The application of the Global Trigger Tool: a systematic review.

Purpose: This study describes the use of, and modifications and additions made to, the Global Trigger Tool (GTT) since its first release in 2003, and summarizes its findings with respect to counting and characterizing adverse events (AEs).

Data sources: Peer-reviewed literature up to 31st December 2014.

Study selection: A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement.

Data extraction: Two authors extracted and compiled the demographics, methodologies and results of the selected studies.

Results of data synthesis: Of the 48 studies meeting the eligibility criteria, 44 collected data from inpatient medical records and four from general practice records. Studies were undertaken in 16 countries. Over half did not follow the standard GTT protocol regarding the number of reviewers used. 'Acts of omission' were included in one quarter of studies. Incident reporting detected between 2% and 8% of AEs that were detected with the GTT. Rates of AEs varied in general inpatient studies between 7% and 40%. Infections, problems with surgical procedures and medication were the most common incident types.

Conclusion: The GTT is a flexible tool used in a range of settings with varied applications. Substantial differences in AE rates were evident across studies, most likely associated with methodological differences and disparate reviewer interpretations. AE rates should not be compared between institutions or studies. Recommendations include adding 'omission' AEs, using preventability scores for priority setting, and re-framing the GTT's purpose to understand and characterize AEs rather than just counting them.