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BACKGROUND: Sex differences in acute myocardial infarction treatment and outcomes are well documented, but it is unclear whether differences are consistent across countries. The objective of this study was to investigate the epidemiology, use of interventional procedures, and outcomes for older females and males hospitalized with ST-segment–elevation myocardial infarction (STEMI) and non–ST-segment–elevation myocardial infarction (NSTEMI) in 6 diverse countries. METHODS: We conducted a serial cross-sectional cohort study of 1 508 205 adults aged ≥66 years hospitalized with STEMI and NSTEMI between 2011 and 2018 in the United States, Canada, England, the Netherlands, Taiwan, and Israel using administrative data. We compared females and males within each country with respect to age-standardized hospitalization rates, rates of cardiac catheterization, percutaneous coronary intervention, and coronary artery bypass graft surgery within 90 days of hospitalization, and 30-day age- and comorbidity-adjusted mortality. RESULTS: Hospitalization rates for STEMI and NSTEMI decreased between 2011 and 2018 in all countries, although the hospitalization rate ratio (rate in males/rate in females) increased in virtually all countries (eg, US STEMI ratio, 1.58:1 in 2011 and 1.73:1 in 2018; Israel NSTEMI ratio, 1.71:1 in 2011 and 2.11:1 in 2018). Rates of cardiac catheterization, percutaneous coronary intervention, and coronary artery bypass graft surgery were lower for females than males for STEMI in all countries and years (eg, US cardiac catheterization in 2018, 88.6% for females versus 91.5% for males; Israel percutaneous coronary intervention in 2018, 76.7% for females versus 84.8% for males) with similar findings for NSTEMI. Adjusted mortality for STEMI in 2018 was higher for females than males in 5 countries (the United States, Canada, the Netherlands, Israel, and Taiwan) but lower for females than males in 5 countries for NSTEMI. CONCLUSIONS: We observed a larger decline in acute myocardial infarction hospitalizations for females than males between 2011 and 2018. Females were less likely to receive cardiac interventions and had higher mortality after STEMI. Sex disparities seem to transcend borders, raising questions about the underlying causes and remedies. [ABSTRACT FROM AUTHOR]

BACKGROUND: Cumulative costs of transcatheter aortic valve replacement (TAVR) differ in the referral, procedural and postprocedural phases depending on patient comorbidities, type of procedure, and procedural complications. Our goal was to determine the association between neighborhood measures of social deprivation and TAVR costs in each of the 3 phases. METHODS: Demographics, patient comorbidities, procedural details, in-hospital complications, and costs for adults undergoing TAVR between 2017 and 2020 in Ontario, Canada were obtained from administrative databases and linked to social deprivation data using the Ontario Marginalization Index. The 3 dimensions of social deprivation assessed were (1) material deprivation, (2) residential instability, and (3) ethnic concentration. Hierarchical generalized linear models were used to determine the association between neighborhood social deprivation and cumulative TAVR costs, reported in 2018 Canadian dollars. RESULTS: We identified a total of 7617 TAVR referrals with 3784 patients undergoing TAVR within our study period. Cumulative mean costs in the referral, procedural and postprocedural phases were $8116±$11 374, $32 790±$17 766, and $18 901±$32 490, respectively. After adjustment for clinical and demographic variables, higher factor scores in residential instability were associated with greater cumulative costs in the postprocedural phase, whereas higher factor scores in the other 2 dimensions of marginalization were not significantly associated with higher costs in any of the 3 phases. CONCLUSIONS: This analysis shows that residential instability is associated with higher cumulative costs in the postprocedural phase of TAVR. This lays the foundation for future studies to understand the mechanism of this finding and identify potential mitigation policies. [ABSTRACT FROM AUTHOR]

