Trends in five-year survival of patients discharged after acute myocardial infarction.
BACKGROUND
It has previously been shown that the increased use of therapeutic intervention may not reduce patient fatality if there is a simultaneous increase in case severity. The present study was designed to extend the relationship between case severity and therapeutic interventions to long-term survival in the same study population.


OBJECTIVE
To compare five-year survival of patients discharged after acute myocardial infarction from 1984 to 1988 and from 1989 to 1993, and to evaluate possible reasons for survival differences.


METHODS
The present study was population-based. Survival time was determined by record linkage into the Canadian Mortality Database. Association of five-year survival with patient characteristics, in-hospital treatment and discharge medications was assessed by logistical regression analysis. Case severity was calculated as the probability of death within five years, given the patient profile and excluding any interventions.


RESULTS
Between the two study periods, most patient characteristics and treatment intensity changed, but case severity for the study population remained constant. Five-year survival improved from 74.8% to 79.2% (P(chi2)=0.001). The improvement was adequately described by the combination of changes in patient profile and treatment without residual period effect (P(goodness-of-fit)=0.752). The treatments significantly associated with five-year survival were coronary artery bypass graft surgery (OR 2.74; 95% CI 1.86 to 4.05), percutaneous coronary intervention (OR 2.63; 95% CI 1.67 to 4.14) and thrombolysis (OR 1.98; 95% CI 1.50 to 2.62) during admission, as well as acetylsalicylic acid (OR 1.39; 95% CI 1.15 to 1.68) or beta-blocker (OR 1.60; 95% CI 1.34 to 1.92) prescription at discharge.


CONCLUSIONS
Changes in patient profile did not affect long-term prognosis; instead, treatment modalities accounted for the observed improvement in five-year survival.
Bata
Iqbal R
IR
Department of Medicine, Division of Cardiology, Dalhousie University, Halifax, Nova Scotia, Canada.
Gregor
Ronald D
RD
Wolf
Hermann K
HK
Brownell
Brenda
B
D000328:Adult; D017677:Age Distribution; D000368:Aged; D002423:Cause of Death; D015897:Comorbidity; D001026:Coronary Artery Bypass / Q000706:statistics & numerical data; D003920:Diabetes Mellitus / Q000453:epidemiology; D004562:Electrocardiography; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D006973:Hypertension / Q000453:epidemiology; D007902:Length of Stay / Q000706:statistics & numerical data; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000145:classification / Q000175:diagnosis / Q000401:mortality* / Q000628:therapy; D009674:Nova Scotia / Q000453:epidemiology; D010351:Patient Discharge / Q000706:statistics & numerical data*; D015995:Prevalence; D011379:Prognosis; D012720:Severity of Illness Index; D017678:Sex Distribution; D012769:Shock / Q000453:epidemiology; D012907:Smoking / Q000453:epidemiology; D016019:Survival Analysis