Psychometric evaluation of the Fatigue Severity Scale in patients with major depression.
OBJECTIVE
This study aimed to investigate the psychometric properties of the Fatigue Severity Scale (FSS), a widely used unidimensional fatigue measure, in patients with major depression.


METHODS
Subjects included were 72 patients with major depressive disorder, diagnosed with the DSM-IV based M.I.N.I. 5.0.0., without comorbid fatigue-associated conditions and Hamilton Depression Rating Scale (HDRS) scores ≥ 17 as well as 40 sex- and age-matched healthy controls. The FSS was administered to patients on two time points separated by a 1-week interval and to controls. The vitality subscale of the 36-item Short Form Health Survey (SF-36vit) and a visual analogue fatigue scale (VASF) were also administered.


RESULTS
A total of 79.2% of patients vs. 15% of controls were fatigue cases according to the M.I.N.I. fatigue/energy loss item. The distribution of FSS scores was negatively skewed in the patient group, demonstrating a ceiling effect. The FSS presented satisfactory test-retest reliability (intraclass correlation coefficient 0.993), internal consistency (Cronbach's α coefficient 0.947), concurrent validity (correlations with SF-36vit, VASF and HDRS were -0.52, 0.73 and 0.32, respectively) and discriminative validity between patients and controls. Factor analysis demonstrated a unidimensional structure. The optimal FSS cutoff score for clinically significant fatigue was 5.4 against the presence of fatigue/energy loss according to the M.I.N.I. as a 'gold standard'.


CONCLUSIONS
When administered to patients with major depression, the FSS was shown to have satisfactory psychometric properties with the exception of a ceiling effect, which may pose limitations to its use in this population.
Ferentinos
Panagiotis
P
2nd Department of Psychiatry, Attikon General Hospital, Athens University Medical School, 1 Rimini St, 12462 Athens, Greece. pferentinos@med.uoa.gr
Kontaxakis
Vassilis
V
Havaki-Kontaxaki
Beata
B
Dikeos
Dimitris
D
Lykouras
Lefteris
L
D000293:Adolescent; D000328:Adult; D000368:Aged; D003865:Major Depressive Disorder / Q000150:complications* / Q000503:physiopathology; D005221:Fatigue / Q000503:physiopathology*; D005260:Female; D006115:Greece; D006801:Humans; D008297:Male; D008875:Middle Aged; D010361:Patients / Q000523:psychology*; D011594:Psychometrics; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires / Q000592:standards*; D055815:Young Adult