Does increasing the size of bi-weekly samples of records influence results when using the Global Trigger Tool? An observational study of retrospective record reviews of two different sample sizes.
OBJECTIVE
To investigate the impact of increasing sample of records reviewed bi-weekly with the Global Trigger Tool method to identify adverse events in hospitalised patients.


METHODS
Retrospective observational study.


METHODS
A Norwegian 524-bed general hospital trust.


METHODS
1920 medical records selected from 1 January to 31 December 2010.


METHODS
Rate, type and severity of adverse events identified in two different samples sizes of records selected as 10 and 70 records, bi-weekly.


RESULTS
In the large sample, 1.45 (95% CI 1.07 to 1.97) times more adverse events per 1000 patient days (39.3 adverse events/1000 patient days) were identified than in the small sample (27.2 adverse events/1000 patient days). Hospital-acquired infections were the most common category of adverse events in both the samples, and the distributions of the other categories of adverse events did not differ significantly between the samples. The distribution of severity level of adverse events did not differ between the samples.


CONCLUSIONS
The findings suggest that while the distribution of categories and severity are not dependent on the sample size, the rate of adverse events is. Further studies are needed to conclude if the optimal sample size may need to be adjusted based on the hospital size in order to detect a more accurate rate of adverse events.
Regional Patient Safety Resource Center, Nordland Hospital Trust, Bodø, Norway.
Kjersti
K
Mevik
Fran Griffin & Associates, LLC, Neptune, New Jersey, USA.
Frances A
FA
Griffin
Nordland Hospital Trust, Bodø, Norway.
Tonje E
TE
Hansen
Center for Health Service Research, Akershus University Hospital, Lørenskog, Norway.
Ellen T
ET
Deilkås
CMO, Nordland Hospital Trust, Bodø, Norway.
Barthold
B
Vonen
D064420:Drug-Related Side Effects and Adverse Reactions / Q000517:prevention & control*; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006784:Hospitals, Teaching / Q000458:organization & administration*; D006801:Humans; D008297:Male; D019300:Medical Errors / Q000706:statistics & numerical data*; D008499:Medical Records; D009664:Norway / Q000453:epidemiology; D061214:Patient Safety / Q000706:statistics & numerical data; D058996:Quality Improvement / Q000458:organization & administration*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012307:Risk Factors; D018401:Sample Size
Global Trigger Tool; QUALITATIVE RESEARCH; Sample size