Trigger Tools represent a robust method for identifying adverse events and can give hospitals an overall measure of unanticipated patient harm from care. Trigger tool methodology entails a retrospective chart review using “triggers” (e.g. specific medications, laboratory values) to identify patient harm. While triggers represent clues to an adverse event, a trigger cannot differentiate between events associated with the underlying diseases from those due to the medical care.  Thus a chart review is necessary to determine whether or not a true adverse event did occur.

The literature suggests that traditional methods to identify adverse events (ie: incident reporting systems, non-triggered chart reviews) only capture 10-20% of errors that actually occur.  Of these reported errors, 90-95% result in no harm to patients. This begs the question of how to identify and describe the occurrence of the harm to patients that is not currently captured.

Applying trigger tools to a chart review process gives organizations an effective way to estimate the frequency and extent of adverse events. Thereafter, strategies implemented to improve safety can be evaluated in part by finding changes in the incidence of adverse events. In essence, trigger tools offer a strategy for measuring safety over time.