Cardiovascular disease (CVD) mortality is

AJH 1997;10:1097 1102 Awareness, Treatment, and Control of Hypertension in Canada Michel R. Joffres, Parviz Ghadirian, J. George Fodor, Andres Petrasovits, Arun Chockalingam, and Pavel Hamet The Canadian Heart Health Surveys are crosssectional, population-based cardiovascular disease risk factor surveys that took place in each of the 10 Canadian provinces between 1986 and 1992. Hypertension awareness, treatment, and control status are examined. Of 23,129 randomly selected, noninstitutionalized respondents aged 18 to 74 years, 85% had four blood pressure (BP) measurements taken under standardized conditions, two at home during a home interview and two at a following clinic visit. The mean of all available measurements was used to determine hypertension status. Estimates are weighted and represent population values. Only 2% of respondents had never had their BP checked, and 73% had had their BP checked in the last 12 months. A systolic or diastolic BP > 140/90 mm Hg was found in 22% of participants (26% of men, 18% of women), representing 4.1 million Canadians. Overall, 16% of participants were Cardiovascular disease (CVD) mortality is still the leading cause of death in Canada, with 38% of mortality due to CVD. 1 Premature mortality could be improved with better control of hypertension. 2,3 A previous study 4 has treated and controlled; 23% were treated and not controlled; 19% were not treated and not controlled; and 42% were unaware of their hypertension (47% of men and 35% of women). Among hypertensives 18 to 34 years old, 64% of men and 19% of women were unaware of their hypertension. Among treated and not controlled hypertensives 63% had a mean systolic BP > 150 mm Hg, and 29% a diastolic BP > 95 mm Hg, suggesting that an important number of Canadians treated for hypertension are still at increased risk. Despite frequent interactions with the health care system, too many Canadians are still not well controlled or are unaware of their hypertension. Am J Hypertens 1997;10:1097 1102 1997 American Journal of Hypertension, Ltd. KEY WORDS: Hypertension treatment, Canadian Heart Health Survey, hypertension awareness. presented data on hypertension in nine of the 10 Canadian provinces and identified a relatively low level of hypertension control and awareness, even when using only a diastolic BP of 90 mm Hg or current treatment for defining hypertension. This article pre- Received August 15, 1996; accepted April 7, 1997. From the Department of Community Health and Epidemiology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia (MRJ); Research Centre, Centre Hospitalier Universitaire, Montréal, Québec (PG, PH); Heart Check, University of Ottawa Heart Institute, Ottawa Civic Hospital, Ottawa, Ontario (JGF); CVD Prevention Unit, Disease Prevention Division, Health Canada, Ottawa, Ontario (AP); Canadian Coalition for High Blood Pressure Prevention and Control, Orleans, Ontario (AC), Canada. The Canadian Heart Health Surveys were supported by the National Research and Development Program of Health Canada, Provincial Departments of Health, and Provincial Heart and Stroke Foundations. Address correspondence and reprint requests to Michel R. Joffres, Department of Community Health and Epidemiology, Faculty of Medicine, Dalhousie University, 5849 University Avenue, Halifax, NS B3H 4H7, Canada. 1997 by the American Journal of Hypertension, Ltd. 0895-7061/97/$17.00 Published by Elsevier Science, Inc. PII S0895-7061(97)00224-0

1098 JOFFRES ET AL AJH OCTOBER 1997 VOL. 10, NO. 10, PART 1 sents for the first time prevalence data on hypertension treatment, control, and awareness for the 10 Canadian provinces, using both systolic and diastolic BP for the definition of hypertension. METHODS In each province, sampling consisted of stratified, twostage, replicated probability samples of 2,200 adults, 18 to 74 years old, who were not living in institutions, in Native people reserves, or in military camps. Health insurance registries were used as sampling frames. They are regularly updated and contain a nearly complete listing of the target population, as almost all Canadians are covered by provincial health insurance plans. All 10 Canadian provinces participated in this joint effort from 1986 to 1992. A total of 29,855 individuals, aged 18 to 74 years, were selected as participants, and 23,129 participated in the surveys. Details of the study methodology have been published elsewhere. 