A comparison of iatrogenic injury studies in Australia and the USA. I: Context, methods, casemix, population, patient and hospital characteristics.
OBJECTIVE
To better understand the differences between two iatrogenic injury studies of hospitalized patients in 1992 which used ostensibly similar methods and similar sample sizes, but had quite different findings. The Quality in Australian Health Care Study (QAHCS) reported that 16.6% of admissions were associated with adverse events (AE), whereas the Utah, Colorado Study (UTCOS) reported a rate of 2.9%.


METHODS
Hospitalized patients in Australia and the USA.


METHODS
Investigators from both studies compared methods and characteristics and identified differences. QAHCS data were then analysed using UTCOS methods.


METHODS
Differences between the studies and the comparative AE rates when these had been accounted for.


RESULTS
Both studies used a two-stage chart review process (screening nurse review followed by confirmatory physician review) to detect AEs; five important methodological differences were found: (i) QAHCS nurse reviewers referred records that documented any link to a previous admission, whereas UTCOS imposed age-related time constraints; (ii) QAHCS used a lower confidence threshold for defining medical causation; (iii) QAHCS used two physician reviewers, whereas UTCOS used one; (iv) QAHCS counted all AEs associated with an index admission whereas UTCOS counted only those determining the annual incidence; and (v) QAHCS included some types of events not included in UTCOS. When the QAHCS data were analysed using UTCOS methods, the comparative rates became 10.6% and 3.2%, respectively.


CONCLUSIONS
Five methodological differences accounted for some of the discrepancy between the two studies. Two explanations for the remaining three-fold disparity are that quality of care was worse in Australia and that medical record content and/or reviewer behaviour was different.
Thomas
E J
EJ
Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA. eric.thomas@uth.tmc.edu
Studdert
D M
DM
Runciman
W B
WB
Webb
R K
RK
Sexton
E J
EJ
Wilson
R M
RM
Gibberd
R W
RW
Harrison
B T
BT
Brennan
T A
TA
D000293:Adolescent; D000328:Adult; D000368:Aged; D001315:Australia / Q000453:epidemiology; D019985:Benchmarking / Q000379:methods* / Q000706:statistics & numerical data; D002648:Child; D002675:Child, Preschool; D003953:Diagnosis-Related Groups; D005260:Female; D006302:Health Services Research / Q000379:methods; D006761:Hospitals / Q000145:classification / Q000592:standards* / Q000706:statistics & numerical data; D006801:Humans; D007049:Iatrogenic Disease / Q000453:epidemiology*; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008485:Medical Audit / Q000379:methods; D019300:Medical Errors / Q000706:statistics & numerical data*; D008499:Medical Records; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods* / Q000706:statistics & numerical data; D012107:Research Design; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology