Psychometric Testing of the Mandarin Chinese Version of the Fatigue Severity Scale (CFSS) in Patients with Major Depressive Disorder

Wang, Mei-Yeh

Background

Fatigue is a symptom that is highly prevalent in patients with major depressive disorder (MDD) and as one of the most common residual symptoms that occurs in MDD.

Aim

The aim of the present study was to examine the psychometric properties of the Mandarin Chinese version of the Fatigue Severity Scale (CFSS) in MDD patients.

Methods

A total of 179 participants (101 MDD patients and 78 healthy controls) were included. The MDD patients were recruited from an outpatient department of psychiatry and currently under antidepressant treatment. The psychiatric diagnosis was confirmed by a psychiatrist based on the diagnostic criteria for major depression stipulated in the DSM-IV. The correlations with a visual analogue scale for fatigue (VASF), the Chinese versions of the Beck Depression Inventory (CBDI), the CBDI loss of energy item, CBDI fatigue item, and the vital subscale of the Short Form-36 Health Survey (SF36-vit) were used to assess the concurrent validity of the CFSS. To measure the discriminate validity of CFSS, we examined the differences in CFSS scores between MDD patients and healthy controls. The level of agreement between CFSS and VASF was assessed using Bland-Altman analysis.

Results

Reliability analysis revealed that CFSS had satisfactory internal consistency (Cronbach's alpha coefficient = 0.93). The significant item-item correlation (r=0.34-0.82, all p<0.001) and item-scale correlation (r=0.41-0.83, all p<0.001) were observed. The correlation coefficients among the CFSS and VASF, CBDI, and CBDI-loss of energy item, and BDI -fatigue item were 0.66 (p <0.001), 0.59 (p <0.001), 0.53 (p <0.001), and 0.57 (p <0.001), respectively. The CFSS also negatively correlated with the SF36-vit (r=-0.59, p <0.001). The CFSS scores were significantly different between MDD patients and healthy controls (p<0.001). Most of the difference between CFSS and VASF lied between the limits of agreement as seen in the Bland-Altman plot. The Bland-Altman plot also revealed that no specific pattern of differences between CFSS and VASF was observed

Conclusions

The 9-item scale presented satisfactory internal consistency, concurrent and discriminated validity. The agreement between fatigue severity assessed by CFSS and VASF was acceptable. This preliminary validation study of the CFSS proved that it is a valid and reliable Mandarin-language instrument for measuring fatigue severity in MDD patients.