ABSTRACT
PURPOSE: Multiple myeloma (MM) is a rare but treatable hematological cancer, which makes the health-related quality of life (HRQoL) an important patient-report outcome measure in clinical studies. The Quality of Life Questionnaire Multiple Myeloma Module (QLQ-MY20) was developed by the European Organization for Research and Treatment of Cancer (EORTC) to measure HRQoL in people with MM. However, the Brazilian Portuguese version of QLQ-MY20 has not yet been validated for Brazil. This study aimed to evaluate the validity and reliability of the instrument for application in Brazilian patients with MM. METHODS: This is a cross-sectional methodological study with patients seen in health services in Belo Horizonte, Brazil. The variables were collected through face-to-face interviews with the QLQ-MY20 instrument and complemented with data from medical records. Content validity analyses (content validity coefficient [CVC]; correctness ratio), convergent and divergent validity (Spearman's correlation coefficient [CC]), internal consistency, and temporal reproducibility (test-retest; intraclass correlation coefficient [ICC]) were performed. RESULTS: 225 patients were included and 71.1% were older than 60. The analysis of the judging committee showed adequate content validity. We observed mainly a good internal consistency of the items and good discrimination power in the convergent and divergent validity. High ICC values were observed through the test-retest, and there was no difference in the scores between the two moments, which shows good temporal stability of the instrument. CONCLUSION: The study allowed us to conclude that the Brazilian version of the QLQ-MY20 module is valid and reliable, and thus suitable for application in Brazilians living with MM.