Utilisation of coronary angiography after acute myocardial infarction in Ontario over time: have referral patterns changed?

Association of Neighborhood-Level Marginalization With Health Care Use and Clinical Outcomes Following Hospital Discharge in Patients Who Underwent Coronary Catheterization for Acute Myocardial Infarction in a Single-Payer Health Care System

BACKGROUND

Canadian data suggest that patients of lower socioeconomic status with acute myocardial infarction receive less beneficial therapy and have worse clinical outcomes, raising questions regarding care disparities even in universal health care systems. We assessed the contemporary association of marginalization with clinical outcomes and health services use.

METHODS

Using clinical and administrative databases in Ontario, Canada, we conducted a population-based study of patients aged ≥65 years hospitalized for their first acute myocardial infarction between April 1, 2010 and March 1, 2019. Patients receiving cardiac catheterization and surviving 7 days postdischarge were included. Our primary exposure was neighborhood-level marginalization, a multidimensional socioeconomic status metric. Neighborhoods were categorized by quintile from Q1 (least marginalized) to Q5 (most marginalized). Our primary outcome was all-cause mortality. A proportional hazards regression model with a robust variance estimator was used to quantify the association of marginalization with outcomes, adjusting for risk factors, comorbidities, disease severity, and regional cardiologist supply.

RESULTS

Among 53 841 patients (median age, 75 years; 39.1% female) from 20 640 neighborhoods, crude 1- and 3-year mortality rates were 7.7% and 17.2%, respectively. Patients in Q5 had no significant difference in 1-year mortality (hazard ratio [HR], 1.08 [95% CI, 0.95-1.22]), but greater mortality over 3 years (HR, 1.13 [95% CI, 1.03-1.22]) compared with Q1. Over 1 year, we observed differences between Q1 and Q5 in visits to primary care physicians (Q1, 96.7%; Q5, 93.7%) and cardiologists (Q1, 82.6%; Q5, 72.6%), as well as diagnostic testing. There were no differences in secondary prevention medications dispensed or medication adherence at 1 year.

CONCLUSIONS

In older patients with acute myocardial infarction who survived to hospital discharge, those residing in the most marginalized neighborhoods had a greater long-term risk of mortality, less specialist care, and fewer diagnostic tests. Yet, there were no differences across socioeconomic status in prescription medication use and adherence.

Socioeconomic Status, Mortality, and Access to Cardiac Services After Acute Myocardial Infarction in Canada: A Systematic Review and Meta-analysis

Background

Low socioeconomic status (SES) is an important prognosticator for those with acute myocardial infarction (AMI), having previously been described to be associated with increased short-term mortality. Whether this effect persists over time, and whether access to cardiac interventions is equitable within Canada’s universal health care system, remains unknown.

Methods

We conducted a systematic review to determine the associations of SES with mortality and access to a spectrum of interventions including cardiac catheterization, revascularization, and cardiac rehabilitation. Electronic databases (EMBASE and MEDLINE) were searched in March 2019 and December 2019. Original studies from Canada examining associations between SES and any of the above outcomes in AMI patients were included. Meta-analyses were conducted using random effects models.

Results

Nineteen studies were included, 11 of which could be meta-analyzed. Low SES was associated with a 48% and 34% increase in short-term and intermediate-term mortality, respectively. There was a trend toward increased long-term mortality more than 1-year post-event (pooled odds ratio [OR] 1.34 [95% confidence interval {CI} 0.95-1.88]). Low SES was also associated with lower rates of cardiac catheterization (pooled OR 0.80 [95% CI 0.65-0.99]) and revascularization (pooled OR 0.76 [95% CI 0.63-0.90]) post-AMI. Studies on cardiac rehabilitation showed reduced access and participation in low-SES groups.

Conclusions

Low SES is associated with not only increased mortality post-AMI, but also reduced access to cardiac interventions that have demonstrated benefits for mortality and morbidity. Interventions that improve access to catheterization, revascularization, and cardiac rehabilitation for low-SES populations are needed if true equitable care in Canada is desired.

