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1.  Temporal Trends in the Utilization of Echocardiography in Ontario, 2001-2009 
JACC. Cardiovascular imaging  2013;6(4):515-522.
The purpose of this study was to examine utilization and growth in echocardiography among the general population of Ontario between 2001 and 2009. The age- and sex-adjusted rates of echocardiography grew from 39.1 per 1,000 persons in 2001 to 59.9 per 1,000 persons in 2009, for an annual rate of increase of 5.5%. Repeat echocardiograms increased at a rate of 10.6% per year and accounted for 25.3% of all procedures in 2009 as compared to 18.5% in 2002. While significant increases in echocardiography utilization were observed, opportunities may exist to improve the clinical utility of the echocardiograms performed in Ontario.
PMCID: PMC3915739  PMID: 23579013
echocardiography; resource utilization; cardiovascular imaging
2.  The CANHEART health index: a tool for monitoring the cardiovascular health of the Canadian population 
To comprehensively examine the cardiovascular health of Canadians, we developed the Cardiovascular Health in Ambulatory Care Research Team (CANHEART) health index. We analyzed trends in health behaviours and factors to monitor the cardiovascular health of the Canadian population.
We used data from the Canadian Community Health Survey (2003–2011 [excluding 2005]; response rates 70%–81%) to examine trends in the prevalence of 6 cardiovascular health factors and behaviours (smoking, physical activity, fruit and vegetable consumption, overweight/obesity, diabetes and hypertension) among Canadian adults aged 20 or older. We defined ideal criteria for each of the 6 health metrics. The number of ideal metrics was summed to create the CANHEART health index; values range from 0 (worst) to 6 (best or ideal). A separate CANHEART index was developed for youth age 12–19 years; this index included 4 health factors and behaviours (smoking, physical activity, fruit and vegetable consumption and overweight/obesity). We determined the prevalence of ideal cardiovascular health and the mean CANHEART health index score, stratified by age, sex and province.
During the study period, physical activity and fruit and vegetable consumption increased and smoking decreased among Canadian adults. The prevalence of overweight/obesity, hypertension and diabetes increased. In 2009–2010, 9.4% of Canadian adults were in ideal cardiovascular health, 53.3% were in intermediate health (4–5 healthy factors or behaviours), and 37.3% were in poor cardiovascular health (0–3 healthy factors or behaviours). Twice as many women as men were in ideal cardiovascular health (12.8% vs. 6.1%). Among youth, the prevalence of smoking decreased and the prevalence of overweight/obesity increased. In 2009–2010, 16.6% of Canadian youth were in ideal cardiovascular health, 33.7% were in intermediate health (3 healthy factors or behaviours), and 49.7% were in poor cardiovascular health (0–2 healthy factors or behaviours).
Fewer than 1 in 10 Canadian adults and 1 in 5 Canadian youth were in ideal cardiovascular health from 2003 to 2011. Intensive health promotion activities are needed to meet the Heart and Stroke Foundation of Canada’s goal of improving the cardiovascular health of Canadians by 10% by 2020 as measured by the CANHEART health index.
PMCID: PMC3928209  PMID: 24366893
3.  Access to primary percutaneous coronary intervention for ST-segment elevation myocardial infarction in Canada: a geographic analysis 
Open Medicine  2010;4(1):e13-e21.
Primary percutaneous coronary intervention (PCI) is preferred over fibrinolysis for the treatment of ST-segment elevation myocardial infarction (STEMI). In the United States, nearly 80% of people aged 18 years and older have access to a PCI facility within 60 minutes. We conducted this study to evaluate the areas in Canada and the proportion of the population aged 40 years and older with access to a PCI facility within 60, 90 and 120 minutes.
We used geographic information systems to estimate travel times by ground transport to PCI facilities across Canada. Time to dispatch, time to patient and time at the scene were considered in the overall access times. Using 2006 Canadian census data, we extracted the number of adults aged 40 years and older who lived in areas with access to a PCI facility within 60, 90 and 120 minutes. We also examined the effect on these estimates of the hypothetical addition of new PCI facilities in underserved areas.
Only a small proportion of the country’s geographic area was within 60 minutes of a PCI facility. Despite this, 63.9% of Canadians aged 40 and older had such access. This proportion varied widely across provinces, from a low of 15.8% in New Brunswick to a high of 72.6% in Ontario. The hypothetical addition of a single facility to each of 4 selected provinces could increase the proportion by 3.2% to 4.3%, depending on the province. About 470 000 adults would gain access in such a scenario of new facilities.
We found that nearly two-thirds of Canada’s population aged 40 years and older had timely access to PCI facilities. The proportion varied widely across the country. Such information can inform the development of regionalized STEMI care models.
PMCID: PMC3116676  PMID: 21686287
4.  The Average Lifespan of Patients Discharged from Hospital with Heart Failure 
Journal of General Internal Medicine  2012;27(9):1171-1179.
There are no life-tables quantifying the average life-spans of post-hospitalized heart failure populations across various strata of risk.
