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Institute for Clinical Evaluative Sciences, Toronto, Ontario, CanadaSchulich Heart Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario, CanadaInstitute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada
It is unknown how the contemporary burden of atherosclerotic cardiovascular disease (ASCVD) compares with historical trends.
As part of the Cardiovascular Health in Ambulatory Care Research Team “big data” initiative, we used information from multiple population-based databases to study 20-year temporal trends in hospitalizations and deaths from ASCVD. We calculated hospitalization rates for 6 ASCVD events (acute myocardial infarction, unstable angina, stroke, transient ischemic attack, peripheral arterial disease, and congestive heart failure) and death rates resulting from ischemic heart disease, cerebrovascular disease and circulatory and noncirculatory causes in adults aged 20-105 years in Ontario, Canada from 1994-2014 (to 2012 for deaths).
The overall age-standardized composite rate of hospitalization for the 6 conditions or circulatory deaths declined 49.2% in men (from 1533.4 per 100,000 in 1994 to 778.3 per 100,000 in 2012) and 49.9% in women (from 1191.2 per 100,000 in 1994 to 596.2 per 100,000 in 2012). The annual rates of decline were least evident among those aged 20-49 years for both sexes. The overall self-reported prevalence of Ontarians living with heart disease or stroke, or both, declined nonsignificantly (P for trend = 0.19), from 7.7% to 7.1% for men, and significantly (P for trend = 0.01), from 7.3% to 5.8% for women, from 2001-2012.
Striking declines in hospitalizations and deaths from ASCVD were observed in Ontario from 1994-2014. However, the limited progress observed in younger Canadians highlights the need for ongoing efforts aimed at preventing and treating ASCVDs and their associated risk factors.
On ignore quel est le fardeau actuel de la maladie cardiovasculaire athérosclérotique (MCVAS) par rapport aux tendances historiques.
Dans le cadre de l’initiative « big data » de CANHEART (Cardiovascular Health in Ambulatory Care Research Team), nous avons fait appel aux données de diverses bases de données représentatives de populations afin d’établir la tendance au chapitre des hospitalisations et des décès associés à la MCVAS sur 20 ans. Nous avons calculé le taux d’hospitalisation pour six événements de la MCVAS (infarctus aigu du myocarde, angine instable, accident vasculaire cérébral (AVC), ischémie cérébrale transitoire, maladie artérielle périphérique et insuffisance cardiaque congestive) ainsi que le taux de mortalité associé à la cardiopathie ischémique, la maladie vasculaire cérébrale ainsi que les causes circulatoires et non circulatoires chez les adultes âgés entre 20 et 105 ans en Ontario, au Canada, entre 1994 et 2014 (2012 pour les décès).
Le taux composite global normalisé en fonction de l’âge pour les six événements ou les décès de causes circulatoires a diminué de 49,2 % chez les hommes (de 1533,4 pour 100 000 personnes en 1994 à 778,3 pour 100 000 personnes en 2012) et de 49,9 % chez les femmes (de 1191,2 par 100 000 personnes en 1994 à 596,2 par 100 000 personnes en 2012). Le taux de diminution annuel de tels événements était cependant moins important pour la tranche des 20 à 49 ans des deux sexes. Entre 2001 et 2012, la prévalence globale auto rapportée des Ontariens disant vivre avec une maladie du coeur ou un AVC ou les deux a aussi diminué, mais pas de manière significative (p pour la tendance = 0,19), soit de 7,7 % à 7,1 % chez les hommes, tandis qu’elle a diminué de manière significative chez les femmes (p pour la tendance = 0,01), soit de 7,3 % à 5,8 %.
En Ontario, on a observé une diminution remarquable du taux d’hospitalisation et du taux de décès des suites de la MCVAS entre 1994 et 2014. Cependant, les progrès limités à ce chapitre relevés chez les Canadiens plus jeunes indiquent qu’il faut poursuivre les efforts visant à prévenir et à traiter la MCVAS et les facteurs de risque qui y sont associés.
