Emergency Department Chest Pain Volume Impacts Patient Outcomes Emergency Department Volume and Outcomes for Patients After Chest Pain Assessment

A study published in Circulation showed that the evaluation of chest pain in emergency departments with higher chest pain volume had lower rates of death or hospitalization for patients with acute coronary syndrome after discharge. The primary investigator, Dr. Dennis T. Ko and his colleagues also found that past a certain volume threshold, a rise in volume was not associated with any reduction in outcomes.

Chest pain is one of the most common symptoms of visits to the emergency department, in developed nations. It has not been demonstrated whether chest pain volume in emergency departments is important. Moreover, the relationship between chest pain volume and reduction of outcomes had not been established. In order to answer these questions, Ko and his colleagues conducted a study using population-based data of close to 500 000 patients ≥40 years old, presenting to ED in Ontario, Canada from 2008 to 2014, with chest pain, who were discharged after assessment. The processes of care after discharge from ED were evaluated. The primary outcome was a composite of all-cause death or hospitalization for acute coronary syndrome. Hierarchical logistic regression models adjusting for potential confounding variables were used to evaluate the association of annual ED chest pain volume and outcomes. The investigators also strived to determine if there was a volume threshold above which an increased ED volume was not associated with a lower adverse outcome. The mean age of the patients was 59 years, 46.7% were men, and 20% had diabetes mellitus. Patients discharged from higher volume EDs had higher rates of cardiologist consultations, cardiac medication use, and cardiac testing within 30 days of ED assessment. Higher ED volume was associated with significantly lower adjusted odds ratio for mortality or acute coronary syndrome (odds ratio, 0.87; 95% CI, 0.82–0.92 per each unit increase in the log of volume) at 30 days and at 1 year (odds ratio, 0.92; 95% CI, 0.88–0.92). Once the annual ED chest pain volume reached 1400 cases (95% CI, 910–1900), an increase of annual chest pain volume of 100 was associated with a relative decrease in the odds of the composite outcome at 30 days of <1%.

The investigators concluded that higher emergency department volume of patients with chest pain was associated with lower odds of dying or having a recurrent acute coronary syndrome. Moreover, at a certain volume threshold, an increase in volume was no longer associated with reduced outcomes. However, they emphasized that additional studies were needed to examine reasons for the discrepancies of outcomes in high- and low-volume emergency departments. Ko and his colleagues wrote, “These findings extend our current knowledge about the potential impact of ED volume on patient outcomes in contemporary clinical practice because only limited literature exists. A study from 2006 found that higher ED volumes were associated with a lower likelihood of missed myocardial infarction. It was conducted before the widespread use of troponin, and the outcomes difference was thought to be related to the lack of access to troponin assays in smaller volume EDs. Kocher et al. found lower in-hospital mortality among the 8 most commonly hospitalized conditions in the United States when patients were admitted from higher volume EDs. However, it was difficult to disentangle the impact of ED volume and hospital volume because they were highly correlated.”

Highlighting the reasons for the difficulty in fully disentangling the reasons why patients with chest pain evaluated in high-volume EDs had better outcomes, they stated, “ First, 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. 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 the need to perform additional diagnostic testing, and potentially have inadequate access of obtaining outpatient specialist care or diagnostic testing. Indeed, we found higher rates of cardiac medication prescriptions, cardiac catheterization use within 30 days, and almost a 2-fold higher rate of echocardiography, ischemic evaluation, and cardiologist visits comparing high-volume EDs verses and low volume EDs. Other reasons to explain the discrepancy in specialist follow-up included differences in discharge planning across EDs and regional difference in access to specialist care after discharge. Second, given the fact that a large proportion of patients evaluated in low volume ED resided in rural areas, we were uncertain whether this volume-outcome relationship could simply be explained by differences in geographic access. Accordingly, we performed an additional analysis that focused on patients in the urban area and found similar finding that higher volume EDs were associated with better outcomes.” Speaking of the importance of the study and future implications, they noted, “Our findings have policy implications on how best to manage patients with chest pain in the future. Although further studies are awaited 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.”