To quantify the life-expectancies (i.e., average life-spans) of heart failure patients at the time of hospital discharge according to age, gender, predictive 30-day mortality heart failure risk index, and comorbidity burden.
Population-based retrospective cohort study.
Ontario, Canada.
7,865 heart failure patients discharged from Ontario hospitals between 1999 and 2000.
Data were obtained from the Enhanced Feedback for Effective Cardiac Treatment EFFECT provincial quality improvement initiative. All patients were linked to administrative data, and tracked longitudinally until March 31, 2010. Detailed clinical variables were obtained from medical chart abstraction, and death data were obtained from vital statistics. Average life-spans were calculated using Cox Proportion Hazards models in conjunction with the Declining Exponential Approximation of Life Expectancy (D.E.A.L.E) method to extrapolate life-expectancy, adjusting for age, gender, predicted 30-day mortality, left ventricular function and comorbidity, and was reported according to key prognostic risk-strata.
The average life-span of the cohort was 5.5 years (STD +/− 10.0) ranging from 19.5 years for low-risk women of less than 50 years old to 2.9 years for high-risk octogenarian males. Average life-spans were lower by 0.13 years among patients with impaired as compared with preserved left ventricular function, and by approximately one year among patients with three or more as compared with no concomitant comorbidities. In total, 17.4 % and 27 % of patients had died within 6 months and 1 year respectively, despite having predicted life-spans exceeding one-year.
Data regarding changes in patient clinical status over time were unavailable.
The development of risk-adjusted life-tables for heart failure populations is feasible and mirrored those with advanced malignant diseases. Average life span varied widely across clinical risk strata, and may be less accurate among those at or near their end of life.
PMCID: PMC3515002  PMID: 22549300
life-expectancy; heart failure; risk; survival; comorbidity
6.  Effect of a provincial system of stroke care delivery on stroke care and outcomes 
Systems of stroke care delivery have been promoted as a means of improving the quality of stroke care, but little is known about their effectiveness. We assessed the effect of the Ontario Stroke System, a province-wide strategy of regionalized stroke care delivery, on stroke care and outcomes in Ontario, Canada.
We used population-based provincial administrative databases to identify all emergency department visits and hospital admissions for acute stroke and transient ischemic attack from Jan. 1, 2001, to Dec. 31, 2010. Using piecewise regression analyses, we assessed the effect of the full implementation of the Ontario Stroke System in 2005 on the proportion of patients who received care at stroke centres, and on rates of discharge to long-term care facilities and 30-day mortality after stroke.
We included 243 287 visits by patients with acute stroke or transient ischemic attack. The full implementation of the Ontario Stroke System in 2005 was associated with an increase in rates of care at stroke centres (before implementation: 40.0%; after implementation: 46.5%), decreased rates of discharge to long-term care facilities (before implementation: 16.9%; after implementation: 14.8%) and decreased 30-day mortality for hemorrhagic (before implementation: 38.3%; after implementation: 34.4%) and ischemic stroke (before implementation: 16.3%; after implementation: 15.7%). The system’s implementation was also associated with marked increases in the proportion of patients who received neuroimaging, thrombolytic therapy, care in a stroke unit and antithrombotic therapy.
The implementation of an organized system of stroke care delivery was associated with improved processes of care and outcomes after stroke.
PMCID: PMC3708028  PMID: 23713072
7.  Discriminating clinical features of heart failure with preserved vs. reduced ejection fraction in the community 
European Heart Journal  2012;33(14):1734-1741.
Heart failure (HF) is a major public health burden worldwide. Of patients presenting with HF, 30–55% have a preserved ejection fraction (HFPEF) rather than a reduced ejection fraction (HFREF). Our objective was to examine discriminating clinical features in new-onset HFPEF vs. HFREF.
Methods and results
Of 712 participants in the Framingham Heart Study (FHS) hospitalized for new-onset HF between 1981 and 2008 (median age 81 years, 53% female), 46% had HFPEF (EF >45%) and 54% had HFREF (EF ≤45%). In multivariable logistic regression, coronary heart disease (CHD), higher heart rate, higher potassium, left bundle branch block, and ischaemic electrocardiographic changes increased the odds of HFREF; female sex and atrial fibrillation increased the odds of HFPEF. In aggregate, these clinical features predicted HF subtype with good discrimination (c-statistic 0.78). Predictors were examined in the Enhanced Feedback for Effective Cardiac Treatment (EFFECT) study. Of 4436 HF patients (median age 75 years, 47% female), 32% had HFPEF and 68% had HFREF. Distinguishing clinical features were consistent between FHS and EFFECT, with comparable discrimination in EFFECT (c-statistic 0.75). In exploratory analyses examining the traits of the intermediate EF group (EF 35–55%), CHD predisposed to a decrease in EF, whereas other clinical traits showed an overlapping spectrum between HFPEF and HFREF.