5 The same methodology was used in all 10 surveys. Randomly selected subjects were contacted first by a letter then by a phone call from trained public health nurses. First, a home interview of about 40 to 60 min provided demographic and lifestyle data, and the individual s level of knowledge and awareness of CVD risk factors. Blood pressure was measured at the beginning and at the end of the interview by a trained nurse. Standardization for identification of the Korotkoff sounds followed the procedure developed for the Hypertension Detection and Follow-up Program. 6 Standard mercury sphygmomanometers, 15-in. stethoscopes, and correctly sized cuffs were used. Subjects first rested quietly for 5 min. Participants had been asked not to smoke for at least 30 min before the measurement and not to drink alcohol for at least 8 h. In a sitting position, the participant s right arm was held at heart level. When impossible to measure on the right arm, BP was measured on the left arm. The maximum inflation level was determined before the actual measurement. The first and fifth Korotkoff sounds were recorded for the systolic and diastolic BP, respectively, and for sounds continuing to 0 mm Hg, the fourth Korotkoff sound was used. Pulse was also determined. About 2 weeks later participants were invited to attend a clinic visit in which fasting blood samples, anthropometric measures, and two additional blood pressure measurements were taken. To calculate prevalence estimates the mean of four BP measurements was used in 19,728 individuals (85.3%), and the mean of two BP measurements was used in 3,171 subjects (13.7%) who did not attend the clinic. Any other available BP values were used in 212 (0.9%) participants and 18 (0.1%) had no valid BP measurements. In the present study, all reported measurements are weighted to account for the sampling design, and estimates in the tables represent population estimates. Participants were informed of the TABLE 1. PERCENTAGE DISTRIBUTION OF CANADIAN ADULTS REPORTING HAVING HAD THEIR BLOOD PRESSURE (BP) EVER MEASURED, BY AGE GROUP, AND SEX (years) Sex results of their BP measurements, and those with a diastolic BP 90 mm Hg were advised to see a physician according to the Referral Guidelines of the Canadian Hypertension Society and of the Canadian Coalition for High Blood Pressure Prevention and Control of that time period. In this study, hypertension was defined as a mean diastolic BP of 90 mm Hg or a mean systolic BP of 140 mm Hg, or current treatment with prescription medicine or nonpharmacological treatment (weight control or sodium/salt reduction). Individuals who reported having been told that they had high blood pressure, who were not treated, or who had normal blood pressure were not included in the hypertension group. Each of the 10 surveys procedures and results were independently reviewed by separate data interpretation committees and combined into the Canadian Heart Health Surveys Database. RESULTS BP Ever Measured N Yes (%) No (%) 18 34 Male 5745 94 6 Female 6040 98 2 35 64 Male 3619 99 1 Female 3741 99 1 65 74 Male 2000 100 1 Female 1971 99 1 All Male 11,364 97 3 Female 11,752 99 1 Total 23,116 98 2 Only 2% of the study subjects had never had their BP measured (3% of men and 1% of women). Men aged 18 to 34 years had the highest rate (6%) of nonmeasurement (Table 1). Of those who ever had their BP measured (Table 2), more than half (51%) had had their BP measured in the last 6 months (45% of men and 57% of women). In each age group, women had had their BP measured more often in the last 6 months than had men. The relative difference in measurement frequency was highest in the age group 18 to 34 years (men 34%, women 53%) and lowest in the age group 65 to 74 years (men 70%, women 77%). The overall prevalence of hypertension in the Canadian population was 22% (Table 3), and was higher in men (26%) than in women (18%). Hypertension prevalence increased with age and was relatively much lower in women than in men aged 18 to 34 years (2% v 11%).

