IHI Outpatient Adverse Event Trigger Tool

​Institute for Healthcare Improvement (in association with Kaiser Permanente and Baylor Health Care System)
Cambridge, Massachusetts, USA

The use of “triggers,” or clues, to identify adverse events is an effective method for measuring the overall level of harm from medical care in an organization.

The outpatient continuum has proved especially difficult because a different technique for analysis of adverse events is required. The inpatient Trigger Tool methodologies are limited to a single inpatient experience. A single outpatient experience is time and exposure limited, which makes the practicality of adverse event identification very difficult. By necessity, a process of banding together multiple episodes of care across the continuum must be utilized.

A methodology was developed using triggers derived from malpractice claims data to identify outpatient-related adverse events. The Outpatient Trigger Tool uses eleven triggers to provide “clues” to the possibility of adverse events in a patient record.

For more general information on Trigger Tools and how to select the appropriate one, see the Introduction to Trigger Tools page.


Knowledge and expertise gained from using the Trigger Tool in the hospital setting, both as a global and specialty area tool, has generated interest in a tool for determining events in the outpatient setting. The identification of events in the outpatient setting is made more difficult by the short episodes of care occurring over time in multiple different settings.

In 2001 the Institute for Healthcare Improvement (IHI) started the initial work on the Outpatient Adverse Event Trigger Tool. In 2005 and 2006 the outpatient methodology was tested at Kaiser Permanente and Baylor Health System with input from IHI faculty. The Outpatient Trigger Tool has been tested on hundreds of patient charts representing hundreds of patient years and this toolkit represents the latest version of the tool.



This tool contains:

  • Introduction
  • Definition of Adverse Events
  • Explanation of Trigger Tool Methodology
  • Triggers and Definitions
  • Individual Record Review Sheet
  • Summary Data Collection Form
  • Classification of Event Severity
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