A systematic review of financial toxicity measurement instruments for cancer patients based on the COSMIN guideline

Abstract Objective Financial toxicity, characterized by the financial burden and psychological distress associated with cancer treatment, has become a critical issue impacting patient outcomes and quality of life. This study aimed to conduct an updated and comprehensive systematic review to evaluate the methodological quality and measurement properties of financial toxicity measurement instruments for cancer patients, thereby guiding the selection of high-quality tools for future empirical research. Methods Literature on financial toxicity measurement instruments for cancer patients was retrieved from CNKI, Wanfang, VIP, SinoMed, PubMed, Web of Science, CINAHL, Scopus, and Embase databases, with a search range from the inception up to April 16, 2025. Two researchers independently screened the literature and extracted data. The included studies were assessed using the Consensus-Based Standards for the Selection of Health Measurement Instruments (COSMIN), and recommendations were formulated based on the quality of evidence and measurement properties. Results A total of eighteen studies were included, involving eight financial toxicity measurement instruments for cancer patients. None of the studies reported measurement error. The Comprehensive Score for Financial Toxicity (COST), Financial Index of Toxicity (FIT), and Subjective Financial Distress Questionnaire (SFDQ) were provisionally recommended for use (Category B), while the other five instruments were not recommended due to insufficient evidence (Category C). Conclusion The COST is provisionally recommended for measuring financial toxicity in cancer patients. The methodological quality and measurement properties of existing financial toxicity instruments still require further improvement. Future research should adhere strictly to the COSMIN guideline to validate existing tools or develop new, high-quality instruments with comprehensive evaluations of their measurement properties.