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.