Meta-analysis Links Off-Hour Acute MI Presentation to Higher Mortality

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Patients who present with acute myocardial infarction (MI) at night or over the weekend have a higher risk of in-hospital and 30-day mortality. A likely contributor is the average 15-minute increase in door-to-balloon (D2B) time for STEMI, according to a meta-analysis published online January 21, 2014, ahead of print in the British Medical Journal.

Investigators led by Henry Ting, MD, MBA, of the Mayo Clinic (Rochester, MN), analyzed data from 48 international cohort studies conducted in North America, Europe, and elsewhere between 2001 and 2013. Controlling for different definitions of “off-hours” and subject-overlap, the researchers included nearly 1.9 million acute MI patients. Thirty of the included studies reported D2B times for approximately 70,000 STEMI patients.

Approximately 900,000 patients present with acute MI in the United States annually, with two-thirds of those occurring off-hours.

STEMI May Be Responsible

For acute MI patients as a whole, off-hour presentation was associated with higher mortality, whether in-hospital, at 30 days, or both (table 1).

Table 1. Acute MI: Risk of Mortality for Off- vs On-Hours Presentation

 

OR

95% CI

In-Hospital

1.05

1.03-1.08

At 30 Days

1.05

1.02-1.09

Combined

1.06

1.04-1.09


Compared with studies conducted in the United States, the relative increase in mortality was greater in studies conducted in Europe (OR 1.08; 95% CI 1.02-1.15) and other regions (OR 1.25; 95% CI 1.15-1.36).

A diagnosis of STEMI during off-hours correlated with an increased rate of both in-hospital and 30-day mortality (OR 1.12, 95% CI 1.03-1.22) compared with a non-STEMI diagnosis (OR 0.96; 95% CI 0.91-1.02). Moreover, off-hour STEMI presentation was associated with a decreased rate of receiving PCI within 90 minutes (OR 0.40; 95% CI 0.35-0.45) compared with regular-hour presentation, with an average increase in D2B of 14.8 minutes (95% CI 10.7-19.0 minutes).

Small Relative Odds Increases Result in Big Population Effects

Some previous studies have failed to find a mortality difference between regular and off-hour acute MI or STEMI presentation, the authors write, reporting that that theirs is the first systematic survey to consider a wide-range of data and sources. They postulate that the higher risk for off-hours patients could be due to a number of factors:

  • Delays in reperfusion
  • Lower number and level of expertise of available hospital staff
  • Lower likelihood of receiving evidenced-based treatment
  • Gaps in the quality of care

“Although the relative odds increase in off-hour mortality seems small, the implications at the population level may be substantial,” Dr. Tin and colleagues assert. They calculate that the absolute rates of in-hospital and 30-day mortality are increased by 0.4% and 0.6%, respectively, for off-hours acute MI presentation, translating into an annual excess of 2,300 deaths in-hospital and 3,800 at 30-days.

The authors indicate the effect of off-hours presentation appears stronger in the United States than elsewhere and to be worse in recent years than in the initial study year of 2001.

Standardization of care is necessary to reduce discrepancies, the researchers write. “Efforts to improve systems of care should ensure that comparable outcomes are achieved for patients regardless of the time of day or day of the week that patients present to the healthcare system.”

 


Source:
Sorita A, Ahmed A, Starr SR, et al. Off-hour presentation and outcomes in patients with acute myocardial infarction: systematic review and meta-analysis. BMJ. 2014;Epub ahead of print.

 

 

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Meta-analysis Links Off-Hour Acute MI Presentation to Higher Mortality

Patients who present with acute myocardial infarction (MI) at night or over the weekend have a higher risk of in-hospital and 30-day mortality. A likely contributor is the average 15-minute increase in door-to-balloon
Disclosures
  • Dr. Ting reports no relevant conflicts of interest.

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