Abstract
BACKGROUND: Blood transfusion is a high-risk procedure that requires technical accuracy, clinical judgment and adherence to safety protocols. Despite nurses' central role in transfusion care, no validated instrument exists to comprehensively assess global competence in this context. The absence of standardized measures limits educational planning, performance evaluation and the development of policies aimed at strengthening transfusion safety. This study aimed to develop and psychometrically evaluate the Hemotransfusion Nursing Global Competence Scale, designed to measure nurses' overall competence in the transfusion process. METHODS: A psychometric methodological study based on Classical Test Theory was conducted in three phases. Phase 1 included construct definition and development of 41 items across cognitive, clinical, behavioral and psychomotor domains. Phase 2 involved content validation by 15 national experts using the Content Validity Ratio. Phase 3 evaluated the internal structure and psychometric properties with 529 Brazilian nurses through exploratory factor analysis, confirmatory factor analysis and internal consistency indicators. RESULTS: All items were judged essential by experts, demonstrating strong content validity. Exploratory factor analysis supported a robust unidimensional structure with high factor loadings, while confirmatory factor analysis confirmed excellent model fit (CFI > 0.99; TLI > 0.99; RMSEA = 0.039). Reliability was exceptional (Cronbach's α = 0.992; McDonald's ω = 0.999). Item-total correlations and "if deleted" indices supported retention of all 41 items, indicating a stable and precise measure of global transfusion competence. CONCLUSIONS: The scale is a valid, reliable and theoretically grounded instrument for assessing nurses' overall competence in blood transfusion. Its unidimensional structure reflects the integrated nature of transfusion skills and supports comprehensive evaluation in clinical and educational settings.