Socioeconomic inequalities in access to treatment for coronary heart disease: A systematic review

Strong socioeconomic inequalities exist in cardiovascular mortality and morbidity. The current review aims to synthesize the current evidence on the association between socioeconomic status (SES) and access to treatment of coronary heart disease (CHD). We examined quantitative studies analyzing the relationship between SES and access to CHD treatment that were published between 1996 and 2015. Our data sources included Medline and Web of Science. Our search yielded a total of 2066 records, 57 of which met our inclusion criteria. Low SES was found to be associated with low access to coronary procedures and secondary prevention. Access to coronary procedures, especially coronary angiography, was mainly related to SES to the disadvantage of patients with low SES. However, access to drug treatment and cardiac rehabilitation was only associated with SES in about half of the studies. The association between SES and access to treatment for CHD was stronger when SES was measured based on individual-level compared to area level, and stronger for individuals living in countries without universal health coverage. Socioeconomic inequalities exist in access to CHD treatment, and universal health coverage shows only a minor effect on this relationship. Inequalities diminish along the treatment pathway for CHD from diagnostic procedures to secondary prevention. We therefore conclude that CHD might be underdiagnosed in patients with low SES. Our results indicate that there is an urgent need to improve access to CHD treatment, especially by increasing the supply of diagnostic angiographies, to reduce inequalities across different healthcare systems.

Age difference explains gender difference in cardiac intervention rates after acute myocardial infarction

Many investigators have reported higher rates of cardiac procedures for males than females after acute myocardial infarction (AMI), suggesting that men are treated more aggressively than women. However, others have reported no significant differences after controlling for age, resulting in uncertainty about the existence of a true gender bias in cardiac care. In this study, a population-based cohort approach was used to calculate age-specific procedure rates by sex from administrative data. Chi-square tests and generalized linear modelling were used to assess gender differences and interactions. For all four procedures studied, rates were significantly higher for males than females (p<0.01). However, age-specific rates revealed few significant differences by gender and a sharp decrease in intervention rates with age for both males and females. Generalized linear modelling confirmed that patient age was a significant predictor of intervention rates, whereas sex was not. The significant gender difference in overall rates was completely confounded by the older age profile of female AMI patients compared to their male counterparts.

Impact of clinical urgency, physician supply and procedural capacity on regional variations in wait times for coronary angiography

Background

Despite universal health care, there continues to be regional access disparities to coronary angiography in Canada. Our objective was to evaluate the extent to which demand-side factors such as clinical urgency/need, and supply-side factors, as reflected by differences in physician and procedural supply account for these inequalities.

Methods

Our cohort consisted of 74,254 consecutive patients referred for coronary angiography in Ontario, Canada between April 1^st 2005 and March 31^st 2006, divided into three urgency strata based on a clinical urgency scale. Cox-proportional hazard models were developed, adjusting for age, gender, socioeconomic status (SES), region, and urgency score, with greater hazard ratios (HR) indicating shorter wait times. To evaluate mediators of any residual wait-time differences, we examined the influence of the regional supply of cath lab facilities, invasive cardiologists and general practitioners (GP).

Results

We found that the urgency score was a significant predictor of wait time in all three strata (urgent patients: HR 1.61 for each unit increase in patient urgency (95% Confidence interval (CI) 1.55-1.67); semi-urgent patients: HR 1.55 (95% CI 1.44-1.68); elective patients: HR 1.13 (95% CI 1.08-1.18)). After accounting for clinical need/urgency, regional wait time differences persisted; these were most consistently associated with variation in cath lab supply. The impact of invasive cardiologist supply was restricted to urgent patients while that of GP supply was confined to semi-urgent and elective patients.

Conclusion

We found that there remained significant regional disparities in access to coronary angiography after accounting for clinical need. These disparities are partially explained by variations in supply of both procedural capacity and physician services, most notably in elective and semi-urgent patients.

The relationship between physician supply, cardiovascular health service use and cardiac disease burden in Ontario: supply-need mismatch

BACKGROUND

While health service use appears to be positively correlated with resource availability, no study has explored the interactions among health service supply, cardiovascular disease burden and health service use. The objective of the present study was to examine the relationship among cardiovascular evaluation and management intensity, physician supply and cardiovascular disease burden in the Canadian population.

METHODS

The present cross-sectional, population-based study consisted of adult residents in Ontario in 2001. Cardiac evaluation and management intensity, the main outcome measure, was measured at the individual level, and consisted of receiving one or more of the following services: noninvasive cardiac testing, coronary angiography and statin use (the latter among individuals 65 years of age and older). Mortality was the secondary outcome measure. Cardiovascular disease burden, and cardiologist and primary care physician supply were measured at the regional (ie, county) level. Analyses were adjusted for age and sex using Poisson regression, accounting for regional clustering.