Multiple clinical characteristics at the time of initial HF presentation differed in participants with HFPEF vs. HFREF. While CHD was clearly associated with a lower EF, overlapping characteristics were observed in the middle of the left ventricular EF range spectrum.
PMCID: PMC3530391  PMID: 22507977
Heart failure; Epidemiology; Risk factors; Ejection fraction
8.  Economic analysis of Heart and Stroke Foundation of Ontario’s Hypertension Management Initiative 
Hypertension is suboptimally treated in primary care settings. We evaluated the cost-effectiveness of the Heart and Stroke Foundation of Ontario’s Hypertension Management Initiative (HMI), an interdisciplinary, evidence-informed chronic disease management model for primary care that focuses on improving blood pressure management and control by primary care providers and patients according to clinical best practice guidelines.
The perspective of our analysis was that of the Ontario Ministry of Health and Long-Term Care with a lifetime horizon and 5% annual discount rate. Using data from a prospective cohort study from the HMI, we created two matched groups: pre-HMI (standard care), and post-HMI (n = 1720). For each patient, we estimated the 10-year risk of cardiovascular disease (CVD) using the Framingham risk equation and life expectancy from life tables. Long-term health care costs incurred with physician visits, acute and chronic care hospitalizations, emergency department visits, same-day surgeries, and medication use were determined through linkage to administrative databases, using a bottom-up approach.
The HMI intervention was associated with significant reductions in systolic blood pressure (126 mmHg vs 134 mmHg with standard care; P-value < 0.001). These improvements were associated with a reduction in the 10-year risk of CVD (9.5% risk vs 10.7% in standard care; P-value < 0.001) and a statistically significant improvement in discounted life expectancy (9.536 years vs 9.516 in standard care; P-value < 0.001). The HMI cohort had a discounted mean lifetime cost of $22,884 CAD vs $22,786 CAD for standard care, with an incremental cost-effectiveness ratio of $4939 CAD per life-year gained.
We found that the HMI is a cost-effective means of providing evidence-informed, chronic disease management in primary care to patients with hypertension.
PMCID: PMC3501398  PMID: 23180969
hypertension; economic evaluation; cardiovascular disease
9.  Regression trees for predicting mortality in patients with cardiovascular disease: What improvement is achieved by using ensemble-based methods? 
In biomedical research, the logistic regression model is the most commonly used method for predicting the probability of a binary outcome. While many clinical researchers have expressed an enthusiasm for regression trees, this method may have limited accuracy for predicting health outcomes. We aimed to evaluate the improvement that is achieved by using ensemble-based methods, including bootstrap aggregation (bagging) of regression trees, random forests, and boosted regression trees. We analyzed 30-day mortality in two large cohorts of patients hospitalized with either acute myocardial infarction (N = 16,230) or congestive heart failure (N = 15,848) in two distinct eras (1999–2001 and 2004–2005). We found that both the in-sample and out-of-sample prediction of ensemble methods offered substantial improvement in predicting cardiovascular mortality compared to conventional regression trees. However, conventional logistic regression models that incorporated restricted cubic smoothing splines had even better performance. We conclude that ensemble methods from the data mining and machine learning literature increase the predictive performance of regression trees, but may not lead to clear advantages over conventional logistic regression models for predicting short-term mortality in population-based samples of subjects with cardiovascular disease.
PMCID: PMC3470596  PMID: 22777999 CAMSID: cams2404
Acute myocardial infarction; Bagging; Boosting; Data mining; Heart failure
10.  Trends in the incidence and outcomes of heart failure in Ontario, Canada: 1997 to 2007 
Heart failure is a leading cause of admission to hospital, but whether the incidence of heart failure is increasing or decreasing is uncertain. We examined temporal trends in the incidence and outcomes of heart failure in Ontario, Canada.
Using population-based administrative databases of hospital discharge abstracts and physician health insurance claims, we identified 419 551 incident cases of heart failure in Ontario between Apr. 1, 1997, and Mar. 31, 2008. All patients were classified as either inpatients or outpatients based on the patient’s location at the time of the initial diagnosis. We tracked subsequent outcomes through linked administrative databases.
The age- and sex-standardized incidence of heart failure decreased 32.7% from 454.7 per 100 000 people in 1997 to 306.1 per 100 000 people in 2007 (p < 0.001). A comparable decrease in incidence occurred in both inpatient and outpatient settings. The greatest relative decrease occurred in patients aged 85 and over. Over the study period, 1-year risk-adjusted mortality decreased from 17.7% in 1997 to 16.2% in 2007 (p = 0.02) for outpatients, with a nonsignificant decrease from 35.7% in 1997 to 33.8% in 2007 (p = 0.1) for inpatients.
The incidence of heart failure decreased substantially during the study period. Nevertheless, the prognosis for patients with heart failure remains poor and is associated with high mortality.
PMCID: PMC3470643  PMID: 22908143
11.  Deriving Ethnic-Specific BMI Cutoff Points for Assessing Diabetes Risk 
Diabetes Care  2011;34(8):1741-1748.
