Validation of Korean Version of the COmprehensive Score for financial Toxicity (COST) Among Breast Cancer Survivors

Shim, S., Kang, D., Kim, N., Han, G., Lim, J., Kim, H., Park, J., Lee, M., Lee, J. E., Kim, S. W., Yu, J., Chae, B. J., Ryu, J. M., Nam, S. J., Lee, S. K., Cho, J.

PURPOSE: Little is known about the impact of financial toxicity in disease-free breast cancer survivors. We aim to validate the COST in Korean (COST-K) and evaluate financial toxicity among disease-free breast cancer survivors. MATERIALS AND METHODS: We conducted linguistic validation following a standardized methodology recommended by FACITtrans. For psychometric validation, we conducted a cross-sectional survey with 4,297 disease-free breast cancer survivors at a tertiary hospital in Seoul, Korea between November 2018 and April 2019. Survivors were asked to complete the COST-K and EORTC QLQ-C30 questionnaires. The test-retest reliability, internal consistency, and validity of the COST-K were assessed using standard scale construction techniques. RESULTS: The COST-K demonstrated good internal consistency, with a Cronbach’s α of 0.81. The test-retest analysis revealed an intraclass correlation coefficient of 0.78. The COST-K had moderate correlation (r = -0.60) with the financial difficulty item of the EORTC QLQ-C30 and week correlation with the items on acute and chronic symptom burdens (nausea/vomiting = -0.18, constipation = -0.14, diarrhea = -0.14), showing good convergent and divergent validity. The median COST-K was 27 (range, 0-44; mean ± SD, 27.1 ± 7.5) and about 30% and 5% of cancer survivors experienced mild and severe financial toxicity, respectively. Younger age, lower education, lower household income was associated with higher financial toxicity. CONCLUSION: The COST-K is a valid and reliable instrument for measuring financial toxicity in disease-free breast cancer survivors. Considering its impact on the HRQOL, more studies need to be conducted to evaluate financial toxicity in cancer survivors and design interventions.

Topic(s): Economic Burden
Health Condition(s): Cancer
Year Published: 2021
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