Atherosclerotic cardiovascular disease (ASCVD) is a leading cause of morbidity and mortality in Canada. Although a 30.0% decline in the age- and sex-standardized cardiovascular disease (CVD) mortality rate in Canada between 1994 and 2004 has been reported,
The potentially large economic and societal burden that ASCVD poses makes ascertaining and understanding temporal trends in hospitalization and death rates from ASCVD important for health system planners, policy makers, and clinicians to evaluate progress in combatting ASCVD and make decisions about allocation of limited health system resources.
In the present study, we examined temporal trends in hospitalization rates for 6 major ASCVD conditions (acute myocardial infarction [AMI], unstable angina, stroke, transient ischemic attack [TIA], peripheral arterial disease, and congestive heart failure [CHF]) in Ontario, Canada among those aged 20-105 years between 1994 and 2014, as well as trends in mortality rates from ischemic heart disease (IHD), cerebrovascular disease (CBVD), circulatory diseases, and noncirculatory diseases (comprises all noncardiovascular deaths) between 1994 and 2012. The aforementioned conditions are among the most frequent causes of hospitalization and deaths in Canada. This study is part of the Cardiovascular Health in Ambulatory Care Research Team (CANHEART) “big data” initiative (http://www.canheart.ca). The CANHEART initiative uses large population-based health databases in Ontario in an effort to measure and improve the quality of cardiovascular care in Ontario.
We used several population-based health administrative and vital statistic databases to conduct this study. Hospitalization rates for the 6 ASCVD conditions of interest as the most responsible diagnosis were determined using records in the Canadian Institute for Health Information (CIHI) hospital Discharge Abstract Database (DAD). Mortality and cause of death data up to 2012 were identified using the Registrar General of Ontario's vital statistic database. Later data were not available at the time of this study. Revascularization procedures, namely, percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) were identified from the CIHI DAD and Same Day Surgery databases. International Classification of Diseases, Ninth Revision (ICD-9) and International Classification of Diseases, Tenth Revision (ICD-10) codes used to identify hospitalization diagnoses and death causes and the Canadian Classification of Procedure and Canadian Classification of Health Interventions codes used to identify revascularization procedures, are shown in Supplemental Table S1.
Ontario population counts were obtained from Statistics Canada census data.
To obtain information on the self-reported prevalence of stroke and heart disease, we used the Canadian Community Health Survey (CCHS) cycles 2001, 2003, 2005, 2007-2008, 2009-2010, and 2011-2012. The CCHS is conducted by Statistics Canada and is a large, ongoing, population-based survey of approximately 130,000 Canadians in the general population in every 2-year cycle.
For this study, we focused on 2 survey questions—whether the respondent self-reported heart disease and if he/she reported suffering from the effects of a stroke.
We calculated yearly sex-specific, age-standardized rates of hospitalizations and deaths for each ASCVD condition and revascularization procedure among Ontarians 20-105 years of age (20-102 years for the CCHS). Rates were calculated as the sex- and year-specific total counts identified from the appropriate databases divided by the sex- and year-specific population counts reported in Statistics Canada's census data and standardized to the 2006 Ontario census population to allow for comparisons across years. If an individual had multiple hospitalizations for the same condition in a given year, each hospitalization was counted. However, transfers between hospitals were counted as 1 hospitalization. Sex-stratified, age-specific rates of hospitalizations for AMI, stroke, CHF, and a composite measure of hospitalization for 1 of the 6 ASCVD events or death from circulatory diseases was also computed for 4 age strata: 20-49, 50-64, 65-74, and 75+ years. For the composite measure, only 1 event per year for each individual was counted. Self-reported prevalence of outcomes using CCHS data were weighted using Statistics Canada survey weights to obtain weighted estimates representative of the population.
The average annual rate of change and the relative and absolute change in rates between the first and last years were also determined, with their confidence intervals (CIs) obtained using bootstrapping techniques. Testing for time trends in rates was conducted by computing Kendall's tau-b correlation coefficient and associated P value.