The definition of obesity (BMI ≥30 kg/m2), a key risk factor of diabetes, is widely used in white populations; however, its appropriateness in nonwhite populations has been questioned. We compared the incidence rates of diabetes across white, South Asian, Chinese, and black populations and identified equivalent ethnic-specific BMI cutoff values for assessing diabetes risk.
We conducted a multiethnic cohort study of 59,824 nondiabetic adults aged ≥30 years living in Ontario, Canada. Subjects were identified from Statistics Canada’s population health surveys and followed for up to 12.8 years for diabetes incidence using record linkages to multiple health administrative databases.
The median duration of follow-up was 6 years. After adjusting for age, sex, sociodemographic characteristics, and BMI, the risk of diabetes was significantly higher among South Asian (hazard ratio 3.40, P < 0.001), black (1.99, P < 0.001), and Chinese (1.87, P = 0.002) subjects than among white subjects. The median age at diagnosis was lowest among South Asian (aged 49 years) subjects, followed by Chinese (aged 55 years), black (aged 57 years), and white (aged 58 years) subjects. For the equivalent incidence rate of diabetes at a BMI of 30 kg/m2 in white subjects, the BMI cutoff value was 24 kg/m2 in South Asian, 25 kg/m2 in Chinese, and 26 kg/m2 in black subjects.
South Asian, Chinese, and black subjects developed diabetes at a higher rate, at an earlier age, and at lower ranges of BMI than their white counterparts. Our findings highlight the need for designing ethnically tailored prevention strategies and for lowering current targets for ideal body weight for nonwhite populations.
PMCID: PMC3142051  PMID: 21680722
12.  Use of Fibrates in the United States and Canada 
Jama  2011;305(12):1217-1224.
Interest in the role of fibrates has intensified with the publication of the negative ACCORD trial with fenofibrate, especially since the evidence for clinical outcomes benefit for fibrates is heavily weighted on older fibrates, gemfibrozil and clofibrate.
This study seeks to examine trends in the current use of fibrates, and for fenofibrate, to illuminate the relationship between differences in the availability of proprietary versus generic formulations and use and economic implications in the United States (US) compared with Canada.
Population-level, cohort study using IMS Health data in the United States and Canada of patients prescribed fibrates between 2002 and 2009.
Main Outcome Measure(s)
Fibrate prescribing and expenditures.
From 2002–2009, fibrate prescriptions increased 117.1% in the US, by 12,000/month to 2.1 million prescriptions/month, yet only increased by 18.1% in Canada. (p<0.001) Fenofibrate use was relatively constant in Canada, while in the US, it increased by 159.3%, comprising 47.9% of total fibrate prescriptions in 2002 and 65.2% in 2009. The annual ratio of generic:brand fenofibrate use in the US from 2002 to 2008 ranged from 0:1 to 0.09:1, while the ratio in Canada steadily increased from 2005 to 2008 from 0.51:1 to 1.89:1. In the US, crude fenofibrate expenditures rose from $33.2 million/month in 2002 to $129.6 million/month in 2009, while those in Canada declined from $5.6 million/month to $5.1 million/month. Fibrate expenditures per 100,000 population were 3-fold higher in the US compared with Canada in 2009.
During the past decade, prescriptions for fibrates, particularly, fenofibrate, increased in the United States, while prescriptions for fibrates in Canada remained stable.
PMCID: PMC3332101  PMID: 21427374
13.  Determinants of variations in coronary revascularization practices 
The ratio of percutaneous coronary interventions to coronary artery bypass graft surgeries (PCI:CABG ratio) varies considerably across hospitals. We conducted a comprehensive study to identify clinical and nonclinical factors associated with variations in the ratio across 17 cardiac centres in the province of Ontario.
In this retrospective cohort study, we selected a population-based sample of 8972 patients who underwent an index cardiac catheterization between April 2006 and March 2007 at any of 17 hospitals that perform invasive cardiac procedures in the province. We classified the hospitals into four groups by PCI:CABG ratio (low [< 2.0], low–medium [2.0–2.7], medium–high [2.8–3.2] and high [> 3.2]). We explored the relative contribution of patient, physician and hospital factors to variations in the likelihood of patients receiving PCI or CABG surgery within 90 days after the index catheterization.
The mean PCI:CABG ratio was 2.7 overall. We observed a threefold variation in the ratios across the four hospital ratio groups, from a mean of 1.6 in the lowest ratio group to a mean of 4.6 in the highest ratio group. Patients with single-vessel disease usually received PCI (88.4%–99.0%) and those with left main artery disease usually underwent CABG (80.8%–94.2%), regardless of the hospital’s procedure ratio. Variation in the management of patients with non-emergent multivessel disease accounted for most of the variation in the ratios across hospitals. The mode of revascularization largely reflected the recommendation of the physician performing the diagnostic catheterization and was also influenced by the revascularization “culture” at the treating hospital.
