Validation of the Edmonton symptom assessment system in Korean patients with cancer

Context: The Edmonton Symptom Assessment System (ESAS) is a brief, widely adopted, multidimensional questionnaire to evaluate patient-reported symptoms. Objectives: To develop a Korean version of the ESAS (K-ESAS) and to perform a psychometric analysis in Korean patients with advanced cancer. Methods: We tested the K-ESAS in two pilot studies with 15 patients each. We assessed internal consistency, test-retest reliability, and concurrent validity in 163 Korean patients, who completed the K-ESAS along with the Korean versions of the M. D. Anderson Symptom Inventory (K-MDASI) and the Hospital Anxiety and Depression Scale (K-HADS) twice. A total of 38 patients completed the questionnaires again seven days later to assess responsiveness. Results: The K-ESAS scores had good internal consistency, with a Cronbach's alpha coefficient of 0.88, indicating that no questions had undue influence on the score. Pearson correlation coefficients for K-ESAS symptom scores between baseline and after two to four hours ranged from 0.72 (95% CI 0.64-0.79) to 0.87 (95% CI 0.82-0.90), indicating strong test-retest reliability. For concurrent validity, Pearson correlation coefficients between K-ESAS symptom scores and corresponding K-MDASI symptom scores ranged from 0.70 (95% CI 0.62-0.77) to 0.83 (95% CI 0.77-0.87), indicating good concurrent validity. For the K-HADS, concurrent validity was good for anxiety (r = 0.73, 95% CI 0.65-0.79) but moderate for depression (r = 0.4, 95% CI 0.26-0.52). For responsiveness, changes in K-ESAS scores after seven days were moderately correlated with changes in K-MDASI scores but weakly correlated with changes in K-HADS scores. Conclusion: The K-ESAS is a valid and reliable tool for measuring multidimensional symptoms in Korean patients with cancer.