RESUMEN
BACKGROUND: Valid and reliable instruments are needed to measure prostate cancer-related lifestyle changes, plan evidence-based interventions to modify lifestyle, and improve treatment outcomes. Due to the lack of appropriate instruments, this study was conducted to translate the Effects of Prostate Cancer upon Lifestyle Questionnaire (EPCLQ) into Persian and examine its psychometric properties in a sample of Iranian older adults with prostate cancer. METHODS: This methodological study was carried out between 2021 and 2022. Initially, the EPCLQ, comprising 36 items, was translated into Persian through a meticulous translation and back-translation procedure. Subsequent steps involved the assessment of face validity, qualitative content validity, content validity index, content validity ratio, construct validity via confirmatory factor analysis, and reliability testing of the Persian version of the EPCLQ. RESULTS: The psychometric evaluation led to the exclusion of 4 items from the EPCLQ. The refined model demonstrated satisfactory fit indices (PCFI = 0.732, PNFI = 0.696, CMIN/DF = 2.29, RMSEA = 0.072, IFI = 0.920, CFI = 0.919, and GFI = 0.971), indicating an appropriate fit of the final model. The internal consistency, as measured by Cronbach's alpha, was 0.67, and the intraclass correlation coefficient for the questionnaire was 0.938, reflecting high reliability. CONCLUSIONS: The Persian version of the EPCLQ, now consisting of 32 items, has been validated and is reliable for assessing the impact of prostate cancer on lifestyle among older adults. Its simplicity and the clarity of the items make it suitable for use in clinical settings or during home visits for follow-up assessments.