Ambulance diversion, which occurs when a hospital emergency department (ED) is temporarily closed to incoming ambulance traffic, is an important system-level interruption that causes delays in treatment and potentially lower quality of care. There is little empirical evidence investigating the mechanisms through which ambulance diversion might affect patient outcomes. We investigated whether ambulance diversion affects access to technology, likelihood of treatment, and ultimately health outcomes for Medicare patients with acute myocardial infarction in twenty-six California counties. We found that patients whose nearest hospital ED had significant ambulance diversions experienced reduced access to hospitals with cardiac technology. This led to a 4.6 percent decreased likelihood of revascularization and a 9.8 percent increase in one-year mortality compared to patients who did not experience diversion. Policy makers may wish to consider creating a policy to specifically manage certain time-sensitive conditions that require technological intervention during periods of ambulance diversion.

Background

Patients with ST-elevation myocardial infarction (STEMI) require timely reperfusion, and percutaneous coronary intervention (PCI) decreases morbidity and mortality. Regionalization of STEMI care has increased timeliness and use of PCI, but it is unknown whether benefits to regionalization depend on a community's distance from its nearest PCI center. We sought to determine whether STEMI regionalization benefits, measured by access to PCI centers, timeliness of treatment (same-day or in-hospital PCI), and mortality, differ by baseline distance to nearest PCI center.

Methods

Using a difference-in-difference-in-differences model, we examined access to PCI-capable hospitals, receipt of PCI either on the day of admission or during the care episode, and health outcomes for patients hospitalized from January 1, 2006, to September 30, 2015.

Results

Of 139,408 patients (2006 to 2015), 51% could reach the nearest PCI center in <30 minutes, and 49% required ≥30 minutes driving time. For communities with baseline access ≥30 minutes, regionalization increased the probability of admission to a PCI-capable hospital by 9.4% and also increased the likelihood of receiving same-day PCI (by 11.2%) and PCI during the hospitalization (by 7.4%). Patients living within 30 minutes did not accrue significant benefits (measured by admission to a PCI-capable hospital or receipt of PCI) from regionalization initiatives. Regionalization more than halved access disparities and completely eliminated treatment disparities between communities ≥30 minutes and communities <30 minutes from the nearest PCI hospital.

Conclusions

Measured by likelihood of admission to a PCI-capable facility and receipt of PCI, benefits of STEMI regionalization in California accrued only to patients whose nearest PCI center was ≥30 minutes away. We found no mortality benefits of regionalization based on distance from PCI center. Our results suggest that policymakers focus STEMI regionalization efforts in communities that are not already well serviced by PCI-capable hospitals.

Objective

To determine how access to percutaneous coronary intervention (PCI) is distributed across demographics.

Data sources

Secondary data from the 2011 American Hospital Association (AHA) survey data combined with 2010 Census.

Study design

We calculated prehospital times from 32,370 ZIP codes to the nearest PCI center. We used a multivariate logit model to determine the odds of untimely access by the ZIP code's concentration of vulnerable populations.

Data collection

We used ZIP code-level data on community characteristics from the 2010 Census and supplemented it with 2011 AHA survey data on service-line availability of PCI for responding hospitals.

Principal findings

For approximately 306 million Americans, the median prehospital time to the nearest PCI center is 33 minutes. While 84 percent of Americans live within one hour of a PCI center, the odds of untimely access are higher in low-income (OR: 3.00; 95 percent CI: 2.39, 3.77), rural (8.10; 95 percent CI: 6.84, 9.59), and highly Hispanic communities (2.55; 95 percent CI: 1.86, 3.49).

Conclusions

While the majority of Americans live within 60 minutes of a PCI center, rural, low-income, and highly Hispanic communities have worse PCI access. This may translate into worse outcomes for patients with acute myocardial infarction.

Objective

We investigated the association between crowding as measured by ambulance diversion and differences in access, treatment and outcomes between black and white patients.

Design

Retrospective analysis.

Setting

We linked daily ambulance diversion logs from 26 California counties between 2001 and 2011 to Medicare patient records with acute myocardial infarction and categorised patients according to hours in diversion status for their nearest emergency departments on their day of admission: 0, <6, 6 to <12 and ≥ 12 h. We compared the amount of diversion time between hospitals serving high volume of black patients and other hospitals. We then use multivariate models to analyse changes in outcomes when patients faced different levels of diversion, and compared that change between black and white patients.

