CONTEXT: Unexplained fatigue states are prevalent, with uncertain diagnostic boundaries.
OBJECTIVE: Patients with fatigue-related illnesses were investigated by questionnaire and a novel semistructured interview to identify discriminatory features.
METHODS: Cross-sectional samples of women from specialist practices with chronic fatigue syndrome (n = 20), postcancer fatigue (PCF; n = 20), or major depression (n = 16) were recruited. Additionally, two longitudinal samples were studied: women with fatigue associated with acute infection who subsequently developed postinfective fatigue syndrome (n = 20) or recovered uneventfully (n = 21), and women undergoing adjuvant therapy for breast cancer experiencing treatment-related fatigue who subsequently developed PCF (n = 16) or recovered uneventfully (n = 16). Patients completed self-report questionnaires, and trained interviewers applied the Semi-structured Clinical Interview for Neurasthenia. The receiver operating characteristics curves of the interview were measured against clinician-designated diagnoses. Cluster analyses were performed to empirically partition participants by symptom characteristics.
RESULTS: The interview had good internal consistency (Cronbach α “fatigue” = .83), and diagnostic sensitivity and specificity for chronic fatigue syndrome (100% and 83%) and major depression (100% and 72%), with reasonable parameters for PCF (72% and 58%). Empirical clustering by “fatigue” or “neurocognitive difficulties” items allocated most patients to one group, whereas “mood disturbance” items correctly classified patients with depression only.
CONCLUSIONS: The Semi-structured Clinical Interview for Neurasthenia offers reliable diagnostic use in assessing fatigue-related conditions. The symptom domains of fatigue and neurocognitive difficulties are shared across medical and psychiatric boundaries, whereas symptoms of depression such as anhedonia are distinguishing.
Characterization of Fatigue States in Medicine and Psychiatry by Structured Interview, by BK Bennett in Psychosom Med. 2014 May 6. [Epub ahead of print]