Cynthia Robitaille

Hypertension prevalence, awareness, treatment and control in national surveys from England, the USA and Canada, and correlation with stroke and ischaemic heart disease mortality: a cross-sectional study.

Objective Comparison of recent national survey data on prevalence, awareness, treatment and control of hypertension in England, the USA and Canada, and correlation of these parameters with each country stroke and ischaemic heart disease (IHD) mortality. Design Non-institutionalised population surveys. Setting and participants England (2006 n=6873), the USA (2007–2010 n=10 003) and Canada (2007–2009 n=3485) aged 20–79 years. Outcomes Stroke and IHD mortality rates were plotted against countries’ specific prevalence data. Results Mean systolic blood pressure (SBP) was higher in England than in the USA and Canada in all age–gender groups. Mean diastolic blood pressure (DBP) was similar in the three countries before age 50 and then fell more rapidly in the USA, being the lowest in the USA. Only 34% had a BP under 140/90 mm Hg in England, compared with 50% in the USA and 66% in Canada. Prehypertension and stages 1 and 2 hypertension prevalence figures were the highest in England. Hypertension prevalence (≥140 mm Hg SBP and/or ≥90 mm Hg DBP) was lower in Canada (19·5%) than in the USA (29%) and England (30%). Hypertension awareness was higher in the USA (81%) and Canada (83%) than in England (65%). England also had lower levels of hypertension treatment (51%; USA 74%; Canada 80%) and control (<140/90 mm Hg; 27%; the USA 53%; Canada 66%). Canada had the lowest stroke and IHD mortality rates, England the highest and the rates were inversely related to the mean SBP in each country and strongly related to the blood pressure indicators, the strongest relationship being between low hypertension awareness and stroke mortality. Conclusions While the current prevention efforts in England should result in future-improved figures, especially at younger ages, these data still show important gaps in the management of hypertension in these countries, with consequences on stroke and IHD mortality.

Diagnosed hypertension in Canada: incidence, prevalence and associated mortality

Background: Hypertension is a leading risk factor for cardiovascular diseases. Our objectives were to examine the prevalence and incidence of diagnosed hypertension in Canada and compare mortality among people with and without diagnosed hypertension. Methods: We obtained data from linked health administrative databases from each province and territory for adults aged 20 years and older. We used a validated case definition to identify people with hypertension diagnosed between 1998/99 and 2007/08. We excluded pregnant women from the analysis. Results: This retrospective population-based study included more than 26 million people. In 2007/08, about 6 million adults (23.0%) were living with diagnosed hypertension and about 418 000 had a new diagnosis. The age-standardized prevalence increased significantly from 12.5% in 1998/99 to 19.6% in 2007/08, and the incidence decreased from 2.7 to 2.4 per 100. Among people aged 60 years and older, the prevalence was higher among women than among men, as was the incidence among people aged 75 years and older. The prevalence and incidence were highest in the Atlantic region. For all age groups, all-cause mortality was higher among adults with diagnosed hypertension than among those without diagnosed hypertension. Interpretation: The overall prevalence of diagnosed hypertension in Canada from 1998 to 2008 was high and increasing, whereas the incidence declined during the same period. These findings highlight the need to continue monitoring the effectiveness of efforts for managing hypertension and to enhance public health programs aimed at preventing hypertension.

Factors Associated With Lack of Awareness and Uncontrolled High Blood Pressure Among Canadian Adults With Hypertension

BACKGROUND Approximately 17% of Canadians with high blood pressure were unaware of their condition, and of Canadians aware of having the condition, approximately 1 in 5 have uncontrolled high blood pressure despite high rates of pharmacotherapy. The objectives of the current study are to estimate the prevalence of resistant hypertension and examine factors associated with (1) lack of awareness and (2) uncontrolled hypertension despite pharmacotherapy. METHODS Using the 2007-2009 Canadian Health Measures Survey (N = 3473, aged 20-79 years) and logistic regression, we quantified relationships between characteristics and (1) presence of hypertension, (2) lack of awareness (among those with hypertension), and (3) uncontrolled high blood pressure (among those treated for hypertension). RESULTS Older age, lowest income, and less than high school education were associated with presence of hypertension. Men (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.1-2.2) and adults < 60 years (OR, 1.7; 95% CI, 1.1-2.6) were more likely than others to be unaware. Among those aged 60+ years, women were more likely than men to have uncontrolled high blood pressure (OR, 2.4; 95% CI, 1.1-5.2) despite treatment. Elevated systolic blood pressure was the issue in over 90% of women and 80% of men with uncontrolled hypertension. Depending on the definition employed, 4.4% (95% CI, 2.4-6.4) to 7.8% (95% CI, 6.0-9.6) of the population with hypertension had resistant hypertension. CONCLUSIONS Messaging or interventions encouraging screening may be helpful for all younger Canadian adults and men; programs encouraging blood pressure control may help older women.

