Factors Responsible for Improvement in Survival After NSTEMI
Are temporal improvements in 180-day mortality between 2003 and 2013 associated with changes in patients’ baseline clinical risk of use of guideline-indicated treatments for management of non–ST-elevation myocardial infarction (NSTEMI) among patients in the United Kingdom National Health Service?
This was a prospective observational cohort study of patients with NSTEMI in 247 hospitals in England and Wales. Data were analyzed from the Myocardial Ischemia National Audit Project (MINAP), a comprehensive clinical database of patients hospitalized with acute myocardial infarction and mandated by the Department of Health for all hospitals in England and Wales. The authors determined associations between baseline clinical risk (as based on demographics, GRACE risk score, comorbidities, etc.) and guideline-indicated treatments (pharmacotherapy or revascularization) and adjusted all-cause 180-day post-discharge mortality time.
Among 389,057 patients with NSTEMI, there were 113,586 deaths (29.2%). From 2003-2004 to 2012-2013, proportions with intermediate to high GRACE risk decreased (87.2% vs. 82.0%); proportions with the lowest risk increased (4.2% vs. 7.6%; p = 0.01 for trend). Unadjusted all-cause mortality rates at 180 days decreased from 10.8% to 7.6% (unadjusted hazard ratio, 0.968; 95% confidence interval, 0.966-0.971). These findings were not significantly changed when adjusted by baseline GRACE risk score, sex and socioeconomic status, comorbidities, and pharmacological therapies. The direction of association was reversed, however, after adjusting for use of an invasive coronary strategy (hazard ratio, 1.02; 95% confidence interval, 1.01-1.03).
Among nearly 400,000 patients with NSTEMI hospitalized between 2003 and 2013 in England and Wales, improvements in survival were associated with use of an invasive coronary strategy. However, temporal reduction in baseline acute coronary syndrome risk, increase in comorbidities, and use of guideline-indicated pharmacological therapies did not explain/contribute to gains in survival.
This is an interesting study that adds multiple insights to the literature. It is interesting to note that the temporal reduction in baseline acute coronary syndrome risk profile of patients with NSTEMI does not explain the gains in post-hospital discharge. Regarding pharmacotherapy, the authors caution that their findings “should not be interpreted to indicate that medical therapies have no role in management of NSTEMI.” Individual medication classes had a significant association with improved survival. Last, it is worthy to note that the majority of patients were at intermediate to high risk of death at 180 days. However, fewer than half of those with NSTEMI underwent coronary angiography. As the authors opine, “This finding is in keeping with the well-known risk-treatment paradox whereby the highest frequency of treatments were seen among patients in the lower risk category.”
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