Post Exertional Symptoms Are Similar in Male and Female Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

BACKGROUND: ME/CFS is an illness which is exclusively diagnosed through reported symptoms. Most people affected by myalgic encephalomyelitis/ chronic fatigue syndrome (ME/CFS) remain undiagnosed. A hallmark feature of ME/CFS is post-exertional malaise (PEM), the worsening of symptoms following exertion. It is unknown whether PEM presents differently based on sex. PURPOSE: Compare PEM symptoms reported by males and females with ME/CFS after cardiopulmonary exercise testing (CPET). METHODS: Males and females described symptoms using an open-ended questionnaire during and following two days of exertion. Exertion was standardized by using objective criteria for maximal exertion. Symptoms were then classified into 20 categories. Fisher's exact test was used to compare the percentages of men versus women endorsing each symptom category for each time point while the Mann-Whitney U test was used to compare the mean number of symptom categories reported and time needed to recover from the CPETs. A p< 0.05 was considered significant. RESULTS: During and following the CPETs, 25.6% more women reported gastrointestinal disturbances compared to men (34.3% vs. 8.7%, p=0.02). Conversely, 24 hours after the first CPET, 15.7% more men reported light-headedness (21.7% vs. 6.0%, p=0.04). Otherwise, men and women recounted similar symptoms. Immediately and 24 hours after the 2nd CPET, women endorsed slightly more symptom categories than men (3.5±1.8 vs. 2.6±1.5 and 3.7±2.1 vs. 2.8±1.7, respectively, both p=0.04). Fifty-two percent of women and forty-five percent of men took more than a week to recover (p=0.56). The remaining participants took 4.9 ± 2.1 days and 4.8 ± 1.8 days, respectively, to return to their baseline (p=0.58). CONCLUSIONS: Except for gut symptoms and light-headedness, men and women with ME/CFS experienced similar symptoms during PEM. There were no differences in recovery time. Practitioners should ask about these two symptoms when attempting to identify PEM.