Fatigue Research Today is a free monthly online journal that collates and summarizes the latest research about Fatigue, including details on chronic fatigue syndrome, exhaustion, causes, diagnosis.

A predictive model for fatigue and its etiologic associations in primary biliary cirrhosis.

Newton JL, Pairman J, Sutcliffe K, Wilton K, Jones DE

Liver Research Group, Institute of Cellular Medicine, Newcastle University, United Kingdom.

BACKGROUND & AIMS: Excessive day-time somnolence and autonomic dysfunction are biological processes prevalent in Primary Biliary Cirrhosis (PBC) that associate with fatigue. Here we explore how these biological associates inter-relate, and their cumulative impact upon typical clinical cohorts. METHODS: A predictive model for daytime hypersomnolence (Epworth Sleepiness Scale (ESS)) and autonomic dysfunction (Orthostatic Grading Scale (OGS)) was developed in a derivation cohort (n=124) and subsequently validated in a second cohort (n=114). Subjects also completed the disease specific quality of life tool, the PBC-40. RESULTS: A composite predictive criterion (presence of either ESS > or =10 or OGS > or =4) for the presence of fatigue in PBC patients had a sensitivity of 0.71 (95% confidence intervals 0.59-0.81) and specificity 0.8 (0.67-0.9) (positive predictive value (PV); 0.84 (0.72-0.92), negative PV; 0.66 (0.53-0.78) for moderate or severe fatigue). Ninety-seven percent of severely fatigued patients (0% of non-fatigued) met the aetiology predictive criterion (chi(2) 49.6, P<.0001). Expression of both significant daytime somnolence and autonomic dysfunction was not associated with more severe fatigue, suggesting that there is a threshold effect for fatigue in PBC. When applied to a second independent cohort, the composite criterion retained strongly significant predictive value for fatigue. CONCLUSIONS: A significant proportion of fatigue in PBC associates with one or both of autonomic dysfunction (OGS > or =4) and sleep disturbance (ESS > or =10). Those meeting both ESS and OGS criteria were not more severe fatigued than those meeting the diagnostic criterion for either OGS or ESS alone. A threshold effect for fatigue has implications for potential therapeutic interventions.

Published 1 February 2008 in Clin Gastroenterol Hepatol, 6(2): 228-33.
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