Dissecting the nature of post-exertional malaise

Abstract

Background: Post-exertional malaise (PEM) is a defining characteristic of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) but there is insufficient research dissecting the nature of PEM from the patients’ perspective. Methods: A PEM questionnaire administered to 150 ME/CFS patients. It included open-ended questions about triggers, experiences, recovery, and prevention. Responses were re-coded into concise, representative topics. Chi-Square tests of independence were then used to test for differences and relationships between duration of ME/CFS illness (<4 years and >10 years), PEM onset and duration, and gender with PEM trigger, experience, recovery, and prevention. Results: Physical exertion was the most common trigger of PEM. The onset of PEM occurred within minutes after physical exertion compared to within hours after cognitive exertion (<0.05). ME/CFS patients sick for <4 years reported stress as a trigger significantly more often than those sick for >10 years (<0.001). ME/CFS patients sick for <4 years experienced more orthostatic symptoms during PEM than those sick for >10 years. ME/CFS patients sick for >10 years reported using medications to recover from PEM significantly more that those sick for <4 years (<0.01). Pacing and avoiding specific triggers were common approaches to prevent PEM. Conclusions: There are differences in PEM triggers, experiences and recovery based on duration of illness. Asking about PEM is important for diagnosis and to understand how to manage PEM. Given that PEM occurs more quickly after physical versus cognitive exertion, these results should instigate research on the relationship of upright posture, hypoperfusion and PEM.