Background: Clopidogrel is one of the most commonly prescribed medications because of its ability to improve clinical outcomes for a broad range of cardiovascular conditions. After patent protection expired for Plavix in 2012, many healthcare systems adopted generic clopidogrel as a strategy to reduce healthcare costs.Methods and Results: We conducted a population-based observational study to determine whether generic clopidogrel was noninferior to Plavix. Patients who were hospitalized with an acute coronary syndrome (ACS) from 2009 to 2014 in Ontario, Canada, >65 years, survived ≥7 days after discharge, were eligible for inclusion. The primary outcome was a composite of death and recurrent ACS at 1 year. The noninferiority margin was prespecified at a relative hazard difference of 10%. Inverse propensity of treatment weighting of the propensity score was used to account for differences in baseline characteristics between the treatment groups. The effect of clopidogrel on the hazard of clinical outcomes was estimated using a Cox proportional hazards model within the propensity-weighted cohort using Plavix as a reference. Our study included 24 530 patients with ACS, 12 643 were prescribed Plavix and 11  887 were prescribed generic clopidogrel at hospital discharge. The mean age was 77 years, 57% were men, and 21% had an ST-segment-elevation myocardial infarction. At 1 year, 17.6% of patients prescribed Plavix and 17.9% of patients prescribed clopidogrel experienced the primary outcome (hazard ratio, 1.02; 95% confidence interval, 0.96-1.08; P=0.005 for noninferiority). No significant differences between rates of death, all-cause readmission, ACS, stroke or transient ischemic attack, or bleeding were observed.Conclusions: Generic clopidogrel was noninferior to Plavix with respect to the composite end point of death and recurrent hospitalization for ACS at 1 year among adults >65 years after an ACS hospitalization. Our findings support generic clopidogrel in ACS, which could lead to substantial healthcare cost savings. [ABSTRACT FROM AUTHOR]

Background: The appropriate use criteria considers cardiac stress testing within 2 years after percutaneous coronary intervention (PCI) to be rarely appropriate, unless prompted by symptoms or change in clinical status. Little is known about the patterns of cardiac stress testing after PCI in the single-payer Canadian healthcare system, where mechanisms for reimbursement are different from the United States.Methods and Results: Frequency and timing of cardiac stress testing within 2 years of PCI performed between April 2004 and March 2013 in Ontario, Canada, was determined from linked provincial databases. Subsequent rates of coronary angiography and revascularization after stress testing were ascertained. Of the 112 691 patients with PCI, 67 442 (59.8%) underwent at least 1 stress test, with 38 267 (34.0%) undergoing repeat stress testing (ie, >1 stress test) within 2 years. Patients who underwent stress testing were younger, had less medical comorbidities, were more likely to reside in urban areas, and had higher incomes. Spikes in incidence of repeat stress testing were observed at 3 to 4 months, 6 to 7 months, and 12 to 13 months after the prior stress test. Of those tested, only 5.9% underwent subsequent coronary angiography, and only 3.1% underwent repeat revascularization within 60 days of stress testing.Conclusions: More than half of all patients undergo cardiac stress testing within 2 years of PCI, with one third undergoing repeat stress tests. Only 1 of 30 tested patients underwent repeat revascularization. These findings reinforce the appropriate use criteria recommendations against routine stress testing after PCI. Further work is needed to aid with the selection of patients most likely to benefit from stress testing after PCI. [ABSTRACT FROM AUTHOR]

Background: Depression is prevalent among patients with myocardial infarction and is associated with a worse prognosis. However, little is known about its importance in patients with chronic stable angina. We conducted a retrospective population-based cohort study to determine the occurrence and predictors of developing depression in patients with a new diagnosis of chronic stable angina. In addition, we sought to understand its impact on subsequent clinical outcomes.Methods and Results: Our cohort included patients in Ontario, Canada, with stable angina based on obstructive coronary artery disease found on angiogram. Depression was ascertained by physician billing codes and hospital admissions diagnostic codes. We first developed multivariable Cox proportional hazards models to determine predictors of developing depression. Clinical outcomes of interest included all-cause mortality, admission for myocardial infarction, and subsequent revascularization. Using hierarchical multivariable Cox proportional hazards models with occurrence of depression as a time-varying variable to control for potential immortal time bias, we evaluated the impact of depression on clinical outcomes. Our cohort consisted of 22 917 patients. The occurrence of depression after diagnosis of stable chronic angina was 18.8% over a mean follow-up of 1084 days. Predictors of depression included remote history of depression, female sex, and more symptomatic angina based on Canadian Cardiovascular Society class. Patients who developed depression had a higher risk of death (hazard ratio 1.83, 95% confidence interval 1.62-2.07) and admission for myocardial infarction (hazard ratio 1.36, 95% confidence interval 1.10-1.67) compared with nondepressed patients.Conclusions: Depression is common in patients with chronic stable angina and is associated with increased morbidity and mortality. [ABSTRACT FROM AUTHOR]

