Initially 36 triggers were identified. Applying these to 109.6 patient-years of
records for 170 patients, we identified harm in the records of 46 (27.1%) patients.
There were 7 occurrences of harm per 100 consultations (harm rate per
consultation=0.07 (95% confidence interval [CI] 0.05–0.09) and 41 per 100
consulting patient years (95%CI 29–55). All harms related to medication use. The
initial triggers were sensitive (0.98) but non-specific (0.08): removing triggers with
low specificity left only 8. The OR for harm occurring using the initial triggers was
4.0 (95% 0.5-30) and using the refined trigger set OR=6.3 (95%CI 2.7–14.8).