The physician performing the diagnostic catheterization and the treating hospital were strong independent predictors of the mode of revascularization. Opportunities exist to improve transparency and consistency around the decision-making process for coronary revascularization, most notably among patients with non-emergent multivessel disease.
PMCID: PMC3273505  PMID: 22158396
14.  Effect of marriage on duration of chest pain associated with acute myocardial infarction before seeking care 
Coronary artery disease is the most common cause of death in the Western world, and being married decreases the risk of death from cardiovascular causes. We aimed to determine whether marital status was a predictor of the duration of chest pain endured by patients with acute myocardial infarction before they sought care and whether the patient’s sex modified the effect.
We conducted a retrospective, population-based cohort analysis of patients with acute myocardial infarction admitted to 96 acute care hospitals in Ontario, Canada, from April 2004 to March 2005. We excluded patients who did not experience chest pain. Using multivariable regression analyses, we assessed marital status in relation to delayed presentation to hospital (more than six hours from onset of pain), both overall and stratified by sex. In patients who reported the exact duration of chest pain, we assessed the effect of marital status on the delay in seeking care.
Among 4403 eligible patients with acute myocardial infarction, the mean age was 67.3 (standard deviation 13.6) years, and 1486 (33.7%) were women. Almost half (2037 or 46.3%) presented to a hospital within two hours, and 3240 (73.6%) presented within six hours. Overall, 75.3% (2317/3079) of married patients, 67.9% (188/277) of single patients, 68.5% (189/276) of divorced patients and 70.8% (546/771) of widowed patients presented within six hours of the onset of chest pain. Being married was associated with lower odds of delayed presentation (odds ratio [OR] 0.46, 95% confidence interval [CI] 0.30–0.71, p < 0.001) relative to being single. Among men, the OR was 0.35 (95% CI 0.21–0.59, p < 0.001), whereas among women the effect of marital status was not significant (OR 1.36, 95% CI 0.49–3.73, p = 0.55).
Among men experiencing acute myocardial infarction with chest pain, being married was associated with significantly earlier presentation for care, a benefit that was not observed for married women. Earlier presentation for medical care appears to be one reason for the observed lower risk of cardiovascular death among married men, relative to their single counterparts.
PMCID: PMC3176841  PMID: 21768255
15.  Amiodarone-induced thyroid dysfunction: brand-name versus generic formulations 
Amiodarone is associated with dysfunction of the thyroid. Concerns have arisen regarding the potential for adverse effects with generic formulations of amiodarone. We evaluated and compared the risk of thyroid dysfunction between patients using brand-name versus generic formulations of amiodarone and identified risk factors for thyroid dysfunction.
We conducted a retrospective cohort study of patients with atrial fibrillation aged 66 years and older. We used administrative databases that linked information on demographics and clinical characteristics, claims for prescription drugs and discharges from hospital. We estimated thyroid dysfunction using person-year incidence.
Of the 60 220 patients in the cohort, 2804 (4.7%) used the brand-name formulation of amiodarone and 6278 (10.4%) used the generic formulation. Baseline characteristics between these two groups were comparable. The median maintenance dose of amiodarone was 200 mg/d for both groups. The total incidence rate for thyroid dysfunction was 14.1 per 100 person-years for both formulations. The mean time to clinical dysfunction of the thyroid was 4.32 years for the brand-name formulation and 4.09 years for the generic formulation. In a multivariate analysis, there was no significant difference in the incidence rates of thyroid dysfunction between the generic and brand formulations (hazard ratio 0.97, 95% confidence interval 0.87–1.08). Factors associated with an increased risk of thyroid dysfunction were being a woman, increasing age and having chronic obstructive pulmonary disease.
In this population-based study, we saw no difference between brand-name and generic formulations of amiodarone in terms of incidence of thyroid dysfunction.
PMCID: PMC3168665  PMID: 21746822
16.  Validation of physician billing and hospitalization data to identify patients with ischemic heart disease using data from the Electronic Medical Record Administrative data Linked Database (EMRALD) 
The Canadian Journal of Cardiology  2010;26(7):e225-e228.
Reporting of ischemic heart disease (IHD) prevalence in Canada has been based on self-report or patients presenting to hospital. However, IHD often presents and can be managed in the outpatient setting.
To determine whether the combination of hospital data and physician billings could accurately identify patients with IHD.
A random sample of 969 adult patients from the Electronic Medical Record Administrative data Linked Database (EMRALD) – an electronic medical record database of primary care physicians in Ontario linked to administrative data for the province of Ontario – was used. A number of combinations of physician billing and hospital discharge abstracts were tested to determine the accuracy of using administrative data to identify IHD patients.
Two physician billings within a one-year period (with one of the billings by a specialist or a family physician in a hospital or emergency room setting) or a hospital discharge abstract gave a sensitivity of 77.0% (95% CI 68.2% to 85.9%), a specificity of 98.0% (95% CI 97.0% to 98.9%), a positive predictive value of 78.8% (95% CI 70.1% to 87.5%), a negative predictive value of 97.7% (95% CI 96.8% to 98.7%) and a kappa of 0.76 (95% CI 0.68 to 0.83).
