Patients evaluated for chest pain in busier emergency departments experience lower rates of death or hospitalization for acute coronary syndrome (ACS) at both 30 days and one year, according to a study published Oct. 23 in Circulation: Cardiovascular Quality and Outcomes.
But patient volume only mattered to a certain point, noted lead author Dennis T. Ko, MD, and colleagues—once a center evaluated at least 1,400 patients for chest pain annually, a higher patient load wasn’t associated with additional improvements in outcomes.
The researchers said this was an important area to study because plausible explanations can be made for high-volume EDs having either better or worse outcomes. For example, high-volume EDs may have homed in on more appropriate patient selection for discharge but they also may be subject to overcrowding, which could lengthen the time until diagnosis or treatment and result in worse outcomes.
However, when studying almost 500,000 patients who presented with chest pain to EDs in Ontario, Canada, from 2008 to 2014, Ko et al. found high-volume centers were associated with better outcomes.
Compared to the lowest-quartile patient volumes, the highest-quartile EDs had lower unadjusted rates of death or hospitalization for ACS at 30 days (0.8 percent versus 1.0 percent) and one year (3.1 percent versus 4.4 percent). When patient volume was analyzed as a continuous variable, each one-log increase in volume was associated with a multivariate-adjusted 13 percent decrease in ACS or death at 30 days and an 8 percent decrease in that composite outcome at one year.
“Although the absolute difference in event rates was small at 30 days across ED volume categories, the magnitude of difference diverged over time such that a 1.3% difference in death or ACS was observed comparing the low and high-volume EDs at 1 year,” wrote Ko, with the Institute for Clinical Evaluative Sciences in Toronto, and colleagues. “The association was consistent among patients at different baseline risks, those discharged from rural or urban hospitals, and across all the endpoints.”
The researchers speculated increased specialist involvement was one of the reasons for the improved outcomes at higher-volume chest pain facilities. Indeed, the highest-volume EDs had cardiologist consultations in 47.6 percent of emergency room visits, while low-volume centers had cardiologist involvement in 26.7 percent of cases. Other differences in care processes between high- and low-volume centers included:
- Follow-up care from a cardiologist within 30 days was more likely in a high-volume ED (61.8 percent) versus a low-volume one (35.4 percent). Primary care physicians were more likely to see patients in follow-up visits to low-volume centers, suggesting they were replacing at least some of the cardiologist consultations.
- Echocardiography and stress testing were used after discharge in 16.5 percent and 29.1 percent of patients, respectively, in high-volume centers—almost double the rates seen in low-volume centers (8.6 percent and 16.1 percent).
- Patients evaluated at the busiest EDs were more likely to receive prescriptions within 30 days for angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (28.1 percent versus 25.4 percent), beta-blockers (19.5 percent versus 18.6 percent) and statins (26.4 percent versus 23.6 percent).
“It is possible that initial cardiology consultations in higher volume EDs enabled the outpatient referral process and engagement for patients for ambulatory testing and treatment after discharge,” Ko and coauthors wrote. “In contrast, primary care physicians evaluating patients after ED discharge without initial specialist consultation may be falsely reassured about the negative ED workup, are unaware of the need to perform additional diagnostic testing, and potentially have inadequate access of obtaining outpatient specialist care or diagnostic testing.”
The patients in the study were 59 years old on average, 46.7 percent men and 21.4 percent had myocardial infarction. The median number of patients treated annually in low-volume and high-volume centers, respectively, was 449 and 2,651. Although this study highlighted an important association between chest pain volumes and patient outcomes, “simply changing ED volume without improving access to specialist care or diagnostic testing is unlikely to improve process of care and outcomes,” the authors wrote.
Because many smaller EDs operate in remote areas, Ko et al. speculated it wouldn’t be possible to completely regionalize care for chest pain. Rather, they said partnerships with specialists from larger centers could facilitate e-consultations or telemedicine visits and streamline processes to get certain at-risk patients more extensive medical testing or cardiology care.
“Although we await further studies to understand the potential cost implication of more intensive care for these patients, a system to monitor access of cardiac evaluation after ED evaluation would be beneficial to ensure equity of care,” the authors wrote.