Geographic variability in patient characteristics, treatment and outcome in an International Trial of Magnesium in acute myocardial infarction.
BACKGROUND
The interpretation of clinical trials and efforts directed at reducing the worldwide burden of coronary disease must take regional differences into account. This study examined the regional differences in baseline characteristics, treatment, and outcome in patients presenting with ST elevation myocardial infarction (STEMI) who were entered into the Magnesium in Coronaries (MAGIC) trial.


RESULTS
MAGIC randomized 6213 patients to standard care with either placebo infusion or infusion of intravenous magnesium sulphate. There was no difference in mortality between these groups. For this analysis, three geographic regions were identified (Region 1=United States and Canada; Region 2=Bulgaria, Georgia, and Russia; Region 3=Austria, Belgium, Chile, Hungary, Israel, the Netherlands, New Zealand, and Venezuela) and compared with respect to baseline characteristics, treatment, and 30-day mortality. Patients in Region 2 had the highest prevalence of adverse risk factors at entry, including history of prior myocardial infarction, heart failure, stroke, and hypertension; anterior location of index acute myocardial infarction; and presence of pulmonary congestion at presentation. Furthermore, Region 2 patients infrequently received reperfusion therapy compared with those in Region 1. Region 3 was intermediate in this regard. Mortality was highest in Region 2, least in Region 1, and intermediate in Region 3.


CONCLUSIONS
Geographic location, particularly, parts of Eastern Europe, is strongly and independently associated with mortality following STEMI. This geographic variation in mortality confirms prior reports, although adequate explanations continue to be elusive and are beyond the scope of this large simple trial. Future international trials must recognize this variation in design, analysis, and interpretation.
Domanski
Michael
M
The Clinical Trials Group, National Heart, Lung, and Blood Institute, 6701 Rockledge Drive, MSC 7936, Bethesda, MD 20892, USA. domanskm@nhlbi.nih.gov
Antman
Elliott M
EM
McKinlay
Sonja
S
Varshavsky
Sergei
S
Platonov
Pyotr
P
Assmann
Susan F
SF
Norman
James
J
D000368:Aged; D017130:Angioplasty; D002121:Calcium Channel Blockers / Q000627:therapeutic use*; D003710:Demography; D005260:Female; D005343:Fibrinolytic Agents / Q000627:therapeutic use; D006333:Heart Failure / Q000453:epidemiology; D006801:Humans; D006973:Hypertension / Q000453:epidemiology; D015994:Incidence; D038622:Internationality; D008278:Magnesium Sulfate / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000401:mortality / Q000601:surgery; D015995:Prevalence; D016032:Randomized Controlled Trials as Topic; D020521:Stroke / Q000453:epidemiology; D016896:Treatment Outcome
D002121:Calcium Channel Blockers; D005343:Fibrinolytic Agents; D008278:Magnesium Sulfate