EMS Services Underused by STEMI Patients

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Patients with ST-segment elevation myocardial infarction (STEMI) who use emergency medical services (EMS) to get to the hospital experience substantially reduced ischemic time and time to treatment. Unfortunately, according to results published online June 20, 2011, ahead of print in Circulation, 2 out of every 5 STEMI patients arrive without the aid of EMS, resulting in significant treatment delays.

Researchers led by Robin Mathews, MD, of the Duke University Medical Center (Durham, NC), performed an observational analysis of 37,634 STEMI patients treated at 372 US hospitals participating in the National Cardiovascular Data Registry Acute Coronary Treatment and Intervention Outcomes Network Registry-Get With the Guidelines between January 2007 and September 2009.

Age, Distance Key Factors in EMS Activation

Forty percent of the patients (n = 15,049) did not use EMS for transport to the hospital. Patients who did use EMS were more frequently older and women, while those who self-transported were more likely to be Hispanic. Those who arrived via EMS were also more likely to have comorbid conditions such as a history of MI, PCI, heart failure, or stroke, and more often lived farther from the hospital than those who self-transported (median distance 6.9 miles vs. 5.5 miles). However, there was no distinction between patients from urban vs. rural areas. Among patients who used EMS, 43% received a diagnostic ECG prior to hospital arrival.

After multivariable adjustment, age was the strongest sociodemograhic factor associated with EMS transport, followed by greater geographic distance from home to hospital. Male patients were less likely to activate EMS. Although Hispanic ethnicity was associated with less EMS use, the overall association with race was not as strong. Those with private insurance were least likely to use EMS compared with patients with government-funded or no insurance (table 1).

Table 1. Independent Sociodemographic Predictors Associated with EMS Transport

Neighborhood education and income levels, however, were not significantly associated with EMS activation.

Self-transported patients experienced longer median delays to care compared with their EMS-transported counterparts. For instance, patients who used EMS arrived at the hospital more than 30 minutes earlier following symptom onset than those who self-transported (table 2).

Table 2. Time to Care Processes by Transport Status

^a Among all patients undergoing primary PCI.
^b Among all patients undergoing fibrinolytic therapy.

“Our study finds a persistent underuse of EMS transport among a contemporary cohort of STEMI patients, . . .” the authors conclude. “The reasons for the persistence of this finding are not entirely clear, but cost, fear of false alarm, reluctance to bother or burden the medical community, lack of EMS benefit awareness, and other psychosocial factors, such as lack of trust in others, have been implicated.”

For instance, Dr. Mathews and colleagues noted that in areas without publically funded EMS, the cost can range from $390 to $900 for ambulance transport, potentially making insurance status a loose surrogate for the economic hardship associated with paying for such services.

Closer Does Not Equal Faster

And in terms of distance from the hospital, “those who lived closer were less likely to engage EMS, which I think comes from a perception that ‘if I live close by, I can get there faster,’” Dr. Mathews told TCTMD in a telephone interview, adding that this turned out to be a misperception. “If you arrive via EMS and the paramedics see you in your house, they’re able to start assessing you and treating you at that time, which really does expedite the rest of the triaging and treatment system. Treatment really does start prior to getting to the hospital.”

Dr. Mathews expressed surprise that the percentage of patients activating EMS—which typically means calling 911—was so low in a contemporary cohort, and noted that the study results are likely to translate to worse clinical outcomes for such individuals. “There’s not any doubt in the cardiology community that faster treatment time in the setting of STEMI is associated with improved clinical hard outcomes,” he said.

Previous Education Efforts Spotty

Dr. Mathews added that over the years communitywide educational efforts have resulted in short-term increases in EMS use, but these are often short-lived. “You have a waning effect, and over time patterns go back to what they were before the campaign,” he said. “You need to get professional societies and other large organizations to really endorse better education along the lines of what the American Heart Association is doing with its Mission Lifeline initiative.”

In particular, according to the paper, community education is needed to raise public awareness regarding the benefits of EMS. For instance, the availability of prehospital ECGs with EMS enables a more efficient triage process and delivery of reperfusion than does self-transport, the researchers say.

A positive aspect of this issue, Dr. Mathews noted, is that effective EMS systems are already in place. “It’s not that we don’t realize that we need an early triage system or that EMS isn’t important. We know those things, and we’ve created a good system to get people from their homes and triage them and get them treatment sooner,” he said. “Slowly over time, we should get there. This is really the low hanging fruit.”

 

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Source:
Mathews R, Peterson ED, Li S, et al. Use of emergency medical service transport among patients with ST-segment-elevation myocardial infarction: Findings from the National Cardiovascular Data Registry Acute Coronary Treatment and Intervention Outcomes Network Registry-Get With the Guidelines. Circulation. 2011;Epub ahead of print.

 

 

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