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

• Published in: Cancer research and treatment Vol. 54; no. 3; pp. 834 - 841
• Main Authors: Shim, Sungkeun, Kang, Danbee, Kim, Nayeon, Han, Gayeon, Lim, Jihyun, Kim, Hyunsoo, Park, Jeonghyun, Lee, Mankyung, Lee, Jeong Eon, Kim, Seok Won, Yu, Jonghan, Chae, Byung Joo, Ryu, Jai Min, Nam, Seok Jin, Lee, Se Kyung, Cho, Juhee
• Format: Journal Article
• Language: English
• Published: Korea (South) Korean Cancer Association 01.07.2022; 대한암학회
• Subjects: Original; 의학일반; Cancer survivors; Financial toxicity; Breast neoplasms; Quality of life; Validation study
• ISSN: 1598-2998; 2005-9256; 2005-9256
• DOI: 10.4143/crt.2021.784

Purpose Little is known about the impact of financial toxicity in disease-free breast cancer survivors. We aim to validate the COmprehensive Score for financial Toxicity 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 Functional Assessment of Chronic Illness Therapy multilingual translation (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 European Organization for Research and Treatment of Cancer Quality of Life Core 30 (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 to 44; mean±standard deivation [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 health-related quality of life, more studies need to be conducted to evaluate financial toxicity in cancer survivors and design interventions.