A medical definition of fatigue in multiple sclerosis.
BACKGROUND
The symptom of fatigue has been described in a variety of ways but absence of a single taxonomy may be hindering research into this prevalent symptom.


OBJECTIVE
To define the symptom of fatigue, as experienced by patients with multiple sclerosis (MS), in terms of a common framework, typical of a medical history.


METHODS
Qualitative phase followed by cross-sectional questionnaire survey.


METHODS
Forty patients, with clinically definite MS, underwent semi-structured interviews which were analysed within a common framework of: experience (with derived themes of motor, cognitive, somatic/energy, sleep, other features) cadence (i.e. short-term variability), chronicity, precipitating and aggravating factors, relieving factors, severity and associated features. The prevalence of each feature of fatigue, emergent from the interviews, was subsequently determined by questionnaire survey of a further 635 MS patients.


RESULTS
Despite variance across patients, fatigue could be described within the derived themes and framework. Nearly all themes were endorsed by the majority of questionnaire respondents. In summary, fatigue could be defined as reversible motor and cognitive impairment, with reduced motivation and desire to rest. It could appear spontaneously or may be brought on by mental or physical activity, humidity, acute infection and food ingestion. It was relieved by daytime sleep or rest without sleep. It could occur at any time but was usually worse in the afternoon.


CONCLUSIONS
A framework, not only derived from patient experience but also meaningful in a medical context, was shown to be capable of describing fatigue in a large cross-section of MS patients. The definition may facilitate inter-disease comparison of fatigue as well as physiological enquiry.
Mills
R J
RJ
Department of Neurology, The Walton Centre for Neurology and Neurosurgery, Lower Lane, Fazakerley, Liverpool, UK. rjm@crazydiamond.co.uk
Young
C A
CA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D005221:Fatigue / Q000175:diagnosis* / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D005222:Mental Fatigue / Q000175:diagnosis* / Q000209:etiology; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000150:complications*; D009626:Terminology as Topic