Advancing measurement of patient safety culture.

Objective: To examine the psychometric and unit of analysis/strength of culture issues in patient safety culture (PSC) measurement.

Data Source: Two cross-sectional surveys of health care staff in 10 Canadian health care organizations totaling 11,586 respondents.

Study Design: A cross-validation study of a measure of PSC using survey data gathered using the Modified Stanford PSC survey (MSI-2005 and MSI-2006); a within-group agreement analysis of MSI-2006 data. Extraction Methods. Exploratory factor analyses (EFA) of the MSI-05 survey data and confirmatory factor analysis (CFA) of the MSI-06 survey data; Rwg coefficients of homogeneity were calculated for 37 units and six organizations in the MSI-06 data set to examine within-group agreement.

Principal Findings: The CFA did not yield acceptable levels of fit. EFA and reliability analysis of MSI-06 data suggest two reliable dimensions of PSC: Organization leadership for safety (alpha=0.88) and Unit leadership for safety (alpha=0.81). Within-group agreement analysis shows stronger within-unit agreement than within-organization agreement on assessed PSC dimensions.

Conclusions: The field of PSC measurement has not been able to meet strict requirements for sound measurement using conventional approaches of CFA. Additional work is needed to identify and soundly measure key dimensions of PSC. The field would also benefit from further attention to strength of culture/unit of analysis issues.