The development and psychometric validation of culture of patient safety scale under Rasch objective measurement theory

Background: Assessing the culture of patient safety in healthcare settings is pivotal for continuously reinforcing effective, safe and quality patient care. However, most of the rating scales lack evidence of objective validation of the measuring instruments.
Aim: To determine the psychometric properties of culture of patient safety scale under the Rasch objective measurement theory.
Method: The validation of the culture of safety scale was underpinned by the four stages of rating scale development in Rasch objective measurement theory. The first stage involved literature review to shortlist items considered theoretically relevant to culture of patient safety in hospital settings. In the second stage, a panel of academic and practitioners individually reviewed the selected items to give external face validity based on professional experiences. In the third stage, 967 participants from public maternity settings in Nigeria voluntarily accessed the nine items forming the culture of patient safety scale online over eight weeks period. Ethical approval was given by the nurses’ association and University of Huddersfield. Subsequently, all the data were exported to SPSS and Winsteps version 5.0.0.0 for evaluation of the psychometric assumptions. Essential psychometric properties evaluated are dimensionality, category functioning, item difficulty/agreeability, local independence, reliability and item validity. In the fourth stage, problematic items were identified and moderated based on the outcome of the measurement assumptions. Consequently, final decisions made included retention, modification or expulsion of items making no meaningful contribution to the variable measurement.
Conclusion and implication:
The culture of safety scale has excellent psychometric properties and therefore recommended for use among practitioners and researchers.