Psychometric Properties of a Persian Version of the Chalder Fatigue Scale

Fatigue refers to a lack of energy that makes it challenging to initiate or maintain voluntary activities. The Chalder Fatigue Scale (CFS) is a tool designed to assess the severity of fatigue. Studies indicate that it has strong validity and internal reliability, measuring both the mental and physical aspects of fatigue. We aimed to translate this questionnaire and to evaluate its psychometric properties in Iran.

The translation process adhered to guidelines for cross-cultural adaptation of self-report measures. This cross-sectional study included 70 participants. The reliability of the CFS was evaluated through internal consistency and test-retest reliability. To determine test-retest reliability, each participant completed the scale twice, with a two-week interval between assessments. Construct validity was assessed using factor analysis and principal component analysis. For content validity, a form was completed by 15 experts to evaluate the relevance and necessity of the items, calculating both the Content Validity Index (CVI) and the Content Validity Ratio (CVR).

The average age of the participants was 38 years, with a standard deviation of 8.52. Among the participants, 22 (31.4%) were male. Content validity analysis yielded a CVI of 0.88, indicating acceptable relevance, and a CVR of 0.81, demonstrating good content validity. Factor analysis identified a two-factor solution. The Cronbach's alpha coefficient for the CFS was 0.89. The Intraclass Correlation Coefficient for the CFS was 0.79 (95% confidence interval: 0.66-0.87, P < 0.001), reflecting good test-retest reliability.

The results indicate that the CFS is a reliable and valid tool for assessing fatigue, making it suitable for use in both research and clinical environments in Iran.