Other Elements
in Fatigue Assessment
In some studies,
the desire to distinguish among different types of fatigue,
or specifically assess the varied qualities, might be compelling
enough to justify ancillary measurements. For example, a study
that evaluated changes in sleep patterns among fatigued patients
who were undergoing radiation therapy used a noninvasive technique
of wrist actigraphy to measure hours of sleep, sleep efficiency,
and number of awakenings (Richardson,
1998). Studies of therapies for fatigue that could
have strong effects on cognitive dysfunction, such as a new
psychostimulant, might justify the addition of a neuropsychological
assessment as a secondary outcome. Although simple bedside measures
of visual and auditory memory, reaction time and concentration,
are readily available, the development of new and efficient
research designs may require input from a neuropsychologist
skilled in these assessments.
There are additional,
objective tests that have been used in some studies as proxy
measures for fatigue, or perhaps more valuably, as ancillary
measures that can provide complementary information about the
status of a population or the response to an intervention. For
example, a randomized trial of an exercise program in women
with fatigue following radiotherapy (Mock
et al., 1997) incorporated a 12-minute walk test,
in which the distance in feet that can be traveled in 12 minutes
is measured (Larson
et al., 1996). This type of test correlates highly
with results from laboratory measurements of oxygen consumption
during exercise (McGavin
et al., 1976), which could also be used as such an
ancillary measure.