A combination of physician billing and hospital discharge abstracts can be used to identify patients with IHD. Population prevalence of IHD can be measured using administrative data.
PMCID: PMC2950731  PMID: 20847968
Administrative data; Ischemic heart disease; Validation
17.  The effect of a charted history of depression on emergency department triage and outcomes in patients with acute myocardial infarction 
Patients with acute myocardial infarction may have worse outcomes if they also have a history of depression. The early management of acute myocardial infarction is known to influence outcomes, and patients with a coexisting history of depression may be treated differently in the emergency department than those without one. Our goal was to determine whether having a charted history of depression was associated with a lower-priority emergency department triage score and worse performance on quality-of-care indices.
We conducted a retrospective population-based cohort analysis involving patients with acute myocardial infarction admitted to 96 acute care hospitals in the province of Ontario from April 2004 to March 2005. We calculated the adjusted odds of low-priority triage (Canadian Emergency Department Triage and Acuity Scale score of 3, 4 or 5) for patients with acute myocardial infarction who had a charted history of depression. We compared these odds with those for patients having a charted history of asthma or chronic obstructive pulmonary disease (COPD). Secondary outcome measures were the odds of meeting benchmark door-to-electrocardiogram, door-to-needle and door-to-balloon times.
Of 6784 patients with acute myocardial infarction, 680 (10.0%) had a past medical history of depression documented in their chart. Of these patients, 39.1% (95% confidence interval [CI] 35.3%–42.9%) were assigned a low-priority triage score, as compared with 32.7% (95% CI 31.5%–33.9%) of those without a charted history of depression. The adjusted odds of receiving a low-priority triage score with a charted history of depression were 1.26 (p = 0.01) versus 0.88 (p = 0.23) with asthma and 1.12 (p = 0.24) with COPD. For patients with a charted history of depression, the median door-to-electrocardiogram time was 20.0 minutes (v. 17.0 min for the rest of the cohort), median door-to-needle time was 53.0 (v. 37.0) minutes, and median door-to-balloon time was 251.0 (v. 110.0) minutes. The adjusted odds of missing the benchmark time with a charted history of depression were 1.39 (p < 0.001) for door-to-electrocardiogram time, 1.62 (p = 0.047) for door-to-needle time and 9.12 (p = 0.019) for door-to-balloon time.
Patients with acute myocardial infarction who had a charted history of depression were more likely to receive a low-priority emergency department triage score than those with other comorbidities and to have worse associated performance on quality indicators in acute myocardial infarction care.
PMCID: PMC3071386  PMID: 21398248
18.  Secular trends in acute coronary syndrome hospitalization from 1994 to 2005 
Acute coronary syndrome (ACS) is one of the most frequent reasons for hospitalization worldwide. Although substantial advances have been made in the prevention and treatment of coronary artery disease, their impact on the rates of ACS hospitalization is unclear.
Data from the Canadian Institute for Health Information Discharge Abstract Database were used to estimate secular trends in ACS hospitalization. A total of 1.3 million ACS hospitalizations in Canada from April 1, 1994, to March 31, 2006, were examined. Overall hospitalization rates were standardized for age and sex using 1991 Canadian census data, and hospitalization rates were also stratified by age group, sex and Canadian province to assess trends in each subgroup.
The Canadian age- and sex-standardized ACS hospitalization rate was 508 per 100,000 persons in 1994, and 317 per 100,000 persons in 2005 – a relative reduction of 37.8% and an average annual relative reduction of 3.9% per year. Declines in ACS hospitalization rates were observed among men (annual relative reduction 3.9%, relative reduction 39.0%) and women (annual relative reduction 3.8%, relative reduction 35.8%). Declining trends were also observed among patients of different age groups and among patients hospitalized across all Canadian provinces.
Over the past decade, a substantial decline in ACS hospitalization rates occurred, which has not been previously observed. This finding is likely due to improvements in primary and secondary prevention of coronary artery disease. The present study’s data should provide important insights and guidance for future health care planning in Canada.
PMCID: PMC2851466  PMID: 20352132
Acute coronary syndrome; Hospitalization rates; Secular trends
19.  The potential economic impact of restricted access to angiotensin-receptor blockers 
The use of angiotensin-receptor blockers increased by more than 4000% in Canada from 1996 to 2006. The benefit of these medications over angiotensin-converting-enzyme (ACE) inhibitors has not been proven aside from a reduction in dry cough. We estimated the potential cost savings that might have been achieved had access to angiotensin-receptor blockers been restricted.
We performed a cost-minimization analysis with a decision-tree model using a societal perspective over a one-year period. Sources of data for model parameters included IMS Health Canada data collected from one-third of all retail pharmacies for the cost and use of angiotensin-receptor blockers and ACE inhibitors in each province, as well as published studies for administrative costs and incidence of dry cough. We used Monte Carlo simulations with 10 000 iterations to test the impact of several model parameters (e.g., drug prices, administrative costs and the incidence of dry cough). All data are in 2006 Canadian dollars.
