Clinical prognosis, pre-existing conditions and the use of reperfusion therapy for patients with ST segment elevation acute myocardial infarction.
BACKGROUND
Some evidence-based therapies are underused in patients with a poor prognosis despite the fact that the survival gains would be highest among such patient subgroups. The extent to which this applies for acute, life-saving therapies is unknown. The impact of prognostic characteristics and pre-existing conditions on the use of reperfusion therapy among eligible patients with acute ST segment elevation myocardial infarction is examined.


METHODS
Of 2829 acute myocardial infarction patients prospectively identified in 53 acute care hospitals across Ontario, 987 presented with ST segment elevation within 12 h of symptom onset and without any absolute contraindications to reperfusion therapy. The baseline prognosis for each patient was derived from a validated risk-adjustment model of 30-day mortality. Multiple logistical regression was used to examine the relationships among reperfusion therapy, prognosis and the number of pre-existing chronic conditions after adjusting for factors such as age, sex, time since symptom onset and socioeconomic status.


RESULTS
Of the 987 appropriate candidates, 725 (73.5%) received reperfusion therapy (70.8% fibrinolysis, 2.6% primary angioplasty). The adjusted odds ratio of reperfusion therapy fell 4% with each 1% increase in baseline risk of death (adjusted OR 0.96, 95% CI 0.92 to 1.00, P=0.04) and fell 18% with each additional pre-existing condition (adjusted OR 0.82, 95% CI 0.76 to 0.90, P<0.001). The number rather than the type of pre-existing conditions inversely correlated with the use of reperfusion therapy. While the impact of baseline risk and pre-existing conditions was additive, pre-existing conditions exerted a greater impact on the nonuse of reperfusion therapy than did baseline risk.


CONCLUSIONS
A treatment-risk paradox is demonstrable even within a cohort of lower risk patients with ST segment elevation myocardial infarction. These findings are consistent with the view that these clinical decisions are more likely to be attributable to concerns about patient frailty or side effects than to a misunderstanding of treatment benefits.
Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada.
Andrea B
AB
Parker
C David
CD
Naylor
Alice
A
Chong
David A
DA
Alter
D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects; D015331:Cohort Studies; D019317:Evidence-Based Medicine; D005343:Fibrinolytic Agents / Q000009:adverse effects; D017052:Hospital Mortality; D006801:Humans; D016015:Logistic Models; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000453:epidemiology / Q000401:mortality / Q000628:therapy*; D015425:Myocardial Reperfusion / Q000379:methods*; D009864:Ontario / Q000453:epidemiology; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors; D016019:Survival Analysis; D016896:Treatment Outcome
D005343:Fibrinolytic Agents