Validity and Reliability of the Portuguese Version of the Nurses’ Professionalism Inventory

Background/Objectives: Professionalism reflects an individual’s connection, identity, and dedication to their profession. In nursing, it is associated with quality of care and professional respect, making its assessment essential for workforce development and management. However, valid and reliable instruments are needed to measure this construct across cultural contexts. Therefore, this study aims to evaluate the validity and reliability of the Portuguese version of the Nurses’ Professionalism Inventory (NPI). Methods: This methodological study used cross-sectional data collected from November 2024 to January 2025 in northern Portugal. Data were gathered from a convenience sample of 684 nurses who completed a sociodemographic questionnaire, the Portuguese NPI, the Conditions of Work Effectiveness Questionnaire II (CWEQ-II), and the Team Psychological Safety (TPS) scale. Confirmatory Factor Analysis (CFA) was conducted. Factor loadings and Average Variance Extracted (AVE) were used to assess validity. Internal consistency was evaluated using Composite Reliability, McDonald’s omega, and Cronbach’s alpha. Convergent validity was examined using Spearman correlations among NPI subscales, CWEQ-II dimensions, and TPS. Results: The Portuguese version of NPI preserved the original five-factor structure. The model showed acceptable fit indices (TLI = 0.90; CFI: 0.91; RMSEA = 0.10; SRMR = 0.08). All items had factor loadings above 0.50, except item 18 (0.42), which did not load significantly on any other factor; therefore, it was removed. This improved the AVE of the Professional Attitude subscale. The overall internal consistency was satisfactory, with all reliability coefficients ranging between 0.73 and 0.99. The correlations among the NPI subscales, CWEQ-II dimensions, and TPS were positive and statistically significant. Conclusions: This study demonstrates adequate measurement properties of the Portuguese version of NPI, supporting its use as a valid and reliable instrument.