Validation of a Single Item Measure for Financial Toxicity Screening in Patients With Breast Cancer

Financial toxicity (FT) has been linked to higher symptom burden and poorer clinical outcomes for patients with cancer. Despite the availability of validated tools to measure FT, a simple screen remains an unmet need. We evaluated item 12 ("My illness has been a financial hardship to my family and me") of the COmprehensive Score for Financial Toxicity (COST) measure as a single-item FT screening measure.

In this secondary analysis, 711 patients with cancer (690 with breast cancer) were recruited via a web-based survey from a philanthropic organization. COST items 1-11 were scored according to Functional Assessment of Chronic Illness Therapy scoring guidelines, with lower scores indicating worse FT. Analyses focused on establishing a correlation, examining item properties, and sensitivity/specificity of item 12 relative to the total COST score.

Item 12 had a correlation of r = 0.53 with the COST-11 score, and an increase of one point on item 12 is associated with a decrease of approximately three total points on the full scale (b, 3.35; P < .001; adjusted R², 0.28). Item analysis with the graded-response item in response theory modeling showed very good discrimination (a, 2.096) for item 12, indicating that it can reliably distinguish between low and high FT in patients. Sensitivity ranged between 75.6% and 95.7% on all item 12 thresholds to screen positive for FT using two COST cutoffs as criteria. Maximizing both sensitivity and specificity was to be found for higher item 12 scores.

To our knowledge, this is the first validation of a single-item screening measure for FT. Overall, these results illustrate that item 12 from the COST measure is a good candidate for a single-item screener. Clinicians can choose among item 12 screening thresholds depending on their tolerance for low specificity.