Traditional efforts to detect adverse events* (AEs) have focused on voluntary reporting and tracking of errors. However, public health researchers have established that only 10 to 20 percent of errors are ever reported and, of those, 90 to 95 percent cause no harm to patients. Hospitals need a more effective way to identify events that do cause harm to patients, in order to select and test changes to reduce harm.

Tracking AEs per 1,000 days over time is a useful way to tell if changes made at an organization are improving the safety of the system.

*An adverse drug event is defined as harm to the patient from medications, whether or not the result of an error.

Decrease the number of AEs to 1 per 1,000 days.

Every month, select a random sample of at least 20 closed patient records, each with a minimum stay of 24 hours.  Review the records, looking for “triggers” — certain medications, laboratory values, or events — that often provide clues that an AE has occurred. Investigate each trigger further to determine if an AE did in fact occur. Count the total number of days that each patient was in the hospital.

The Global Trigger Tool for Measuring AEs provides instructions for conducting a retrospective review of patient records using triggers to identify possible AEs. This tool includes a list of known AE triggers and instructions for measuring the number and degree of harmful events.