11 Cross-Cultural Adaptation and External Validation of the Locally Recurrent Rectal Cancer – Quality of Life (LRRC-QoL) Measure

Abstract Background Establishing an international measure of health-related quality of life (HrQoL) for patients with LRRC is central to understanding its impact from a patient perspective. The aim of this study was to cross-culturally adapt and externally validate the LRRC-QoL as an international measure of HrQoL in LRRC. Methods A multi-phase mixed methodological study was conducted. Cross-cultural adaptation was undertaken through Translatability Assessment (TA), forward-backward translation, and pre-testing interviews to establish content validity and conceptual equivalence. External validation included assessing scale structure through confirmatory factor analysis (CFA), reliability using Cronbach’s Alpha and Intraclass Correlation Coefficient (ICC). Convergent validity was assessed against EORTC QLQ-CR29 and FACT-C scales using Pearson’s Correlation Coefficient (r). Known groups comparison through independent t-tests and ANOVA. Responsiveness through effect sizes (ES) and standardised response means (SRM). Results Sixty-seven patients and 6 clinicians were recruited to pre-testing interviews to cross-culturally adapt the LRRC-QoL for use in 10 languages. Overall, 321 patients were included in the validation of the LRRC-QoL from 16 countries. The scale structure demonstrated excellent goodness of fit. Most scales demonstrated good reliability (Cronbach’s Alpha and ICC >0.7). Convergent validity confirmed hypothesised correlations. Known groups validity was demonstrated for gender, pattern of recurrence, pre-operative treatment, treatment intent, and metastases. The LRRC-QoL demonstrated excellent responsiveness; patients undergoing surgery reported worse HrQoL at 3- (p=0.00, ES 0.57, SRM 0.50) and 6-months (p=0.001, ES 0.37, SRM 1.11). Conclusion The LRRC-QoL has demonstrated excellent psychometric properties in this international validation analysis and is now validated for use in 16 countries.