Prevalence of, and barriers to, preventive lifestyle behaviors in hypertension (from a national survey of Canadians with hypertension).

Patients with hypertension are advised to lower their blood pressure to <140/90 mm Hg through sustained lifestyle modification and/or pharmacotherapy. To describe the use of lifestyle changes for blood pressure control and to identify the barriers to these behaviors, the data from 6,142 Canadians with hypertension who responded to the 2009 Survey on Living With Chronic Diseases in Canada were analyzed. Most Canadians with diagnosed hypertension reported limiting salt consumption (89%), having changed the types of food they eat (89%), engaging in physical activity (80%), trying to control or lose weight if overweight (77%), quitting smoking if currently smoking (78%), and reducing alcohol intake if currently drinking more than the recommended levels (57%) at least some of the time to control their blood pressure. Men, those aged 20 to 44 years, and those with lower educational attainment and lower income were, in general, less likely to report engaging in lifestyle behaviors for blood pressure control. A low desire, interest, or awareness were commonly reported barriers to salt restriction, changes in diet, weight loss, smoking cessation, and alcohol reduction. In contrast, the most common barrier to engaging in physical activity to regulate blood pressure was the self-reported challenge of managing a coexisting physical condition or time constraints. In conclusion, programs and interventions to improve the adherence to lifestyle changes to treat hypertension may need to consider the identified barriers to lifestyle behaviors in their design.

Antihypertensive Medication Use, Adherence, Stops, and Starts in Canadians With Hypertension

BACKGROUND Some of the greatest barriers to achieving blood pressure control are perceived to be failure to prescribe antihypertensive medication and lack of adherence to medication prescriptions. METHODS Self-reported data from 6017 Canadians with diagnosed hypertension who responded to the 2008 Canadian Community Health Survey and the 2009 Survey on Living with Chronic Diseases in Canada were examined. RESULTS The majority (82%) of individuals with diagnosed hypertension reported using antihypertensive medications. The main reasons for not taking medications were either that they were not prescribed (42%) or that blood pressure had been controlled without medications (45%). Of those not taking antihypertensive medications in 2008 (n = 963), 18% had started antihypertensive medications by 2009, and of those initially taking medications (n = 5058), 5% had stopped. Of those taking medications in 2009, 89% indicated they took the medication as prescribed, and 10% indicated they occasionally missed a dose. Participants who were recently diagnosed, not measuring blood pressure at home, not having a plan to control blood pressure, or not receiving instructions on how to take medications were less likely to be taking antihypertensive medications; similar factors tended to be associated with stopping antihypertensive medication use. CONCLUSIONS Compatible with high rates of hypertension control, most Canadians diagnosed with hypertension take antihypertensive medications and report adherence. Widespread implementation of self-management strategies for blood pressure control and standardized instructions on antihypertensive medication may further optimize drug treatment.

Comparison of Diagnosed, Self-Reported, and Physically-Measured Hypertension in Canada

BACKGROUND Hypertension is a substantial health concern because it poses significant risks for cardiovascular morbidity and mortality and is highly prevalent in the population. Tracking hypertension is important because it is a risk factor for other conditions, but prevalence estimates might vary depending on the data source used. METHODS This report describes 3 national population-based data sources for estimating hypertension prevalence in Canada and discusses their strengths and weaknesses to aid in their use for policy and program planning. They are compared based on: sample coverage, case identification, and prevalence estimates. RESULTS Each source produces a different measure of hypertension prevalence, as follows: (1) diagnosed hypertension from the Canadian Chronic Disease Surveillance System (CCDSS) (2007/2008); (2) self-reported diagnosed hypertension from the Canadian Community Health Survey (CCHS) (2007-2008); and, (3) physically-measured hypertension from the Canadian Health Measures Survey (CHMS) (2007-2009). Crude rates and counts of hypertension prevalence among individuals aged 20 to 79 years of age, excluding pregnant women, are compared, resulting in prevalence ranging from 18.2% in self-report data to 20.3% in diagnosed data. The data sources differ in terms of target population, case identification, and limitations, which affects the estimates. CONCLUSIONS Each source has unique strengths and is best suited for addressing particular research questions. For example, diagnosed hypertension can be used to determine health care utilization patterns, self-reported to examine health determinants, and measured high blood pressure to improve awareness, treatment, and control. Combined, they can address multiple issues and increase our knowledge of hypertension in Canada.

