Hospital-Wide Measures Do Not Tell the Whole Story

Building on earlier research showing broad variation in patient safety culture within individual hospitals, Dutch investigators evaluated the rate of preventable adverse events, both between hospitals and between hospital departments. Twenty percent of all Dutch hospitals were included in the study. 7,113 patient admissions to 300 hospital departments in 21 hospitals were reviewed.A trained team of 66 nurses and 55 physicians participated in a structured record review process, and two physicians reviewed each possible adverse event to confirm it, evaluate preventability and assign a responsible department.

After correcting for risk factors and hospital type, variance between hospitals was not significant while variance at the department level was. The corrected event rates at the department level varied from 1.0 to 9.6 percent, and the interclass correlation (a measure of event clustering) was almost three times higher when measured at the department level than at the hospital level.

The authors recommend that: “Hospitals with an overall low rate of adverse events may have departments with the high rates of adverse events. Measurement at the department level is also more appropriate to formulate interventions and implementation strategies tailored to the problems of specific hospital departments. Hospital managers should identify high-risk departments and safety programs should focus on patient groups or clinical areas with a higher risk of preventable adverse events, such as elderly patients and patients that undergo surgical procedures.”


Zegers M, Bruijne MC De, Spreeuwenberg P, et al. Variation in the rates of adverse events between hospitals and hospital departments. International journal for quality in health care: journal of the International Society for Quality in Health Care. 2011;23(2):126–33.