Measuring fatigue in medically unwell and distressed patients

Fatigue is now recognized as part of the phenotype of an increasing number of physical disorders and may be caused by a number of direct and indirect mechanisms. Fatigue may have a significant impact on health-related quality of life (HRQL) and therefore there has been increased interest in its measurement. Fatigue may be measured as part of a generic HRQL assessment scale (e.g. the SF-36) or symptom specific rating scales. A large number of these scales have recently been developed although the majority of these have been used only in a limited range of situations. Much research has concentrated on cancer-related fatigue, which is one of the commonest and most distressing symptoms experienced by patients with malignancies. At least eight separate fatigue assessment scales have been designed for use in such patients, although several of these have been reported in single studies only. Fatigue has been studied to a lesser extent in neurological, liver and cardio-respiratory disorders and disease specific scales have been developed. Further development work is necessary to establish the generalisability of these scales so that they may be incorporated into routine clinical assessment and the therapeutic trials.