AJH OCTOBER 1997 VOL. 10, NO. 10, PART 1 HYPERTENSION CONTROL IN CANADA 1099 TABLE 2. DISTRIBUTION (%) OF PERSONS BY LENGTH OF TIME SINCE LAST BLOOD PRESSURE (BP) MEASUREMENT BY AGE GROUP AND SEX Time Since Last BP Measurement (years) Sex N <6 months (%) 6 12 months (%) >12 months (%) Unknown (%) 18 34 Male 5366 34 23 42 1 Female 5920 53 26 21 1 35 64 Male 3575 49 23 28 1 Female 3722 56 22 22 1 65 74 Male 1989 70 16 14 1 Female 1960 77 11 12 1 Total Male 10,930 45 22 32 1 Female 11,602 57 22 20 1 Total 22,532 51 22 26 1 However, in the 65 to 74 age group, women had a higher hypertension prevalence than did men (58% v 56%). Twenty-one percent of the population (20% of men and 21% of women) reported having been told that they had high blood pressure at some point in the past (Table 4). There was no consistent difference among the three age groups, and a tendency for subjects to report ever having been told that they had high blood pressure increased with age. Table 5 shows that in the age group 18 to 74 years old, 42% were not aware of their hypertension, men generally being less aware of their hypertension than women (47% v 35%). The highest difference in lack of awareness between men and women was in the age group 18 to 34 years, in which 64% of men v 19% of women were not aware of their hypertension. Overall, only 16% of hypertensives (men 13%, women 20%) were treated and controlled; 23% (men 19%, women 29%) were treated and not controlled; and 19% (men 21%, women 15%) were not treated and not controlled. The highest level of treatment and control of hypertension was seen in women aged 18 to 34 years (41%), and the lowest in men (7%) of the same age group. TABLE 3. PREVALENCE OF HYPERTENSION* BY AGE AND SEX (years) Sex N Hypertension (%) 18 34 Male 5755 11 Female 6041 2 35 64 Male 3621 31 Female 3741 21 65 74 Male 2000 56 Female 1971 58 All Male 11,376 26 Female 11,753 18 Total 23,129 22 * Hypertension defined as a mean systolic BP or a mean diastolic BP 140/90 mm Hg or currently treated with a prescription medication or The majority (61%) of hypertensives reported not being treated (Table 6), and more so among men than among women in all age groups. Men aged 18 to 34 years had the highest prevalence of no treatment (88%). The reported use of prescription medication alone (18%) was higher than the combination prescription medication and nonpharmacological (15%). Overall, there was a low reported use of nonpharmacological treatment alone (6%), but in women age 18 to 34 years this proportion reached 31%. The distribution of systolic and diastolic BP among hypertensives who were not controlled is presented in Table 7. In this case, not controlled means that one of the measurements (systolic or diastolic BP) may be elevated, whereas the other may be under the cut-off point of 140/90 mm Hg. This results in some individuals being under the cut-off points for distributions of either systolic or diastolic BP in Table 7. For systolic BP, most of the uncontrolled hypertensives were in the 150 mm Hg range (63%), with a shift toward lower TABLE 4. PERCENTAGE DISTRIBUTION OF PERSONS EVER TOLD* THEY HAD HIGH BLOOD PRESSURE (BP) BY AGE GROUP AND SEX (years) Sex Yes (%) Told They Had High BP No (%) Don t Remember (%) 18 34 Male 11 88 1 Female 13 87 1 35 64 Male 25 75 1 Female 22 77 1 65 74 Male 34 65 1 Female 41 57 1 Total Male 20 79 1 Female 21 79 1 Total 21 79 1 * By a health care professional. Rows may not add to 100% because of rounding.

