Intensive care unit safety culture and outcomes: a US multicenter study

Abstract

Objective: Safety culture may influence patient outcomes, but evidence is limited. We sought to determine if intensive care unit (ICU) safety culture is independently associated with outcomes.

Design: Cohort study combining safety culture survey data with the Project IMPACT Critical Care Medicine (PICCM) clinical database.

Setting: Thirty ICUs participating in the PICCM database.

Participants: A total of 65 978 patients admitted January 2001-March 2005.

Interventions: None.

Main outcome measures: Hospital mortality and length of stay (LOS).

Methods: From December 2003 to April 2004, we surveyed study ICUs using the Safety Attitudes Questionnaire-ICU version, a validated instrument that assesses safety culture across six factors. We calculated factor mean and percent-positive scores (% respondents with mean score > or =75 on a 0-100 scale) for each ICU, and generated case-mix adjusted, patient-level, ICU-clustered regression analyses to determine the independent association of safety culture and outcome.

Results: We achieved a 47.9% response (2103 of 4373 ICU personnel). Culture scores were mostly low to moderate and varied across ICUs (range: 13-88, percent-positive scores). After adjustment for patient, hospital and ICU characteristics, for every 10% decrease in ICU perceptions of management percent-positive score, the odds ratio for hospital mortality was 1.24 (95% CI: 1.07-1.44; P = 0.005). For every 10% decrease in ICU safety climate percent-positive score, LOS increased 15% (95% CI: 1-30%; P = 0.03). Sensitivity analyses for non-response bias consistently associated safety climate with outcome, but also yielded some counterintuitive results.

Conclusion: In a multicenter study conducted in the USA, perceptions of management and safety climate were moderately associated with outcomes. Future work should further develop methods of assessing safety culture and association with outcomes.

Figure 1

Percentage of positive safety culture scores across ICUs (n = 30).

Figure 2

Relationship between perceptions of management and hospital mortality, and between safety climate and hospital LOS. Top panel: Perceptions of management are expressed as the percentage of ICU personnel with a positive perception of management (% positive). The adjusted odds of hospital mortality are presented relative to the ICU with the highest % positive score for perceptions of management. Dashed lines represent the 95% CIs for the estimated odds ratios. The markers indicate the specific % positive scores for perceptions of management for the 30 study ICUs. Bottom panel: Safety climate is expressed as the percentage of ICU personnel with a positive safety climate score (% positive). The adjusted multiplicative change in LOS is presented relative to the ICU with the highest % positive score for safety climate. Dashed lines represent the 95% CIs for the estimated percent change. The markers indicate the specific % positive scores for safety climate for the 30 study ICUs.