Participants

29,939 Medicare patients from 26 California counties between 2001 and 2011.

Main outcome measures

(1) Access to hospitals with cardiac technology; (2) treatment received; and (3) health outcomes (30-day, 90-day, and 1-year death and 30-day readmission).

Results

Hospitals serving high volume of black patients spent more hours in diversion status compared with other hospitals. Patients faced with the highest level of diversion had the lowest probability of being admitted to hospitals with cardiac technology compared with those facing no diversion, by 4.4% for cardiac care intensive unit, and 3.4% for catheterisation laboratory and coronary artery bypass graft facilities. Patients experiencing increased diversion also had a 4.3% decreased likelihood of receiving catheterisation and 9.6% higher 1-year mortality.

Conclusions

Hospitals serving high volume of black patients are more likely to be on diversion, and diversion is associated with poorer access to cardiac technology, lower probability of receiving revascularisation and worse long-term mortality outcomes.

High-occupancy hospitals may be sensitive to neighboring emergency department (ED) closures and openings, as they already operate at or near capacity. We conducted a retrospective analysis using data for the period 2001-13 to examine outcomes of and treatment received by patients with acute myocardial infarction at so-called bystander EDs that had been exposed to nearby ED closures or openings. We used changes in driving time between an ED and the next-closest one as a proxy for a closure or opening: If driving time increased, for instance, it meant that a nearby ED had closed. When a high-occupancy ED was exposed to a closure that resulted in increased driving time of thirty minutes or more to the next-closest ED, one-year mortality and thirty-day readmission rates increased by 2.39 and 2.00 percentage points, respectively, while the likelihood of receiving percutaneous coronary intervention (PCI) declined by 2.06 percentage points. Exposure to ED openings that resulted in decreased driving times of thirty minutes or more was associated with reductions in thirty-day mortality at bystander hospitals and an increased likelihood of receiving PCI. Our findings suggest that limited resources at high-occupancy bystander hospitals make them sensitive to changes in the availability of emergency care in neighboring communities.

Background Racially and ethnically minoritized groups, people with lower income, and rural communities have worse access to percutaneous coronary intervention (PCI) than their counterparts, but PCI hospitals have preferentially opened in wealthier areas. Our study analyzed disparities in PCI access, treatment, and outcomes for patients with acute myocardial infarction based on the census-derived Area Deprivation Index. Methods and Results We obtained patient-level data on 629 419 patients with acute myocardial infarction in California between January 1, 2006 and December 31, 2020. We linked patient data with population characteristics and geographic coordinates, and categorized communities into 5 groups based on the share of the population in low or high Area Deprivation Index neighborhoods to identify differences in PCI access, treatment, and outcomes based on community status. Risk-adjusted models showed that patients in the most advantaged communities had 20% and 15% greater likelihoods of receiving same-day PCI and PCI during the hospitalization, respectively, compared with patients in the most disadvantaged communities. Patients in the most advantaged communities also had 19% and 16% lower 30-day and 1-year mortality rates, respectively, compared with the most disadvantaged, and a 15% lower 30-day readmission rate. No statistically significant differences in admission to a PCI hospital were observed between communities. Conclusions Patients in disadvantaged communities had lower chances of receiving timely PCI and a greater risk of mortality and readmission compared with those in more advantaged communities. These findings suggest a need for targeted interventions to influence where cardiac services exist and who has access to them.

