Our study represents one of the largest, multicenter attempts to examine the relationship between safety culture and outcomes. We found that lower perceptions of management were independently associated with increased hospital mortality and that the magnitude of this association was comparable to a moderate increase in SAPS II score, such as from severe hypertension or advanced age. We also found that lower safety climate, expressed as perceptions of organizational commitment to safety, was independently associated with increased hospital LOS. However, our study's moderate survey response and lack of robustness to sensitivity analysis limit our ability to draw definitive conclusions.
Perceptions of management refers to approval of hospital managerial actions, and is derived from survey items such as ‘Hospital administration supports my daily efforts’ and ‘Hospital management does not knowingly compromise the safety of patients’ [14
]. Although West et al.
] surveyed human resource directors, and not the personnel, of acute care hospitals, they similarly found association between human resource practices and patient mortality. Several reasons might explain our finding. First, poor perceptions of management may represent poor management per se, or poor perceptions of in fact effective management. However, as part of effective management is communication and attention to perception, poor personnel perceptions of management likely do reflect poor management. Second, ICU personnel that disapprove of hospital management may feel less vested in their work, with attendant decrement to bedside patient care. Third, high patient mortality itself may lead to personnel burnout and stress, which may worsen perceptions of hospital management. Lastly, and most concerning, poor perceptions of management may reflect poor hospital management practices that negatively impact patient outcome.
Safety climate refers to perceptions of a strong and proactive organizational commitment to safety, and is derived from survey items such as ‘Medical errors are handled appropriately in this ICU’ and ‘I would feel safe being treated here as a patient’ [14
]. Poor attention to safety may lead to poor care, medical errors and subsequent increased LOS. A small study recently reported that implementation of a comprehensive unit-based safety program in two ICUs resulted in improved safety climate, as well as reduction in LOS and medication errors [24
]. This pilot interventional study supports the notion that safety climate and LOS are related and provides preliminary evidence that interventions targeted at improving safety can improve both culture and outcome.
Bedside caregivers have direct knowledge of how hospital policy affects patient care and can provide unvarnished insight into the safety culture of their hospital. Despite the inherent ‘chicken or egg’ caveat of observational studies, our results suggest that increased attention to ICU personnel's perceptions of their hospital's management practices and commitment to patient safety may be warranted, and that ICUs that score poorly in these areas merit evaluation. Of note, our study's lack of finding of association between the other safety culture factors and outcome does not mean that, for example, teamwork should be ignored. Our null finding may represent the relatively greater importance of perceptions of management and safety climate for outcome, or that our study design or survey instrument lacked the power or sensitivity to find smaller associations. A recent study that failed to find a significant association between Leapfrog safety survey scores and hospital mortality similarly concluded that their null result may have been due to lack of power, but that their findings should not be interpreted as indicating that safe practices are not important [25
]. Non-response bias may also have limited our ability to detect a signal. Although difficult to determine bias direction, it is possible that ICU personnel dissatisfied with their work environment had lower response rates. This would result in falsely higher safety culture scores and obscure any safety culture–outcome relationship. Our results illustrate the challenge of measuring safety culture amongst healthcare personnel, who often have poor response rates [26
]. Future work should examine the determinants of survey non-response and safety culture in healthcare, and whether interventions and management changes that improve safety culture also improve outcome.
Our study's main limitation is its moderate response rate. We used multiple strategies to minimize non-response, including endorsement from PICCM, use of a 1-page questionnaire and incentives [27
]. However, achieving high response rates among healthcare personnel is a well-known challenge in survey research, and our overall response rate of almost half is comparable to recent safety culture [28
] and provider workforce studies [30
]. We attempted to describe potential non-response bias by performing multiple post hoc
sensitivity analyses. Adding ICU-level survey response rate to our regression models had minimal impact and we found little evidence for a significant relationship between ICU-level survey response rate, and severity-adjusted mortality and hospital and ICU characteristics. However, restricting analyses to those ICUs with higher response rates yielded some counterintuitive results and perceptions of management no longer appeared significant. The lack of robustness to post hoc
sensitivity analysis for perceptions of management may be due to a true lack of association, or lower power from the smaller number of analyzed ICUs. The lower mortality of higher response ICUs, combined with their higher and more uniform perceptions of management scores, may have also made detection of a culture–outcome relationship difficult. Notably, worse safety climate was consistently associated with longer LOS, even when restricting analysis to the higher response ICUs. This suggests that safety climate may be the culture factor most robustly associated with patient outcome. A recent study similarly found that hospitals with better safety climate had lower relative incidence of patient safety related adverse events [29
Our study cohort was a self-selected group of predominantly community, non-profit, mixed medical/surgical ICUs that devote financial and staffing resources to participate in PICCM, and thus generalizability to other ICUs may be limited. We also were only able to recruit a subset of all PICCM ICUs. A previous safety culture study similarly found it necessary to contact more than 90 hospitals to obtain a 30 hospital sample and reported that safety performance was not consistently related to study participation [32
]. However, analyzing ICUs with a high degree of uniformity and commitment to self-appraisal would likely bias against finding a signal between safety culture and patient outcomes. Although determining direction of bias is difficult, a broader and larger sample would have provided greater power to answer study objectives. We analyzed patient outcome data from a wider time period that encompassed our survey administration time period as organizational culture changes slowly and to provide a larger analysis sample. Significant culture variation during this time period could have potentially distorted study findings. Lastly, although most survey respondents were nurses, nurses comprise the bulk of an ICU's personnel, are physically in the ICU most, and thus nurses may contribute the most to an ICU's overall culture.