OBJECTIVES: The screening of cancer patients at risk of developing financial toxicity is essential for better clinical outcomes and to alleviate the financial burden on cancer survivors. The aim of this study was to develop an instrument for the assessment of financial toxicity among radiation oncology patients.

METHODS: The items for scale development were generated through literature review, expert opinion and patient interviews. The underlying factor structure of the preliminary scale was evaluated by Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA). Factors were extracted based on Kaiser Criterion (eigenvalues˃1) and the items with factor loadings ˃0.5 were retained. The reliability of the final scale was assessed using Cronbach’s alpha coefficient.

RESULTS: A pool of 47 items was generated of which 17 items were selected for scale development. The preliminary 17-item instrument was administered to 142 Head & Neck cancer patients. Of these 85% were male, 65% were diagnosed with oral cavity cancers and 95% belonged to rural areas. EFA was performed on 17 item preliminary scale using principal component analysis. Three items with factor loadings ˂0.5 were removed and the remaining 14 items loaded onto three factors explaining 62.0% of the total variance in EFA. The 14 items with factor loadings of ˃0.5 (range 0.60-0.86) were retained. The results of CFA showed that Chi-square goodness of fit test [χ² (71) = 91.42, p ˃0.001] was not significant and the χ ²/df = 1.28 suggesting that the three factor CFA model adequately fits the data. The values of other model fit indices, RMSEA (0.045), SRMR (0.014), GFI (0.92), CFI (0.98), and TLI (0.97) also support a good model fit. The Cronbach’s α of the final 14-item scale was 0.87 demonstrating excellent reliability.

CONCLUSIONS: The SFDQ captures and integrates all the relevant domains of financial toxicity and showed excellent validity and reliability in factor-analysis.