BACKGROUND: Disparities in access to percutaneous coronary intervention (PCI) for patients with acute myocardial infarction may result from openings and closures of PCI-providing hospitals, potentially leading to low hospital PCI volume, which is associated with poor outcomes. OBJECTIVES: The authors sought to determine whether openings and closures of PCI hospitals have differentially impacted patient health outcomes in high- vs average-capacity PCI markets. METHODS: In this retrospective cohort study, the authors identified PCI hospital availability within a 15-minute driving time of zip code communities. The authors categorized communities by baseline PCI capacity and identified changes in outcomes associated with PCI-providing hospital openings and closures using community fixed-effects regression models. RESULTS: From 2006 to 2017, 20% and 16% of patients in average- and high-capacity markets, respectively, experienced a PCI hospital opening within a 15-minute drive. In average-capacity markets, openings were associated with a 2.6 percentage point decrease in admission to a high-volume PCI facility; high-capacity markets saw an 11.6 percentage point decrease. After an opening, patients in average-capacity markets experienced a 5.5% and 7.6% relative increase in likelihood of same-day and in-hospital revascularization, respectively, as well as a 2.5% decrease in mortality. PCI hospital closures were associated with a 10.4% relative increase in admission to high-volume PCI hospitals and a 1.4 percentage point decrease in receipt of same-day PCI. There was no change observed in high-capacity PCI markets. CONCLUSIONS: After openings, patients in average-capacity markets derived significant benefits, whereas those in high-capacity markets did not. This suggests that past a certain threshold, facility opening does not improve access and health outcomes.

This study investigated whether emergency department crowding affects blacks more than their white counterparts and the mechanisms behind which this might occur. Using a nonpublic database of patients in California with acute myocardial infarction between 2001 and 2011 and hospital-level data on ambulance diversion, we found that hospitals treating a high share of black patients with acute myocardial infarction were more likely to experience diversion and that black patients fared worse compared to white patients experiencing the same level of emergency department crowding as measured by ambulance diversion. The ninety-day and one-year mortality rates among blacks exposed to high diversion levels were 2.88 and 3.09 percentage points higher, respectively, relative to whites, representing a relative increase of 19 percent and 14 percent for ninety-day and one-year death, respectively. Interventions that decrease the need for diversion in hospitals serving a high volume of blacks could reduce these disparities.

Inpatient volume has long been believed to be a contributing factor to ambulance diversion, which can lead to delayed treatment and poorer outcomes. We examined the extent to which both daily inpatient and emergency department (ED) volumes at specified hospitals, and diversion levels (that is, the number of hours ambulances were diverted on a given day) at their nearest neighboring hospitals, were associated with diversion levels in the period 2005-12. We found that a 10 percent increase in patient volume was associated with a sevenfold greater increase in diversion hours when the volume increase occurred among inpatients (5 percent) versus ED visitors (0.7 percent). When the next-closest ED experienced mild, moderate, or severe diversion, the study hospital's diversion hours increased by 8 percent, 23 percent, and 44 percent, respectively. These findings suggest that efforts focused on managing inpatient volume and flow might reduce diversion more effectively than interventions focused only on ED dynamics.

Background

Regionalization of ST-segment elevation myocardial infarction (STEMI) systems of care has been championed over the past decade. Although timely access to percutaneous coronary intervention (PCI) has been shown to improve outcomes, no studies have determined how regionalization has affected the care and outcomes of patients. We sought to determine if STEMI regionalization is associated with changes in access, treatment, and outcomes.

Methods

Using a difference-in-differences approach, we analyzed a statewide, administrative database of 139 494 patients with STEMI in California from 2006 to 2015 using regionalization data based on a survey of all local Emergency Medical Services agencies in the state.

Results

For patients with STEMI, the base rate of admission to a hospital with PCI capability was 72.7%, and regionalization was associated with an increase of 5.34 percentage points (95% CI, 1.58-9.10), representing a 7.1% increase. Regionalization was also associated with a statistically significant increase of 3.54 (95% CI, 0.61-6.48) percentage points in the probability of same-day PCI, representing an increase of 7.1% from the 49.7% base rate and a 4.6% relative increase (2.97 percentage points [95% CI, 0.1-5.85]) in the probability of receiving PCI at any time during the hospitalization. There was a 1.84 percentage point decrease (95% CI, -3.31 to -0.37) in the probability of receiving fibrinolytics. For 7-day mortality, regionalization was associated with a 0.53 (95% CI, -1 to -0.06) percentage point greater reduction (representing 5.8% off the base rate of 9.1%) and a 1.75 percentage point decrease in the likelihood of all-cause 30-day readmission (95% CI, -3.39 to -0.11; representing 6.4% off the base rate of 27.4%). No differences were found in longer-term mortality.

Conclusions

Among patients with STEMI in California from 2006 to 2015, STEMI regionalization was associated with increased access to a PCI-capable hospital, greater use of PCI, lower 7-day mortality, and lower 30-day readmissions.