Is chronic fatigue syndrome in older patients a different disease? -- a clinical cohort study.

Background: Chronic fatigue syndrome (CFS) is a disabling disorder characterised by persistent fatigue with a typical age of diagnosis of 35-50 years. CFS does present in those aged over 50 but whether this is a different disease in older age groups has not been considered. Therefore, we performed a clinical cohort study to examine and differentiate the clinical and autonomic features in CFS patients aged over 50.

Design: A total of 179 Fukuda diagnosed CFS patients were recruited, and 25 older CFS patients (50 + years) were matched case by case for gender and length of history to 25 younger CFS patients (16-29 years). A range of symptomatic-based questionnaires were used in addition to heart rate variability and baroreceptor sensitivity to assess autonomic function.

Results: Chronic fatigue syndrome can present for the first time in an older population. Older CFS patients demonstrate increased fatigue (Fatigue impact scale; 85 ± 33 vs. 107 ± 27, P = 0·02) (Chalder fatigue scale; 9 ± 3 vs. 11 ± 1, P = 0·002) and caseness for depression (Hospital Anxiety and Depression scale; 7 ± 3 vs. 10 ± 4; P = 0·005). There is a greater autonomic dysfunction in older CFS patients, with reduced parasympathetic function (HFnu; 49·1 ± 18 vs. 36·2 ± 18, P = 0·01, RR30 : 15; ± , P = 0·02) and increased sympathetic function (LFnu; 51·5 ± 17 vs. 63·8 ± 18, P = 0·01). Baroreflex sensitivity was substantially reduced (BRS; 19·7 ± 12 vs. 9·9 ± 5, P = 0·0004), and left ventricular ejection time prolonged (LVET; 274·6 ± 16 vs. 285·8 ± 9, P = 0·004).

Conclusions: Older CFS patients demonstrate a disease phenotype very different from younger patients. The combination of differing underlying pathogenic mechanisms and the physiological aspects of ageing result in a greater disease impact in older CFS patients.