Trend differences by sex were examined using linear regression including year and sex interaction terms as predictors. Similarly, year-age group interaction terms were included in sex-specific regression models to determine if trends in individuals younger than 50 years differed from trends in individuals in each of the other age groups. Statistical significance was assessed at P < 0.05.
All data were analyzed at the Institute for Clinical Evaluative Sciences in Toronto, Canada using SAS, version 9.3 (SAS Institute, Cary NC). This study was approved by the Research Ethics Board at Sunnybrook Health Sciences Centre.
Temporal trends in the rates of hospitalizations for the 6 ASCVD conditions are shown in Table 1 and Figure 1. Overall, an age-standardized relative reduction in hospitalizations of 54.2% (95% CI, 53.5%-54.7%) and 54.3% (95% CI, 53.6%-54.9%) was observed in men and women, respectively, between 1994 and 2014. Although significant declines (P < 0.0001) in hospitalization rates for all conditions were observed, the greatest rates of decline were for hospitalizations resulting from unstable angina, with average yearly declines of 8.1% (95% CI, 7.9%-8.3%) in men and 9.3% (95% CI, 9.0-9.5%) in women, much of which began in 2000 (Fig. 1). Hospitalization rates for TIA showed the second fastest declines, with yearly averages of 5.0% (95% CI, 4.5%-5.3%) in men and 4.7% (95% CI, 4.3%-5.0%) in women. AMI was the most frequent cause of hospitalization in men, whereas CHF was the most frequent cause in women (Table 1). Although rates of all ASCVD conditions declined, the absolute number of hospitalizations increased for some conditions, owing in part to the increase in the Ontario adult population, which grew 34% from 7.9 million in 1994 to 10.6 million in 2014.
By sex, trends in age-standardized rates were significantly different except for hospitalizations attributed to CHF, stroke, and TIA, with less pronounced absolute declines observed in women (Supplemental Table S2).
Mortality rates for circulatory diseases, including cardiovascular causes, declined 52.7% (95% CI, 51.6%-53.8%) in men and 52.8% (95% CI, 51.7%-53.9%) in women between 1994 and 2012 (Table 2; Supplemental Fig. S1). The rates of decline in deaths from IHD and CBVD were also similar for both sexes, with a steady decline of approximately 4% annually. In contrast, smaller relative reductions were observed in mortality rates attributable to noncardiovascular causes, which declined only 21.7% (95% CI, 20.4%-23.1%) in men and 8.2% (95% CI, 6.6%-9.9%) in women over this same period. The tests for trends were statistically significant for all mortality outcomes examined.
Across the study period, greater absolute declines in mortality were observed for men, with the exception of death from CBVD, with trends found to differ significantly across sex (Supplemental Table S2).
Procedure rates are shown in Figure 2 and Supplemental Table S3. A significant increase in PCI procedure volume and rate (P < 0.0001) was observed during the study period, with the greatest increases occurring between 1994 and 2006 and rates remaining relatively stable thereafter (Fig. 2). In contrast, although rates of CABG increased slightly between 1994 and the late 1990s, an average yearly decline of 1% was observed in men and women, resulting from a steady decline in the 2000s. Trends in age-standardized rates were significantly different across sex for both PCI and CABG (Supplemental Table S2).
Age-specific rates for major ASCVD events are presented in Table 3. Across the study period, the greatest observed declines in hospitalization rates for AMI and CHF were among those aged 50-64 years and those aged 65-74 years; for stroke, these declines were among those aged 65-74 years and those aged 75+ years. When average yearly declines in rates were observed among those younger than 50 years of age, they were statistically significant (P < 0.05) but modest at < 2% (Table 3). For CHF and AMI in women and stroke in men, small increases in hospitalization rates were observed in this age group, although the trends did not approach significance in the latter 2 cases (P = 0.7171 and P = 0.2047, respectively). Age-specific trends were significantly different in patients 20-49 years of age vs patients in each of the other age groups (P < 0.001).