Background: Wide variation exists in the detection rate of obstructive coronary artery disease (CAD) with elective coronary angiography for suspected stable ischemic heart disease. We sought to understand the incremental impact of nonclinical factors on this variation. Methods and Results: We included all patients who underwent coronary angiography for possible suspected stable ischemic heart disease, from October 1, 2008, to September 30, 2011, in Ontario, Canada. Nonclinical factors of interest included physician self-referral for angiography, the physician type (invasive or interventional), and hospital type. Hospitals were categorized into diagnostic angiogram only centers, stand-alone percutaneous coronary intervention centers, or full service centers with coronary artery bypass surgery available. Multivariable hierarchical logistic models were developed to identify system and physician-level predictors of obstructive CAD, after adjustment for patient factors. Our cohort consisted of 60 986 patients, of whom 31 726 had obstructive CAD (52.0%), with significant range across hospitals from 37.3% to 69.2%. Fewer self-referral patients (49.8%) had obstructive CAD compared with nonself-referral patients (53.5%), with an odds ratio of 0.89 (95% confidence interval, 0.86-0.93; P<0.001). Angiograms performed by invasive physicians had a lower likelihood of obstructive CAD compared with those by interventional physicians (48.2% versus 56.9%; odds ratio, 0.85; 95% confidence interval, 0.81-0.90; P<0.001). Fewer angiograms at diagnostic only centers showed obstructive CAD (42.0%) compared with full service centers (55.1%; odds ratio, 0.62; 95% confidence interval, 0.39-0.98; P=0.04). Nonclinical factors accounted for 23.8% of the variation between hospitals. Conclusions: Physician and system factors are important predictors of obstructive CAD with coronary angiography. [ABSTRACT FROM AUTHOR]

Background: Ezetimibe use has steadily increased in Canada during the past decade even in the absence of evidence demonstrating a beneficial effect on clinical outcomes. Among the 4 most populated provinces in Canada, there is a gradient in the restrictiveness of ezetimibe in public-funded formularies (most to least strict: British Columbia, Alberta, Quebec, and Ontario). The effect of formulary policy on the use of ezetimibe over time is unknown.Methods and Results: We conducted a population-level cohort study using Intercontinental Marketing Services Health Canada's data from June 2003 to December 2012 to examine ezetimibe use in these 4 provinces to better understand the association between use and formulary restrictiveness. We found regional variations in the patterns of ezetimibe use. From June 2003 to December 2012, British Columbia (most restrictive) had the lowest monthly increasing rate from $261 to $21 926 ($190/100 000 population/mo), whereas Ontario (least restrictive) had the most rapid monthly increase from $223 to $74 030 ($ 647/100 000 population/mo), and Quebec from $130 to $59 690 ($522/100 000 population/mo) and Alberta from $356 to $ 37 604 ($327/100 000 population/mo) were intermediate (P<0.001).Conclusions: Ezetimibe use remains common, increasing during the past decade. Use steadily increased in provinces with the most lenient formularies. In contrast, use was lower, plateauing since 2008 in British Columbia and Alberta, which have more restrictive formularies. The gradient in ezetimibe use was related to variability in restrictiveness of the provincial formularies, illustrating the potential of a policy response gradient that may be used to more effectively manage medication use. [ABSTRACT FROM AUTHOR]

The article focuses on the impact of preprocedural statin therapy on patients with percutaneous coronary intervention (PCI), particularly on the risk for periprocedural myocardial infarction. In the study conducted by the authors, they observed 12,980 patients with stable coronary artery disease and who has undergone PCI. They revealed that preprocedural statins was effective within 90 days after PCI, but was no longer significant after a year of operation.

Background: Cardiac catheterization is substantially underused among higher-risk patients with acute myocardial infarction (AMI) with appropriate indications but overused among patients with inappropriate indications. We sought to determine the importance of anticipated benefit and anticipated harm on the use of cardiac catheterization among older patients with AMI.Methods and Results: We performed an analysis of Medicare fee-for-service beneficiaries hospitalized with an AMI between 1998 and 2001. Multivariate models were developed to determine relative importance of anticipated benefit (baseline cardiovascular risk), anticipated harm (bleeding risk, comorbidities), and demographic factors (age, sex, race, regional invasive intensity) in predicting cardiac catheterization use within 60 days of AMI admission. Analyses were stratified by American College of Cardiology/American Heart Association class I or II as appropriate, and class III as inappropriate. Determinants of reduced likelihood of cardiac catheterization among 42 241 AMI patients with appropriate indications included (in order of importance) older age (likelihood chi(2)=1309.5), higher bleeding risk score (likelihood chi(2)=471.2), more comorbidities (likelihood chi(2)=276.6), female sex (likelihood chi(2)=162.9), hospitalization in low (likelihood chi(2)=67.9) or intermediate intensity invasive regions (likelihood chi(2)=22.4) (all P<0.001), and baseline cardiovascular risk (likelihood chi(2)=6.4, P=0.01). Among 2398 AMI patients with inappropriate indications, significant determinants of greater procedure likelihood included younger age, male sex, lower bleeding risk score, and fewer comorbidities.Conclusions: Regardless of the procedure indication, the decision to perform cardiac catheterization in this population appears largely driven by demographic factors and potential harm rather than potential benefit of the procedure. [ABSTRACT FROM AUTHOR]

