It is now beyond dispute that adverse events due to medical error are a leading cause of premature mortality. Some research suggests that 0.6% of admissions result in death due to adverse events, and other serious adverse events may be even more common than this. Retrospective record review using trigger tools is a widely used method for a systematic review of adverse events in patient records. A study recently published in the BMJ investigated the contribution of severe adverse events to death amongst hospitalised patients using the Global Trigger Tool (GTT) method. 377 patients who died in the three hospitals during 2013 were included. The study found that  adverse events contributed to inpatient death in 0.3% of hospital admissions, Patients who died in hospital had twice the rate of adverse events per 1000 patient days compared to the general patient cohort: 76.7 vs 36.5 (p<0.001, RR 2.10, 95% CI 1.79 to 2.47). Patients dying in hospital experience seven times the rate of severe adverse events: 38.4% vs 5.2% (p<0.001, RR 2.10, 95% CI 1.79 to 2.47). For 86 out of 377 inpatient deaths, the adverse event is so severe that it contributed to the patient’s death. Medication-related harm (p<0.001, RR 5.21, 95% CI 3.04 to 8.94) and pressure ulcers (p=0.04, RR 2.23, 95% CI 1.03 to 4.85) were significantly more frequent for inpatient deaths than in the general sample of hospital patients. Read the full study here