1100 JOFFRES ET AL AJH OCTOBER 1997 VOL. 10, NO. 10, PART 1 TABLE 5. PREVALENCE OF HYPERTENSION* AWARENESS, TREATMENT, AND CONTROL STATUS BY AGE GROUP AND SEX Hypertension Status (%) (years) Sex N Treated, Controlled Treated, Not Controlled Not Treated, Not Controlled Not Aware 18 34 Male 680 7 5 24 64 Female 197 41 13 27 19 35 64 Male 1181 14 21 22 43 Female 926 22 25 17 36 65 74 Male 1163 13 27 15 45 Female 1216 16 38 11 36 Total Male 3024 13 19 21 47 Female 2339 20 29 15 35 Total 5363 16 23 19 42 * Hypertension defined as a mean systolic BP or a mean diastolic BP 140/90 mm Hg or currently treated with a prescription medication or Rows may not add to 100% because of rounding. BP levels in the younger age groups. Although there were relatively more women with uncontrolled hypertension in the higher BP range among the 65 to 74 year age group (73% v 69%), there were more women in the lower BP range in the younger age group (70% v 57%). For diastolic BP, 45% of the population of uncontrolled hypertensives was in the 90 mm Hg range, with 26% in the 90 to 94 mm Hg range and 11% in the 100 mm Hg range. Among subjects aged 65 to 74 years, most of the population was in the 90 mm Hg range (men 64%, women 71%). Men in the age group 18 to 64 years tended to have higher diastolic BP values than did women in the same age groups. TABLE 6. PERCENTAGE DISTRIBUTION OF PERSONS BY TREATMENT TYPE, SEX, AND AGE AMONG HYPERTENSIVES* (years) Sex None Treatment (%) Prescription Medicine Only Nonpharm. Nonpharm. Only 18 34 Male 88 2 2 8 Female 46 10 13 31 35 64 Male 65 13 15 7 Female 53 19 20 7 65 74 Male 60 28 10 2 Female 47 33 18 2 All Male 68 14 12 6 Female 50 24 19 7 ALL 61 18 15 6 Nonpharm, nonpharmacological. * Hypertension defined as a mean systolic BP or a mean diastolic BP 140/90 mm Hg or currently treated with a prescription medication or Treatment type is reported. Rows may not add to 100% because of rounding. DISCUSSION This study presents, for the first time, data on hypertension awareness, treatment, and control status on a significant number of individuals representing the Canadian population. The standardized protocols used in these cross-sectional surveys are similar to those in the Third National Health and Nutrition Examination Survey (NHANES III), 7 and have the advantage of using four measurements for most of the participants. Using the mean values of all available measurements also reduces the likelihood of having a major bias in our estimates due to the white coat effect. In contrast to the NHANES III study, in which one set of BP measurements was taken by a physician, all of our measurements were taken by trained public health nurses, further reducing the likelihood of a significant white coat effect. There are some other differences between NHANES III and our study that are important to note for the comparisons that follow. First, our study stops at age 74 years, whereas NHANES III goes beyond 75 years. Our study spans a slightly longer time period, from 1986 to 1992. If any secular trend is affecting our data, however, it is toward 1992, when the most populated area in Canada (Ontario) was surveyed. Two sets of three BP measurements were taken in NHANES III, whereas we had two sets of two BP measurements. NHANES III excludes as hypertensives those individuals who have lowered their BP to 140/90 mm Hg with a nonpharmacological intervention, whereas we have included these individuals as controlled hypertensives. We have also included nonpharmacological treatment in the treated category, which slightly increases our treated and not controlled group by 2% if we handle this group in the same way as NHANES III (separate analysis). We will mainly limit our comparison to this US survey, as its

AJH OCTOBER 1997 VOL. 10, NO. 10, PART 1 HYPERTENSION CONTROL IN CANADA 1101 TABLE 7. PERCENTAGE DISTRIBUTION OF PERSONS BY SYSTOLIC AND DIASTOLIC BLOOD PRESSURE (BP), AGE, AND SEX AMONG TREATED AND NOT CONTROLLED HYPERTENSIVES* BP Categories (years) Sex N Systolic BP Diastolic BP <140 140 144 145 149 150 <90 90 94 95 99 100 18 34 Male 43 57 9 19 14 12 56 21 10 Female 20 70 12 5 13 4 76 15 5 35 64 Male 268 14 15 8 64 24 27 30 20 Female 260 10 14 20 56 41 37 14 8 65 74 Male 353 4 10 17 69 64 16 13 7 Female 511 2 15 10 73 71 15 7 6 All Male 664 13 13 11 63 34 25 25 16 Female 791 7 14 15 63 54 28 11 7 Total 1455 10 14 13 63 45 26 18 11 * Hypertension defined as a mean systolic BP or a mean diastolic BP 140/90 mm Hg or currently treated with a prescription medication or Rows may not add to 100% because of rounding. methodology more closely compares with our survey than do other international surveys. Compared with the NHANES III study, prevalence of hypertension was lower in Canadian women than in US women (18% v 22%), but was identical in Canadian and US men (26%). This difference in women may be due to the inclusion in NHANES III of older women ( 75 years), who are more likely than men to have survived and who