Fatigue is a highly
prevalent symptom in populations with chronic illness. It has
a complex phenomenology, relates to numerous potential etiologies,
and accompanies a broad array of physical and psychological
comorbidities (Portenoy
and Miaskowski, 1998). When chronic, it can profoundly
undermine quality of life.
The complexities
involved in the definition of fatigue and its assessment in
the medically ill may have contributed to the paucity of scientific
investigations focused on the nature of this problem and its
management in diverse clinical settings. Although improved methodologies
to measure fatigue have led to studies of fatigue epidemiology,
particularly in populations with cancer, there are very few
studies that illuminate pathophysiology or establish the effectiveness
of therapies.
The increasing epidemiologic
data, combined with the progress that has been made in fatigue
measurement, have primed the scientific community for a range
of new inquiries. In many ways, fatigue research can be likened
to pain research a quarter century ago, when recognition of
the clinical problem had evolved, measurement approaches were
available, and new methodologies for intervention trials were
being explored. Indeed, the lessons of pain research discussed
by Max
are useful background for this discussion of fatigue-related
research.