RESULTS

Regional per capita cardiologist supply varied more than twofold across regions, but was inversely related to the regional cardiovascular disease burden (r=-0.34, P=0.01). Primary care physician supply was relatively evenly distributed across regions. Residents in areas with more cardiologists were more likely to receive some form of cardiac intervention (RR=1.074, 95% CI 1.066 to 1.082 per additional cardiologist per 100,000). Those in areas with more primary care physicians were also more likely to receive noninvasive cardiac testing (RR=1.056, 95% CI 1.051 to 1.061 per six additional primary care physicians per 100,000). However, the intensity of provision of cardiac health services was unrelated to regional cardiovascular disease burden and was not associated with improved survival.

CONCLUSIONS

The mismatch between physician supply and cardiac disease burden may explain why cardiovascular health service use is neither concordant with the cardiovascular disease burden nor associated with mortality in the population. These results underscore the importance of physician service maldistribution and supply-sensitive care on the appropriateness of cardiac health service use.

The influence of a "culture of referral" on access to care in rural settings after myocardial infarction

Access to care is an issue for rural people who require tertiary care following a myocardial infarction (MI). Access to specialized cardiac health services is contingent upon referral to tertiary care in urban centers. Using a critical ethnographic approach, rural women, their nurses and physicians were interviewed to explore how rurality affected women's referral and access to care following a MI. Findings reflect that a previously undocumented culture of referral that was shaped by human factors influenced access to care. The culture of referral reflected an urban-centric approach to the provision of cardiovascular services and a medical hierarchy within the referral system. The findings extend conceptual understandings of access to health care in relation to rural populations.

ICD-10 adaptations of the Ontario acute myocardial infarction mortality prediction rules performed as well as the original versions

OBJECTIVE

To derive and validate an International Classification of Diseases-10 (ICD-10) version of the Ontario Acute Myocardial Infarction (AMI) mortality prediction rules, used to adjust for case-mix differences in studies of AMI patients using administrative data.

STUDY DESIGN AND SETTING

We linked the records of all Ontario patients admitted with AMI (2002-2004) with mortality data. The original ICD-9 codes were mapped to ICD-10-CA (Canada) codes using both a translation produced by coding experts and a manual search of codes; the final codes were determined by consensus. Comorbidity prevalence and mortality rates were calculated. Multivariable logistic regression models were used to predict 30-day and 1-year mortality and the C-statistic was used to evaluate the discrimination of the models.

RESULTS

We identified 37,271 AMI patients. The most common comorbidities were heart failure and dysrhythmias; 30-day and 1-year mortality rates were 12.3% and 21.8%, respectively; and mortality rates were highest among patients with shock, cancer, and acute renal failure. The C-statistics were 0.77 and 0.80, compared with 0.78 and 0.79 in the ICD-9 version, for 30-day and 1-year mortality, respectively.

CONCLUSION

An ICD-10 version of the AMI mortality prediction rules predicted 30-day and 1-year mortality as well as the original ICD-9 version.

Effect of the new diagnostic criteria for ST-elevation and non-ST-elevation acute myocardial infarction on 4-year hospitalization: an analysis of hospital discharge records in the Veneto Region

OBJECTIVE

To assess the burden of hospitalization for acute coronary syndrome (ACS) and the impact of the new diagnostic criteria for acute myocardial infarction on epidemiology of ACSs.

METHODS

We analysed the hospital discharge record archives of the Veneto Region in the period 2000-2003, including admissions of regional residents outside the study area. We defined a list of ICD-9-CM codes for the identification of different types of ACS. We examined trends in standardized hospitalization rates as well as patient characteristics (age, sex) and pattern of care (setting, invasive revascularization, length of hospital stay, in-hospital mortality).

RESULTS

The hospitalization rate for non-ST-elevation myocardial infarction increased by about 70%, with a parallel decrease in hospitalizations for unstable angina, whereas the hospitalization rate for ST-elevation myocardial infarction remained unchanged. These trends are likely influenced by the new diagnostic criteria for acute myocardial infarction. At the end of the study period, although the main patient characteristics did not vary substantially, the pattern of care turned out to be more aggressive.