The article discusses a research on the use of percutaneous coronary intervention (PCI) to reduce mortality in patients with stable chronic angina, supported by the Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation study. It presents a summary of trials on PCI and suggests the lifesaving potential of PCI for patients with coronary artery disease. It also highlights the importance of distinguishing between stable versus unstable coronary artery disease patients to the evaluation of the possible benefit of PCI.

The article examines the effectiveness and safety of using sirolimus versus paclitaxel stents in reducing restenosis in diabetic and nondiabetic patients. The study found no difference in rates of target-vessel revascularization, myocardial infarction, or death. It also revealed the association of the use of sirolimus stents with a significantly lower 3-year rate of target-vessel revascularization in nondiabetic patients. The study noted the similar mortality rates among patients receiving paclitaxel and sirolimus stents.

Background: Stroke reduction with direct oral anticoagulants (DOACs) in atrial fibrillation (AF) is dependent on adherence and persistence in the real-world setting. Individual study estimates of DOAC adherence/persistence rates have been discordant. Our aims were to characterize real-world observational evidence for DOAC adherence/persistence and evaluate associated clinical outcomes in patients with AF.Methods and Results: PubMed, EMBASE, and CINAHL were searched from inception to June 2018. Observational studies that reported real-world DOAC adherence/persistence in patients with AF were included. Study quality was assessed using the Newcastle-Ottawa Scale. Meta-analyses for pooled estimates were performed using DerSimonian and Laird random-effects models. Outcomes included DOAC mean proportion of days covered or medication possession ratio, proportion of good adherence (proportion of days covered/medication possession ratio ≥80%), persistence, DOAC versus vitamin K antagonists persistence, and clinical outcomes associated with nonadherence/nonpersistence. Forty-eight observational studies with 594 784 unique patients with AF (59% male; mean age 71 years) were included. The overall pooled mean proportion of days covered/medication possession ratio was 77% (95% CI, 75%-80%), proportion of patients with good adherence was 66% (95% CI, 63%-70%), and proportion persistent was 69% (95% CI, 65%-72%). The pooled proportion of patients with good adherence was 71% (95% CI, 64%-78%) for apixaban, 60% (95% CI, 52%-68%) for dabigatran, and 70% (95% CI, 64%-75%) for rivaroxaban. Similar patterns were found for pooled persistence by agent. The pooled persistence was higher with DOACs than vitamin K antagonists (odds ratio, 1.44 [95% CI, 1.12-.86]). DOAC nonadherence was associated with an increased risk of stroke (hazard ratio, 1.39 [95% CI, 1.06-1.81]).Conclusions: Suboptimal adherence and persistence to DOACs was common in patients with AF, with 1 in 3 patients adhering to their DOAC <80% of the time, which was associated with poor clinical outcomes in nonadherent patients. Although it is convenient that DOACs do not require laboratory monitoring, greater effort in monitoring for and interventions to prevent nonadherence may be necessary to optimize stroke prevention. Increased clinician awareness of DOAC nonadherence may help identify at-risk patients. [ABSTRACT FROM AUTHOR]

