Table 2

Description of the Global Trigger Tool and Harvard Medical Practice Study

InstrumentDescriptionSafety outcomesConducted byScale
Global Trigger Tool34Two-stage retrospective record review
Stage 1: Screening records for the presence of triggers and determining the adverse event that caused harm to patientsTriggers (mostly narrow)Stage 1: Trained nurses or hospital pharmacists (primary reviewers, mostly two reviewers per records)
Maximum 20 min per record
Dichotomous: yes/no trigger
Stage 2: Confirming or dismissing the occurrence and category of the adverse eventAdverse eventsStage 2: Trained physicians (second reviewers, mostly one reviewer)Dichotomous: yes/no AE
Definition of AE: Any unintended physical injury resulting from or contributed to by medical care that requires additional monitoring, treatment or hospitalisation or that results in death
Medical record review based on HMPS3Two-stage or three-stage retrospective record review
Stage 1: Screening records using criteria(Broad) Screening criteria (triggers)Stage 1: Trained nurses*
No time limit
Dichotomous: yes/no trigger
Stage 2: Detailed review to confirm the presence of adverse events and their preventability(Preventable) Adverse eventsStage 2: Trained physicians (one or two reviewers per record)AE determination is based on three criteria:
  1. Unintended injury to the patient (dichotomous: yes/no)

  2. Resulted in prolongation of hospital stay, temporary or permanent disability or death (dichotomous: yes/no)

  3. Caused by healthcare management (six-point scale)

Preventability: six-point scale
When criteria 1 and 2 are met and the score on criteria 3 is ≥4, then there has been an AE and an AE is preventable when the score on the preventability scale is ≥4
Stage 3: Discussion or independently supervising review (consensus stage)†Stage 3: Supervising physician
  • *With the exception of the study of Brennan et al,32 in which medical records were reviewed by medical-record-room administrators.

  • †In some studies, a third stage was used.3 ,32 ,39–42

  • AEs, adverse events; HMPS, Harvard Medical Practice Study.