Development and Validation of the Oxford Skin Cancer Treatment Scale, a Patient-Reported Outcome Measure for Health-Related Quality of Life and Treatment Satisfaction After Skin Cancer Treatment

Abstract

BACKGROUND Patient-reported outcome measures (PROMs) are necessary to assess the value of skin cancer treatment and to better compare therapeutic options. OBJECTIVE To develop and validate the Oxford Skin Cancer Treatment (OxSCanTr) scale, evaluating health-related quality of life and satisfaction after skin cancer treatment. MATERIALS AND METHODS After qualitative patient interviews, international expert consultation, and item reduction, 2 separate patient samples were used to assess the factor structure of the scale. Exploratory factor analysis with categorical variables and a polychoric correlation matrix followed by promax oblique rotation was performed to establish a factor structure on Group A. Confirmatory factor analysis with a Satorra–Bentler scaled test statistic evaluating the root mean squared error of approximation (RMSEA), standardized root mean squared residual (SRMR), and comparative fit index (CFI) was conducted on Group B. Reliability as internal consistency was assessed using McDonald omega. Convergent and discriminant validity were assessed using the Pearson correlation coefficient. RESULTS A total of 480 subjects returned completed surveys (completion rate 96%). A 12-item scale was developed encompassing 4 domains: aesthetic satisfaction, treatment choice satisfaction, treatment experience, and future concerns regarding recurrence/spread. Confirmatory factor analysis showed excellent goodness-of-fit characteristics, with RMSEA = 0.048, SRMR = 0.051, and CFI = 0.962 using the 4-factor model. Reliability was very good (McDonald omega 0.81–0.82), as was convergent validity with the FACE-Q skin cancer module appraisal of scars subscale (r = 0.55). Discriminant validity with a single question regarding being conservative was similarly excellent (r = −0.02). CONCLUSION The OxSCanTr scale is a parsimonious, feasible, and valid PROM for the holistic assessment of the experience of patients who have undergone skin cancer treatment.