Background: Endovascular aortic aneurysm repair (EVAR), left ventricular assist device (LVAD), and transcatheter aortic valve replacement (TAVR) are expensive cardiovascular technologies with potential to benefit large numbers of patients. There are few population-based studies comparing utilization between countries. Our objective was to compare patient characteristics and utilization patterns of EVAR, LVAD, and TAVR in Ontario, Canada, and New York State, United States.Methods and Results: We performed a retrospective cohort study using administrative data to identify all adults who received EVAR, LVAD, or TAVR in Ontario and New York between 2012 and 2015. We compared socio-demographics of EVAR, LVAD, and TAVR recipients in Ontario and New York. We compared standardized utilization rates between jurisdictions for each procedure. We identified 3295 EVAR recipients from Ontario and 6236 from New York (mean age 74.6 versus 74.5 years; P=0.61): 136 LVAD recipients from Ontario and 686 from New York (age, 57.4 versus 57.7 years; P=0.80): 1708 TAVR recipients from Ontario and 4838 from New York (age, 83.1 versus 83.1; P=1.0). A significantly smaller percentage of EVAR and TAVR recipients in Ontario were female compared to New York (EVAR, 15.8% versus 22.1% female; P<0.001; TAVR, 45.9% versus 51.8%; P<0.001), but for LVAD the percentage female was similar (21.3% versus 20.8%; P=0.99). Utilization was significantly higher in New York for all procedures: EVAR (12.8 procedures per-100 000 adults per-year in Ontario, 20.2 in New York; P<0.001); LVAD (0.3 in Ontario versus 1.3 in New York; P<0.001); and TAVR (6.6 in Ontario, 14.3 in New York; P<0.001). Higher utilization of EVAR and TAVR in New York relative to Ontario increased substantially with increasing age.Conclusions: We observed significantly higher utilization of EVAR, LVAD, and TAVR in New York compared to Ontario. Our results highlight important differences in how 2 different countries are using advanced cardiovascular therapies. [ABSTRACT FROM AUTHOR]

Background: Controversy exists about how best to organize systems of care for patients with out-of-hospital cardiac arrest (OHCA), as little evidence exists to guide policy-makers. In Canada, teaching hospitals are mainly cardiac referral centers that are potentially well suited towards treating patients with OHCA. Our objective was to determine whether patients with OHCA are more likely to survive if they present to teaching hospitals.Methods and Results: We conducted a retrospective observational cohort study by linking several population-based administrative databases in Ontario, Canada. All patients >20 years old who arrived alive to hospital after OHCA between April 1, 2007, and March 31, 2014, were eligible for inclusion. Patients with ST-segment-elevation myocardial infarction were excluded. The primary outcome was survival at 30 days. To determine the association between teaching status and 30-day survival, logistic regression models were used to adjust for baseline differences in patient characteristics. Prespecified analysis was performed stratified by age: ≤65, 66 to 80, and >80 years old. A total of 25 346 patients were included: 5413 at teaching and 19 933 at nonteaching hospitals. Survival at 30 days was 13.9% in teaching and 11.0% (P<0.001) in nonteaching hospitals. Hospital teaching status was associated with a significantly higher adjusted odds of 30-day survival (odds ratio, 1.38 [95% CI, 1.14-1.67]). This improvement in survival was observed in younger patients (≤65 years: odds ratio, 1.41 [95% CI, 1.14-1.74]; 66 to 80 years: odds ratio,1.37 [95% CI, 1.13-1.67]), but there was no significant difference in the elderly (>80 years: odds ratio, 1.07 [95% CI, 0.79-1.44]).Conclusions: Patients with OHCA treated at teaching hospitals were more likely to survive to 30 days. These findings support current recommendations suggesting that treatment of these patients should be provided at specialized hospitals. [ABSTRACT FROM AUTHOR]

Background: Variable selection is an important issue when developing prognostic models. Missing data occur frequently in clinical research. Multiple imputation is increasingly used to address the presence of missing data in clinical research. The effect of different variable selection strategies with multiply imputed data on the external performance of derived prognostic models has not been well examined.Methods and Results: We used backward variable selection with 9 different ways to handle multiply imputed data in a derivation sample to develop logistic regression models for predicting death within 1 year of hospitalization with an acute myocardial infarction. We assessed the prognostic accuracy of each derived model in a temporally distinct validation sample. The derivation and validation samples consisted of 11 524 patients hospitalized between 1999 and 2001 and 7889 patients hospitalized between 2004 and 2005, respectively. We considered 41 candidate predictor variables. Missing data occurred frequently, with only 13% of patients in the derivation sample and 31% of patients in the validation sample having complete data. Regardless of the significance level for variable selection, the prognostic model developed using only the complete cases in the derivation sample had substantially worse performance in the validation sample than did the models for which variables were selected using the multiply imputed versions of the derivation sample. The other 8 approaches to handling multiply imputed data resulted in prognostic models with performance similar to one another.Conclusions: Ignoring missing data and using only subjects with complete data can result in the derivation of prognostic models with poor performance. Multiple imputation should be used to account for missing data when developing prognostic models. [ABSTRACT FROM AUTHOR]

