Health-related quality of life and history of stressors in myalgic encephalomyelitis/chronic fatigue syndrome patients
Chronic fatigue (CF) is a combination of minimum of 4 of 8 symptoms. Myalgic encephalomyelitis chronic fatigue syndrome (ME/CFS) is a common debilitating disorder associated with an intense fatigue, a reduced physical activity, and an impaired quality of life.
There is no established biological marker which can be helpful in this syndrome. The etiology is unknown and its pathogenesis appears to be multifactorial. Various factors, including intense physical activity, severe infection and emotional stress are reported in the medical history of ME/CFS patients which raises the question whether any physiological and biological abnormalities usually found in these patients could be indicative of the etiology and/or quality-of-life impairment. A study was conducted to check the alteration or association of the biomarkers for chronic fatigue syndrome. Total 36 patients and 11 matched healthy controls were recruited. The following variables that appeared to address common symptoms of ME/CFS were studied:
- Muscle Fatigue during exercise has also been investigated by monitoring the compound muscle action potential.
- The excessive oxidative stress response to exercise was measured via two plasma markers: thiobarbituric acid reactive substances (TBARS); Reduced ascorbic acid (RAA).
- A potential inflammatory component was addressed via the expression of CD26 on peripheral blood mono nuclear cells.
- Quality-of-life impairment was assessed using London Handicap Scale (LHS) and Medical Outcome Study Short Form-36.
The medical history of each patient was included as the presence of stressors such as intense sports practice. Severe acute infection and/or severe emotional stress was also documented.
It was analysed that there were differences between cases and controls with the regard to three biological variables: Post-exercise M wave, TBARS variations and CD26 expression at rest. Abnormalities in the biomarkers associated with health-related quality of life: LHS score was negatively correlated with the exercise-induced TBARS increase and positively correlated with the CD26 expression while the pain component of SF-36 was negatively correlated with CD26 expression. The TBARS increase and M-wave decrease were the highest and CD26 expression level was lowest in patients who had been submitted to infectious stressors.
After discussion, it was observed that ME/CFS patients, severe alterations of the muscle excitability, redox status and CD26 expression level are related with a marked impairment of quality of life. It wa concluded that the simultaneous monitoring of muscle function, redox response and CD26 expression could contribute together with the health status scales to identify the ME/CFS and to assess its severity. These results were also helped to distinguish the ME/CFS from fibromyalgia because the CD26 activity on PBMC increased in fibromyalgia whereas it was decreased in CFS patients.