Assessing the Burden of Hospitalized and Community-Care Heart Failure in Canada

BACKGROUND The surveillance of heart failure (HF) is currently conducted using either survey or hospital data, which have many limitations. Because Canada is collecting medical information in administrative health data, the present study seeks to propose methods for the national surveillance of HF using linked population-based data. METHODS Linked administrative data from 5 Canadian provinces were analyzed to estimate prevalence, incidence, and mortality rates for persons with HF between 1996/1997 and 2008/2009 using 2 case definitions: (1) 1 hospitalization with an HF diagnosis in any field (H_Any) and (2) 1 hospitalization in any field or at least 2 physician claims within a 1-year period (H_Any_2P). One hospitalization with an HF diagnosis code in the most responsible diagnosis field (H_MR) was also compared. Rates were calculated for individuals aged ≥ 40 years. RESULTS In 2008/2009, combining the 5 provinces (approximately 82% of Canadas total population), both age-standardized HF prevalence and incidence were underestimated by 39% and 33%, respectively, with H_Any when compared with H_Any_2P. Mortality was higher in patients with H_MR compared with H_Any. The degree of underestimation varied by province and by age, with older age groups presenting the largest differences. Prevalence estimates were stable over the years, especially for the H_Any_2P case definition. CONCLUSIONS The prevalence and incidence of HF using inpatient data alone likely underestimates the population rates by at least 33%. The addition of physician claims data is likely to provide a more inclusive estimate of the burden of HF in Canada.

Surveillance of ischemic heart disease should include physician billing claims: population-based evidence from administrative health data across seven Canadian provinces

BackgroundCanadian provinces and territories routinely collect health information for administrative purposes. This study used Canadian medical and hospital administrative data for population-based surveillance of diagnosed ischemic heart disease (IHD).MethodsHospital discharge abstracts and physician billing claims data from seven provinces were analyzed to estimate prevalence and incidence of IHD using three validated algorithms: a) one hospital discharge abstract with an IHD diagnosis or procedure code (1H); b) 1H or at least three physician claims within a one-year period (1H3P) and c) 1H or at least two physician claims within a one-year period (1H2P). Crude and age-standardized prevalence and incidence rates were calculated for Canadian adults aged 20 +.ResultsIHD prevalence and incidence varied by province, were consistently higher among males than females, and increased with age. Prevalence and incidence were lower using the 1H method compared to using the 1H2P or 1H3P methods in all provinces studied for all age groups. For instance, in 2006/07, crude prevalence by province ranged from 3.4%-5.5% (1H), from 4.9%-7.7% (1H3P) and from 6.0%-9.2% (1H2P). Similarly, crude incidence by province ranged from 3.7-5.9 per 1,000 (1H), from 5.0-6.9 per 1,000 (1H3P) and from 6.1-7.9 per 1,000 (1H2P).ConclusionsStudy findings show that incidence and prevalence of diagnosed IHD will be underestimated by as much as 50% using inpatient data alone. The addition of physician claims data are needed to better assess the burden of IHD in Canada.

The Canadian Chronic Disease Surveillance System: A model for collaborative surveillance

Chronic diseases have a major impact on populations and healthcare systems worldwide. Administrative health data are an ideal resource for chronic disease surveillance because they are population-based and routinely collected. For multi-jurisdictional surveillance, a distributed model is advantageous because it does not require individual-level data to be shared across jurisdictional boundaries. Our objective is to describe the process, structure, benefits, and challenges of a distributed model for chronic disease surveillance across all Canadian provinces and territories (P/Ts) using linked administrative data. The Public Health Agency of Canada (PHAC) established the Canadian Chronic Disease Surveillance System (CCDSS) in 2009 to facilitate standardized, national estimates of chronic disease prevalence, incidence, and outcomes. The CCDSS primarily relies on linked health insurance registration files, physician billing claims, and hospital discharge abstracts. Standardized case definitions and common analytic protocols are applied to the data for each P/T; aggregate data are shared with PHAC and summarized for reports and open access data initiatives. Advantages of this distributed model include: it uses the rich data resources available in all P/Ts; it supports chronic disease surveillance capacity building in all P/Ts; and changes in surveillance methodology can be easily developed by PHAC and implemented by the P/Ts. However, there are challenges: heterogeneity in administrative databases across jurisdictions and changes in data quality over time threaten the production of standardized disease estimates; a limited set of databases are common to all P/Ts, which hinders potential CCDSS expansion; and there is a need to balance comprehensive reporting with P/T disclosure requirements to protect privacy. The CCDSS distributed model for chronic disease surveillance has been successfully implemented and sustained by PHAC and its P/T partners. Many lessons have been learned about national surveillance involving jurisdictions that are heterogeneous with respect to healthcare databases, expertise and analytical capacity, population characteristics, and priorities.