Survey and Patient-Reported Outcome Measure Instruments for Assessing Out-of-Pocket Costs and Financial Toxicity in Cancer Care: A Systematic Review.

OBJECTIVES: Out-of-pocket (OOP) costs and financial toxicity remain significant barriers to equitable cancer care globally. This review systematically identifies and compares survey-based approaches used to measure patient- and household-level OOP expenditures and financial burden across diverse cancer settings. METHODS: A systematic search (2021-2025) of PubMed, Embase, and EBSCO databases identified studies that used survey methodologies, including patient-reported outcome measure instruments to estimate OOP spending and financial toxicity among cancer patients. Two reviewers independently screened studies and extracted data on key methodological characteristics including instrument type, cost domains, recall periods, validation practices, and reporting conventions to compare measurement approaches across studies. RESULTS: Based on the eligibility criteria, 45 studies were included. Survey tools showed substantial heterogeneity in structure, terminology, and measurement practices. Studies differed widely in the cost domains captured (direct medical, direct nonmedical, and indirect costs) and used recall periods ranging from a few days to 156 months. Reporting of currency, cost year, and conversion methods was inconsistent. Most relied on bespoke, nonvalidated questionnaires to measure objective financial burden, whereas validated patient-reported outcome measures, such as the Comprehensive Score for Financial Toxicity (COST) measures, were used inconsistently for subjective financial distress. This methodological variation substantially limited comparability across studies and hindered synthesis of patient-level financial burden. CONCLUSIONS: Survey-based methods for measuring OOP costs and financial burden in cancer care remain highly variable. Establishing minimum methodological and reporting standards for core cost domains, recall periods, and financial burden indicators may improve comparability of evidence while allowing context-specific adaptation across health systems.