INTRODUCTION Safe practice and safety culture are important issues in outpatient diagnostic imaging services. As questionnaires assessing safety culture through the measurement of safety climate in this setting are not yet available, the present study aimed to develop and validate such an instrument.
MATERIALS AND METHODS After adaptation of an existing questionnaire and qualitative pretesting, the instrument was tested by collaborators from three outpatient imaging services in Switzerland. Results were first assessed using descriptive statistics. Scores of individual services were compared using a Wilcoxon test assessing differences between rank distributions. The final instrument was tested for validity using inter-rater agreement measures, such as reliability within groups (r), and an intraclass correlation coefficient measure (ICC(1)). These measures allowed the assessment of validity of aggregation into a total score (r) and validated the instrument for its capacity to distinguish various safety climates of different groups by comparing inter-rater agreement in the overall sample to inter-rater agreement of individual services (r) and by measuring group effects (ICC(1)). Furthermore, the final instrument was tested for internal consistency and reliability using Cronbach's Alpha.
RESULTS Safety climate scores vary significantly between services. Inter-rater agreement measures show that item aggregation is justified and that the instrument distinguishes various patterns of safety climate. The final instrument proves to be valid, consistent and reliable.
CONCLUSIONS The final instrument presents a valid, consistent and reliable option to measure safety climate in outpatient diagnostic imaging services. Results can be used as a basis for quality improvement.
KEY POINTS An adapted questionnaire that assesses safety climate in outpatient diagnostic imaging services was developed and tested in Switzerland. • Psychometric evaluation showed the questionnaire to be a valid, consistent and reliable instrument. • Results are of interest for imaging services as well as for stakeholders interested more globally in monitoring and quality improvement.