers, severity, recovery, and functional impact.