A policy that would have restricted access to angiotensin-receptor blockers might have saved more than $77 million in Canada in 2006. The simulations yielded similar savings for the year (mean $58.3 million, 95% confidence interval $29.3 million to $90.8 million). Every simulation showed a cost savings.
Had access to angiotensin-receptor blockers been restricted, the potential cost savings to the Canadian health care system might have been more than $77 million in 2006, likely without any adverse effect on cardiovascular health.
PMCID: PMC3042476  PMID: 21262939
20.  Cardiovascular disease among South Asians 
PMCID: PMC2934812
21.  Anticoagulation after Anterior Myocardial Infarction and the Risk of Stroke 
PLoS ONE  2010;5(8):e12150.
Survivors of anterior MI are at increased risk for stroke with predilection to form ventricular thrombus. Commonly patients are discharged on dual antiplatelet therapy. Given the frequency of early coronary reperfusion and risk of bleeding, it remains uncertain whether anticoagulation offers additional utility. We examined the effectiveness of anticoagulation therapy for the prevention of stroke after anterior MI.
Methods and Findings
We performed a population-based cohort analysis of 10,383 patients who survived hospitalization for an acute MI in Ontario, Canada from April 1, 1999 to March 31, 2001. The primary outcome was four-year ischemic stroke rates compared between anterior and non-anterior MI patients. Risk factors for stroke were assessed by multivariate Cox proportional-hazards analysis. Warfarin use was determined at discharge and followed for 90 days among a subset of patients aged 66 and older (n = 1483). Among the 10,383 patients studied, 2,942 patients survived hospitalization for an anterior MI and 20% were discharged on anticoagulation therapy. Within 4 years, 169 patients (5.7%) were admitted with an ischemic stroke, half of which occurred within 1-year post-MI. There was no significant difference in stroke rate between anterior and non-anterior MI patients. The use of warfarin up to 90 days was not associated with stroke protection after anterior MI (hazard ratio [HR], 0.68; 95% confidence interval [CI], 0.37–1.26). The use of angiotensin-converting-enzyme inhibitors (HR, 0.65; 95% CI, 0.44–0.95) and beta-blockers (HR, 0.60; 95% CI, 0.41–0.87) were associated with a significant decrease in stroke risk. There was no significant difference in bleeding-related hospitalizations in patients who used warfarin for up to 90 days post-MI.
Many practitioners still consider a large anterior-wall MI as high risk for potential LV thrombus formation and stroke. Among a cohort of elderly patients who survived an anterior MI there was no benefit from the use of warfarin up to 90 days post-MI to prevent ischemic stroke. Our data suggests that routine anticoagulation of patients with anterior-wall MI may not be indicated. Prospective randomized trials are needed to determine the optimal antithrombin strategy for preventing this common and serious adverse outcome.
PMCID: PMC2921337  PMID: 20730096
Circulation  2009;119(24):3070-3077.
The contributions of risk factors and disease etiology to heart failure with preserved ejection fraction (HFPEF) vs. heart failure with reduced ejection fraction (HFREF) have not been fully explored.
Methods and Results
We examined clinical characteristics and risk factors at time of heart failure (HF) onset, and long-term survival in Framingham Heart Study participants according to left ventricular ejection fraction ≤45% (n=314, 59%) vs. >45% (n=220, 41%) and hierarchical etiologic classification. HF was attributed to coronary heart disease (CHD) in 278 participants (52%), valvular heart disease in 42 (8%), hypertension in 140 (26%), or other/unknown etiologies in 74 (14%). Multivariable predictors of HFPEF (vs. HFREF) included elevated systolic blood pressure (odds ratio [OR]=1.13 per 10 mmHg, 95% CI; 1.04–1.22), atrial fibrillation (OR=4.23, 95% CI; 2.38–7.52), and female sex (OR=2.29, 95% CI; 1.35–3.90). Conversely, prior myocardial infarction (OR=0.32, 95% CI; 0.19–0.53) or left bundle-branch block QRS morphology (OR=0.21, 95% CI; 0.10–0.46) reduced the odds of HFPEF. Long-term prognosis was grim with a median survival of 2.1 years (5-year mortality rate: 74%), and was equally poor in men and women with HFREF or HFPEF.
Among community patients with new-onset HF, there are differences in etiology and time-of-onset clinical characteristics between those with HFPEF versus HFREF. In people with HFREF, mortality is increased when CHD is the underlying etiology. These findings suggest that HF with reduced vs. preserved left ventricular systolic function are partially distinct entities, with potentially different approaches to early detection and prevention.
PMCID: PMC2775498  PMID: 19506115
heart failure; epidemiology; mortality; coronary artery disease; left ventricular function
23.  Comparison of cardiovascular risk profiles among ethnic groups using population health surveys between 1996 and 2007 
Although people of South Asian, Chinese and black ethnic backgrounds represent about 60% of the world’s population, most knowledge of cardiovascular risk is derived from studies conducted in white populations. We conducted a large, population-based comparison of cardiovascular risk among people of white, South Asian, Chinese and black ethnicity living in Ontario, Canada.