CONCLUSIONS

Despite some limitations, our results indicate that the new diagnostic criteria for acute myocardial infarction have a major impact on epidemiological evaluation. These data may be relevant when comparing epidemiological data of different periods and planning healthcare policies. Further studies are needed in order to evaluate the accuracy of ICD-9-CM codes in the diagnosis of ACSs.

Proliferation of Cardiac Technology in Canada

Background— Critics remain skeptical about the long-term sustainability of Medicare in Canada because of the proliferation of health technology and escalating expenditures. The objective of this study was to examine the temporal trends in the utilization and costs of cardiovascular technologies for the evaluation and/or management of patients with ischemic heart disease in Canada.

Methods and Results— This repeated cross-sectional population-based study of Ontario residents examined the temporal trends in the utilization and costs associated with echocardiography, stress (imaging and nonimaging) testing, coronary angiography, percutaneous coronary intervention (PCI), and bypass surgery between 1992 and 2001. Annual costs increased by nearly 2-fold over the 10-year study period and cumulatively accounted for more than $2.8 billion (Canadian) in expenditures. The proliferation in use of cardiac testing/interventions over time outstripped both demographic shifts and changes in the prevalence of coronary artery disease. Annual increases were widespread for all procedures ( P <0.001) and ranged from 2% per year for nonimaging stress tests to 12% per year for PCI, after adjustment for age and sex. Generally, utilization rates were higher among the elderly, males, and those of low socioeconomic status. With few exceptions, annual increases in the utilization rates of cardiac tests and procedures were disproportionately higher among the elderly and women, but they were similar across socioeconomic subgroups. Increases in utilization appeared to reflect referrals toward higher-risk populations.

Conclusions— Although definitive conclusions about the appropriateness of temporal patterns cannot be ascertained, the proliferation of cardiac testing challenges the sustainability of Medicare in Canada, especially given uncertainty as to whether the accompanying incremental rise in total expenditures translates into significant outcome benefits in the population.

Primary Angioplasty for the Treatment of Acute ST-Segment Elevated Myocardial Infarction: An Evidence-Based Analysis

