The Psychometric Properties and Factor Structure of Persian Version of Edmonton Symptom Assessment Scale in Cancer Patients

CONTEXT: Edmonton Symptom Assessment Scale (ESAS) was developed to assess objective and subjective symptoms in patients with cancer in all stages of their disease. AIM: The aim of the study was to translate and determine the psychometric properties of ESAS in an Iranian population. MATERIALS AND METHODS: The current study was carried out to determine reliability and validity of ESAS using 246 patients with cancer in Imam Khomeini Hospital, Ardabil, Iran. After translating the instrument to Persian, content and face validity, discriminant validity, internal consistency, and test-retest were done to determine psychometric properties of ESAS. Furthermore, the construct validity was determined using confirmatory factor analysis to evaluate factor structure of the tool in two models: single factor and three factor. RESULTS: With regard to goodness of fit indices including comparative fit index, incremental fit index, and normed fit index, factor structure of ESAS was confirmed with one factor and nine items. Because the values of average variance extracted of each dimension were less than the square of correlation coefficients between the three dimensions of ESAS, three-factor model was not confirmed. Discriminant validity was confirmed by finding significant differences between the two groups, patients with good general and critically ill conditions. Cronbach's alpha for the overall ESAS was 0.88, and correlation between test-retest with 4–6 h interval was 0.86 (r = 0.86 P < 0001). CONCLUSIONS: This study showed that Persian version of ESAS with same factor structure mentioned in the original version is an applicable tool for assessing objective and subjective symptoms in Iranian patients with cancer.