Table 3Age- and sex-specific rates of major atherosclerotic cardiovascular events (per 100,000) in Ontarians aged 20-105 years, 1994-2012
Trends across years examined using Kendall tau-b correlation coefficient with P < 0.05 for all subgroups except AMI hospitalizations in women (P = 0.7171) and stroke hospitalizations in men (P = 0.2047) aged 20-49 years.
Rates standardized to the 2006 Ontario census population.
Ontario population aged 20+ years: 1994 = 7,915,584; 2012 = 10,323,459. Composite measure composed of 1 of either of the following: hospitalization resulting from acute myocardial infarction, stroke, peripheral arterial disease, congestive heart failure, unstable angina or transient ischemic attack, or death from circulatory diseases.
∗ Trends across years examined using Kendall tau-b correlation coefficient with P < 0.05 for all subgroups except AMI hospitalizations in women (P = 0.7171) and stroke hospitalizations in men (P = 0.2047) aged 20-49 years.
† Rates standardized to the 2006 Ontario census population.
Significant declines in the age-standardized composite rates of hospitalization for 1 of the 6 ASCVD conditions or deaths resulting from circulatory diseases was observed from 1994-2012 (Supplemental Fig. S2; P < 0.0001). Declines in relative rates were comparable for both sexes, with a 49.2% decrease from 1533.4 per 100,000 in 1994 to 778.3 per 100,000 in 2012 observed in men and a 49.9% decrease from 1191.2 per 100,000 in 1994 to 596.2 per 100,000 in 2012 in women (Table 3). Consistent with some individual ASCVD outcomes, average yearly declines during the study period were least pronounced in those aged 20-49 years and greatest in those aged 50-64 years and 65-74 years (Table 3).
Comparing 2001 and 2012, the self-reported prevalence of Ontarians living with heart disease or stroke, or both, declined nonsignificantly (P for trend = 0.19) from 7.7% to 7.1% for men and significantly (P for trend = 0.01) from 7.3% to 5.8% for women. The annual prevalence of self-reported heart disease decreased among both men and women as well as self-reports for stroke among women, with only the prevalence of heart disease in women being statistically significant (Table 4). A nonsignificant average yearly increase of 1.1% (95% CI, −4.7% to 9.4%) was observed in men for self-reported stroke. The absolute burden of self-reported heart disease and stroke increased because of population growth.
Trends in prevalence rates across Canadian Community Health Survey cycles examined using Kendall tau-b correlation coefficient and associated P value.
Number of events
Average yearly change, % (95% CI)
P for trend
−1.4 (−3.8 to 1.6)
1.1 (−4.7 to 9.4)
−1.3 (−3.4 to 1.5)
−5.4 (−7.8 to −2.2)
−0.3 (−6.2 to 7.2)
−4.3 (−6.7 to −1.6)
Estimates weighted using Statistics Canada survey weights. The composite measure is composed of self-reporting at least 1 of the following: having heart disease or experiencing the effects of a stroke.
CI, confidence interval.
∗ Rates standardized to the 2006 Ontario census population.
† Trends in prevalence rates across Canadian Community Health Survey cycles examined using Kendall tau-b correlation coefficient and associated P value.
As part of the CANHEART “big data” initiative, we studied contemporary temporal trends in hospitalizations and deaths from ASCVD conditions over a 20-year period in Ontario. Striking improvements were observed for most conditions, with an overall decline of approximately 50% in both hospitalizations and cardiovascular deaths, driven mostly by declines among those 50-74 years of age. Reductions in hospitalization rates were most notable for unstable angina and TIAs, which declined by > 80% and 60%, respectively. Declines in ASCVD hospitalization and death rates were accompanied by a slight decrease in the self-reported prevalence of Ontarians living with heart disease or stroke, or both. In contrast, declines in rates of noncirculatory deaths were less pronounced. Although our overall results are encouraging, there are inequalities in CVD declines, with improvements least evident, and in some cases nonexistent, among Ontarians younger than 50 years of age, which remains an area of ongoing concern.