One of the longest running debates in cardiology is about the best reperfusion therapy for patients with evolving acute myocardial infarction (MI). Percutaneous transluminal coronary angioplasty (ANGIOPLASTY) is a surgical treatment to reopen a blocked coronary artery to restore blood flow. It is a type of percutaneous (through-the-skin) coronary intervention (PCI) also known as balloon angioplasty. When performed on patients with acute myocardial infarction, it is called primary angioplasty. Primary angioplasty is an alternative to thrombolysis, clot-dissolving drug therapy, for patients with acute MI associated with ST-segment elevation (STEMI), a change recorded with an electrocardiogram (ECG) during chest pain.This review of the clinical benefits and policy implications of primary angioplasty was requested by the Ontario Health Technology Advisory Committee and prompted by the recent publication of a randomized controlled trial (RCT) in the New England Journal of Medicine (1) that compared referred primary angioplasty with on-site thrombolysis. The Medical Advisory Secretariat reviewed the literature comparing primary angioplasty with thrombolysis and other therapies (pre-hospital thrombolysis and facilitated angioplasty, the latter approach consisting of thrombolysis followed by primary angioplasty irrespective of response to thrombolysis) for acute STEMI.There have been many RCTs and meta-analyses of these RCTs comparing primary angioplasty with thrombolysis and these were the subject of this analysis. Results showed a statistically significant reduction in mortality, reinfarction, and stroke for patients receiving primary angioplasty. Although the individual trials did not show significant improvements in mortality alone, they did show it for the outcomes of nonfatal reinfarction and stroke, and for an end point combining mortality, reinfarction, and stroke. However, researchers have raised concerns about these studies.A main concern with the large RCTs is that they lack consistency in methods. Furthermore, there is some question as to their generalizability to practice in Ontario. Across the RCTs, there were differences in the type of thrombolytic drug, the use of stenting versus balloon-only angioplasty, and the use of the newer antiplatelet glycoprotein IIb/IIIa. The largest trial did not offer routine follow-up angioplasty for patients receiving thrombolysis, which is the practice in Ontario, and the meta-analysis included trials with streptokinase, an agent seldom used in hospitals in Ontario. Thus, the true magnitude of mortality benefit can only be surmised from head-to-head comparisons of current standard therapies for primary angioplasty and for thrombolysis.By taking a more restrictive sample of the available studies, the Medical Advisory Secretariat conducted a review that was more consistent with patterns of practice in Ontario and selected trials that used accelerated alteplase as the thrombolytic agent.Results from this meta-analysis suggest that the rates for primary angioplasty are significantly better for mortality, reinfarction, and stroke, in the short term (30 days), and for mortality, reinfarction, and the combined end point at 6 months. When primary angioplasty was compared with in-hospital thrombolysis, results showed a significant reduction in adverse event rates associated with primary angioplasty. However, 1 large RCT of pre-hospital thrombolysis (i.e., thrombolysis given by paramedics before arriving at the hospital) compared with primary angioplasty documented that pre-hospital thrombolysis is an equivalent intervention to primary thrombolysis in terms of survival. Furthermore, a meta-analysis of studies that compared pre-hospital thrombolysis with in-hospital thrombolysis showed a reduction in all hospital mortality rates in favour of pre-hospital thrombolysis, supporting the findings of the pre-hospital thrombolysis study. (2)Clinical trials to date have reported that hospital stay is often reduced for patients who receive primary angioplasty compared with thrombolysis. Using a cost-analysis performed alongside the only study from Ontario, the Medical Advisory Secretariat concluded that there might be savings associated with primary angioplasty. These savings may partly offset the investment the provincial government would have to make to increase access to this technology. These savings should also be shown outside of a clinical trial protocol if the overall efficiencies of primary angioplasty are to be verified.Based on this health technology policy analysis, the Medical Advisory Secretariat concludes that primary angioplasty has advantages with respect to mortality and combined end points compared with in-hospital thrombolysis (Level 1 evidence). However, pre-hospital thrombolysis improves survival compared with in-hospital thrombolysis (Level 1 evidence) and is equivalent to primary angioplasty (Level 1 evidence).Results from the literature review raise concerns about the loss of therapeutic advantage due to treatment delays, time lapse from symptom onset to revascularization, time-of-day variations, the hospital volume of procedures, and the ability of hospitals to achieve in practice what RCTs have shown.Furthermore, questions relevant to applying primary angioplasty widely, involve the diagnosis by paramedics, ambulance diversion protocols, paramedic training, and inter-hospital transfer protocols. These logistical considerations need to be addressed to realise the potential to improve patient outcomes. In its analysis, the Medical Advisory Secretariat concludes that it is unrealistic to reorganise the emergency medical services across Ontario to fully implement a primary angioplasty program.Finally, it is important to evaluate the potential of this technology in the context of Ontario's health system. This includes urban and rural considerations, the ability to expand access to primary angioplasty and to minimize symptom-to-assessment time through a diverse strategy including public awareness. Therefore, a measured, evaluative approach to adopting this technology is warranted.Furthermore, the alternative approach to pre-hospital or early thrombolysis, especially within 120 minutes from onset of symptoms, should be considered when developing the approach to improving outcomes for acute MI. This could include efforts to decrease the symptom-to-thrombolysis time through strategies such as a concerted public education program to expedite presentation to emergency rooms after onset of symptoms, a pre-hospital ECG and thrombolysis checklist in ambulances to reduce door-to-needle time on arrival at emergency rooms, and, especially in remote areas, access to pre-hospital thrombolysis.The Medical Advisory Secretariat therefore recommends that this analysis of primary angioplasty be viewed in the overall context of all interventions for the management of acute MI and, in particular, of improving access to primary angioplasty and maximising the use of early thrombolysis.Outcomes for patients with acute MI can be improved if efforts are made to optimise the interval from symptom onset to thrombolysis or angioplasty. This will require concerted efforts, including public awareness through education to reduce the symptom-to-emergency room time, and maximising efficiencies in door-to-intervention times for primary angioplasty and for early thrombolysis.Primary angioplasty and early thrombolysis cannot be considered in isolation from one another. For example, patients who have persistent STEMI 90 minutes after receiving thrombolysis should be considered for angioplasty ("rescue angioplasty"). Furthermore, for patients with acute MI who are in cardiac shock, primary angioplasty is considered the preferred intervention. The concomitant use of primary angioplasty and thrombolysis ("facilitated angioplasty") is considered experimental and has no place in routine management of acute MI at this time. In remote parts of the province, consideration should be given to introducing pre-hospital thrombolysis as the preferred intervention through upgrading a select number of paramedics to advanced care status.