Are international differences in the outcomes of acute coronary syndromes apparent or real? A multilevel analysis.
OBJECTIVE
International variation in the outcomes of patients with acute coronary syndromes (ACS) has been well reported. The relative contributions of patient, hospital, and country level factors on clinical outcomes, however, remain unclear, and thus, was the objective of this study.


METHODS
Multilevel logistic regression models were developed for death/(re)infarction (MI) at 30 days and death in one year, with patients (1st level) nested in hospitals (2nd level) and hospitals in countries (3rd level).


METHODS
The GUSTO IV ACS clinical trial was carried out at 458 hospital sites in 24 countries.


METHODS
7800 non-ST segment elevation (NSTE) ACS patients.


RESULTS
There were substantial variations among countries in the processes and outcomes of care at 30 days, ranging from 5.4% to 50.0% for percutaneous coronary intervention, 4.3% to 21.2% for coronary artery bypass graft surgery, 5.0% to 13.9% for 30 day death/(re)MI, and 4.9% to 14.8% for one year mortality. However, the residual inter-country variations in 30 day death/(re)MI and one year mortality became non-significant and nearly disappeared (p > 0.500 for both) after adjusting for key baseline patient characteristics and hospital factors, which became significant (p < 0.01 for both). Patient level factors accounted for 96%-99% of total variation in these end points, leaving the remaining 1% and 4% of variance attributable to hospital level factors.


CONCLUSIONS
The international differences in clinical outcomes in this study of NSTE ACS are primarily accounted for by the patient level factors, with hospital level factors playing a minor part, and the country level factors a negligible one. These findings have significant policy and research implications involving international collaboration and comparisons.
Chang
Wei-Ching
WC
University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
Midodzi
William K
WK
Westerhout
Cynthia M
CM
Boersma
Eric
E
Cooper
Judith
J
Barnathan
Elliot S
ES
Simoons
Maarten L
ML
Wallentin
Lars
L
Ohman
E Magnus
EM
Armstrong
Paul W
PW
D000077284:Abciximab; D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal / Q000008:administration & dosage; D000925:Anticoagulants / Q000008:administration & dosage; D016757:Death, Sudden, Cardiac / Q000453:epidemiology; D014943:Global Health; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000008:administration & dosage; D008875:Middle Aged; D009203:Myocardial Infarction / Q000188:drug therapy / Q000401:mortality*; D009204:Myocardial Revascularization; D010818:Practice Patterns, Physicians'; D011379:Prognosis; D012008:Recurrence; D012044:Regression Analysis; D012111:Residence Characteristics
D000911:Antibodies, Monoclonal; D000925:Anticoagulants; D007140:Immunoglobulin Fab Fragments; D000077284:Abciximab