Our findings of decreasing hospitalization and death rates from ASCVD are consistent with a number of previous studies conducted in Canada, the United States, and Western European countries, although most of these studies were over a shorter time frame and did not include all 6 ASCVD conditions examined in this study.
similar to the average annual declines in deaths resulting from circulatory disease of 4.1% that we observed. In another study in the United States, a 43% relative increase in stroke among those 25-44 years of age and a 4.7% increase among those 45-69 years of age from 2000-2010 was observed.
Our study also found hospitalization rates for stroke in men to be rising at a modest average annual rate in the youngest age group of patients 20-49 years of age.
Although a detailed analysis examining potential contributing factors to our findings is outside the scope of this article, studies conducted in Ontario and similar jurisdictions suggest that the reasons likely include a combination of declines in smoking rates, improved control of high blood pressure, and higher use of statin drugs and other lipid-lowering therapies.
Advances in treatments over the past 2 decades for conditions such as acute coronary syndromes, cerebrovascular events, and CHF are also likely to be contributory. Despite our positive findings, obesity and diabetes rates in Ontario and elsewhere among younger individuals are rising,
which may partially offset advances in ASCVD prevention and treatment, resulting in the significantly slower declines observed in this group. The lack of progress observed in event rates among Ontarians 20-49 years of age are particularly noteworthy because event rates in this group will become increasingly important as they age. The potential reasons for our findings that trends differed across men and women for some outcomes should be explored in future studies.
The population-based nature of the databases used in this study and the scope of outcomes examined enabled us to conduct a comprehensive examination of cardiovascular population health and disease burden in Ontario. However, we recognize some important limitations. First, our analyses relied primarily on ICD-9 and ICD-10 codes reported in administrative databases. Although most codes used in our study have been previously validated using chart reviews, clinical registries, and other data sources,
reporting may be subject to miscoding. Our findings are also a reflection of trends in Ontario, Canada's largest province, and may not be generalizable to other provinces in Canada. Among Canadian provinces, where an “east to west” gradient has been observed in CVD death rates and self-reported heart disease, Ontario has historically ranked in the middle.
Due to limitations of the questions posed in the CCHS, except for stroke, only prevalence rates of heart disease overall could be determined. Since prevalence estimates in this study were from self-reported data, response bias may have influenced the results.
Our findings that the overall burden of most ASCVD conditions is on the decline in Ontario suggests that advancements in screening, prevention, and treatment of ASCVD appear to have had an important public health and health systems impact over the past 2 decades. These results are encouraging but should not be grounds for complacency, because ASCVD remains among the leading causes of death in Canada,
Furthermore, in light of our finding that the declines in rates for younger Ontarians were modest, and in certain sex/age groups higher in more recent years than they were in 1994, the need for continued investment in improving ASCVD outcomes is important to ensure the progress made thus far continues.
Parts of this material are based on data and information compiled and provided by the Canadian Institute for Health Information (CIHI) and Service Ontario. The analyses, conclusions, opinions, and statements expressed herein are those of the authors and are independent from the Institute for Clinical Evaluative Sciences (ICES), funding sources, CIHI and Service Ontario. No endorsement by ICES, the Ontario Ministry of Health and Long-Term Care (MOHLTC), CIHI, or Service Ontario is intended or should be inferred.
This work was supported by ICES, an operating grant from the Institute of Circulatory and Respiratory Health (ICRH)—Canadian Institutes of Health Research (CIHR) Chronic Diseases Team (Grant No. TCA 118349), and the Foundation Scheme (Grant No. FDN 143313). ICES is funded by an annual grant from the Ontario MOHLTC. J.V.T. is supported by a Tier 1 Canada Research Chair in Health Services Research and an Eaton Scholar award from the Department of Medicine, University of Toronto.
The authors have no conflicts of interest to disclose.