We examined the age- and sex-standardized prevalence of eight cardiovascular risk factors, heart disease and stroke among 154 653 white people, 3364 South Asian people, 3038 Chinese people and 2742 black people. For this study, we pooled respondent data from five cross-sectional health surveys conducted between 1996 and 2007: the National Population Health Survey of 1996 and the Canadian Community Health Survey, versions 1.1, 2.1, 3.1 and 4.1.
The four ethnic groups varied considerably in the prevalence of the four major cardiovascular risk factors that we examined: for smoking, South Asian 8.6%, Chinese 8.7%, black 11.4% and white 24.8%; for obesity, Chinese 2.5%, South Asian 8.1%, black 14.1% and white 14.8%; for diabetes mellitus, white 4.2%, Chinese 4.3%, South Asian 8.1% and black 8.5%; and for hypertension, white 13.7%, Chinese 15.1%, South Asian 17.0% and black 19.8%. The prevalence of heart disease ranged from a low of 3.2% in the Chinese population to a high of 5.2% in the South Asian population, and the prevalence of stroke ranged from a low of 0.6% in the Chinese population to a high of 1.7% in the South Asian population. Although the black population had the least favourable cardiovascular risk factor profile overall, this group had a relatively low prevalence of heart disease (3.4%).
Ethnic groups living in Ontario had striking differences in cardiovascular risk profiles. Awareness of these differences may help in identifying priorities for the development of cardiovascular disease prevention programs for specific ethnic groups.
PMCID: PMC2871219  PMID: 20403888
24.  Surname lists to identify South Asian and Chinese ethnicity from secondary data in Ontario, Canada: a validation study 
Surname lists are useful for identifying cohorts of ethnic minority patients from secondary data sources. This study sought to develop and validate lists to identify people of South Asian and Chinese origin.
Comprehensive lists of South Asian and Chinese surnames were reviewed to identify those that uniquely belonged to the ethnic minority group. Surnames that were common in other populations, communities or ethnic groups were specifically excluded. These surname lists were applied to the Registered Persons Database, a registry of the health card numbers assigned to all residents of the Canadian province of Ontario, so that all residents were assigned to South Asian ethnicity, Chinese ethnicity or the General Population. Ethnic assignment was validated against self-identified ethnicity through linkage with responses to the Canadian Community Health Survey.
The final surname lists included 9,950 South Asian surnames and 1,133 Chinese surnames. All 16,688,384 current and former residents of Ontario were assigned to South Asian ethnicity, Chinese ethnicity or the General Population based on their surnames. Among 69,859 respondents to the Canadian Community Health Survey, both lists performed extremely well when compared against self-identified ethnicity: positive predictive value was 89.3% for the South Asian list, and 91.9% for the Chinese list. Because surnames shared with other ethnic groups were deliberately excluded from the lists, sensitivity was lower (50.4% and 80.2%, respectively).
These surname lists can be used to identify cohorts of people with South Asian and Chinese origins from secondary data sources with a high degree of accuracy. These cohorts could then be used in epidemiologic and health service research studies of populations with South Asian and Chinese origins.
PMCID: PMC2877682  PMID: 20470433
25.  Publicly reported provider outcomes: The concerns of cardiac surgeons in a single-payer system 
Provider outcomes reports are an important part of quality improvement efforts. The positive and negative impact of such reports on the delivery of care has not been extensively explored.
A survey of Ontario cardiac surgeons was performed in September 2003 to understand their concerns regarding performance reports. The questionnaire addressed the use of evidence-based practices, the impact of public-provider profiling on clinical practice and the improvement of current report cards. The survey was conducted with the distribution of a fiscal 2000/2001 cardiac surgery report card.
There was a 95% (52 of 55 cardiac surgeons) survey response rate, of which 80% were high-volume surgeons with a case volume of more than 200 cases per year. Seventy-four per cent of surgeons had more than five years of experience. The majority of surgeons believed that performance reports influenced cardiologist referrals (84%) and patient choices (80%). A minority (48%) of surgeons believed that the reporting of in-hospital mortality was very or extremely useful, but a majority (83%) believed mortality rates indicated the relative performance of a cardiac surgeon. The majority of surgeons believed that routine upcoding of data (84%) and inadequate risk adjustment (75%) were weaknesses of present performance reports. Surgeons were divided regarding whether the institutional performance should continue to be publicly reported (51% agreed with public reporting).
In a single-payer system, performance reports breed provider concerns similar to those seen in market-driven systems including high-risk patient avoidance and upcoding of data. Regardless, providers recognize that institutional performance reports, irrespective of public or confidential reporting, are important in continuous quality improvement.
PMCID: PMC2691878  PMID: 19148340
Cardiac surgery; Public performance reports; Quality of care; Survey

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