Background: The relationship between ordering frequency of rarely appropriate transthoracic echocardiograms on healthcare utilization and patient outcomes in coronary artery disease (CAD) is not known. Our objective was to investigate practice patterns of cardiologists who order a high frequency of low-value transthoracic echocardiograms in patients with CAD and whether practice behavior influences patient outcomes.Methods and Results: A retrospective cohort of outpatient CAD patients was accrued by identifying patients with at least 1 visit to 1 of 35 Ontario-based cardiologists in the EchoWISELY randomized clinical trial (Will Inappropriate Scenarios for Echocardiography Lessen Significantly) control group. The main outcomes of interest were patient-level receipt of diagnostic tests, physician visits, medication prescriptions, and clinical outcomes at 1 year. Our cohort consisted of 3966 patients with CAD (mean [SD] age, 67.8 [12.0] years; 72% men), with an outpatient visit to 1 of 35 eligible cardiologists, stratified into 3 ordering tertiles. Patients of cardiologists in the top ordering tertile of rarely appropriate transthoracic echocardiograms had significantly lower odds of receiving the following services at 1 year compared with patients in the low ordering group: cholesterol assessment (odds ratio [OR], 0.77 [95% CI, 0.65-0.91]); hemoglobin A1c assessment (OR, 0.79 [95% CI, 0.66-0.94]); β-blocker prescription (OR, 0.70 [95% CI, 0.55-0.90]); and aldosterone receptor antagonist prescription (OR, 0.46 [95% CI, 0.22-0.98]). Patients of high ordering cardiologists had greater odds of all-cause mortality at 1 year (OR, 1.54 [95% CI, 1.04-2.28]), although all other outcomes were similar.Conclusions: Patients with CAD seen by cardiologist who ordered a high rate of rarely appropriate transthoracic echocardiograms were less likely to receive potentially high-value screening tests and evidence-based medications than low ordering cardiologists.Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02038101. [ABSTRACT FROM AUTHOR]

Background: Public reporting of hospital-level outcomes is increasingly common as a means to target quality improvement strategies to ensure the delivery of optimal care. Despite the rapid dissemination of transcatheter aortic valve replacement (TAVR), there is a paucity of reliable case-mix adjustment models for hospital profiling in TAVR. Our objective was to develop and evaluate different models for calculating risk-standardized all-cause mortality rates (RSMRs) post-TAVR.Methods and Results: In this population-based study in Ontario, Canada, we identified all patients who underwent a TAVR procedure between April 1, 2012, and March 31, 2016. For each hospital, we calculated 30-day and 1-year RSMR, using 2-level hierarchical logistic regression models that accounted for patient-specific demographic and clinical characteristics, as well as the clustering of patients within the same hospital using a hospital-specific random effects. We classified each hospital into one of 3 groups: performing worse than expected, better than expected, or performing as expected, based on whether the 95% CI of the RSMR was above, below, or included the provincial average mortality rate, respectively. Our cohort consisted of 2129 TAVR procedures performed at 10 hospitals. The observed mortality was 7.0% at 30 days and 16.4% at 1 year, with a range of 4% to 10% and 8% to 22%, respectively, across hospitals. We developed case-mix adjustment models using 28 clinically relevant variables. Using 30-day and 1-year RSMR to profile each hospital, we found that all hospitals performed as expected, with 95% CI that included the provincial average.Conclusions: We found no significant interhospital variation in RSMR among hospitals, suggesting that quality improvement efforts should be directed at aspects other than the variation in observed mortality. [ABSTRACT FROM AUTHOR]

Background: Chest pain is one of the most common reasons for emergency department (ED) visits in developed countries. Whether higher volume EDs have better outcomes, specifically for patients with chest pain, is unknown and pertinent.Methods and Results: We conducted a study using population-based data on 498 291 patients ≥40 years old, presenting to ED in Ontario, Canada from 2008 to 2014, with chest pain and were discharged after assessment. We evaluated processes of care after discharge from ED. 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 outcome. We also determined if there was a volume threshold above which an increased ED volume was not associated with a lower adverse outcome. The mean age of our 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 relative decrease in the odds of the composite outcome at 30 days of <1%.Conclusions: Evaluations of chest pain in EDs with higher chest pain volume had lower rates of death or hospitalizations for acute coronary syndrome. There was a volume threshold above which an increase in volume was no longer associated with reduced outcomes. [ABSTRACT FROM AUTHOR]