also have higher blood pressure than do younger women. Our proportion of aware hypertensives (58%) was much lower than in the US study (69%), which suggests that (if it is not a reporting problem) a great number of persons in Canada with a BP 140/90 mm Hg have not been told that they have high BP. If, among the 39% (16% and 23%) of treated hypertensives, we look at the proportion (16/39; 41%) treated and controlled, this is lower but is not far from the 45% reported by NHANES III. Even if we include nonpharmacological treatment in the treatment group, we still have a much lower proportion of treated hypertensives than in NHANES III (39% v 53%). Other studies report lower hypertension prevalence rates using the same cutoff points of 140/90 mm Hg and similar or wider age groups. In China, Tao et al 8 found a prevalence of hypertension of 13.6% in the population aged 15 years and over, but a low level of awareness and control. The Hispanic Health and Nutrition Examination survey 9 of 1982 to 1984 found also a low prevalence of hypertension (16.8% of men and 14.1% of women) in Mexican-Americans and in Puerto Ricans in New York City (15.6% of men and 11.5% of women). Cuban-Americans in Florida had a higher hypertension prevalence (22.8% of men and 15.5% of women). In a rural population of Buenos Aires aged 15 to 75 years, De Lena et al 10 found a high prevalence of 39.8%, with a 47% awareness and a low 13% on medication in this aware group. In the Egyptian National Hypertension Project, Ibrahim et al 11 found among the population aged 25 and over a 26.3% hypertension prevalence, with a low level of awareness, medication treatment, and control (37.5%, 23.9%, and 8%, respectively). The major changes from the initial report on nine of the 10 Canadian provinces 4 was the use of 140 mm Hg and 90 mm Hg for the definition of hypertension instead of a diastolic BP 90 mm Hg alone, which was the standard cut-off point to define hypertension as advocated by past Canadian guidelines. This has resulted in the relative increase in the proportion of unaware hypertensives from 26% in the previous study to 42% in this study. Similarly, the proportion, among all hypertensives, of treated and controlled hypertensives has dropped from 42% in the previous study to 16% in this study. This difference may be due to the large emphasis in the past in using a diastolic BP of 90 mm Hg in Canada as a marker for hypertension, and as a cut-off point for treatment and for defining control, which may explain some of the differences that we have noticed, as mentioned above, with the US data. The data in Table 7 seem to support this hypothesis. Among the hypertensives treated and not controlled, 45% had a diastolic BP 90 mm Hg, with 26% in the 90 to 94 mm Hg range, whereas only 10% had a systolic BP 140 mm Hg, with 14% in the 140 to 145 mm Hg range. Another interesting finding, as shown in this table, is the age gender difference, in which women in the younger age groups tended to have lower BP than did men (although, in the 18 to 34 year old group, results are given for reference only, as numbers are small). If we translate prevalence and proportion figures into estimated population affected, we have about 4.1 million people aged 18 to 74 years in Canada who had

1102 JOFFRES ET AL AJH OCTOBER 1997 VOL. 10, NO. 10, PART 1 hypertension and who were at increased risk for coronary heart disease and stroke. Of these, about 960,000 were treated and not controlled; 757,000 were not treated and not controlled; and 1.7 million were not aware of their high BP. Most of these individuals with hypertension are not from the older age group. Separate analysis shows that only 27% were in the 65 to 74 years age group, whereas 61% were in the middle age group, with a nonnegligible proportion (12%) being in the 18 to 34 year age group. Even though prevalence of hypertension increases dramatically with age, it is important to realize that the burden of hypertension is occurring in the middle age group. In terms of prevention, it is also important to note that about 254,000 Canadian men (64%) aged 18 to 34 years are not aware of their hypertension, compared with only 15,000 Canadian women (19%), and this is not only due to a lack of screening, as Tables 1 and 2 show. In the older age group, in which hypertension is still expressing its risk, women are bearing the burden of hypertension (618,000, or 36% of all hypertensive women), compared with men (471,000, or 20% of all hypertensive men), and a greater number of women are treated and not controlled compared with men. Nevertheless, if we recalculate among the treated hypertensives the proportion who are not controlled, the proportion is the same (41%) in both sexes. Despite a Canadian health care system that is mostly free and provides relatively easy access, and in which a great proportion of the population have had their blood pressure measured in the last year, the prevalence of hypertension is still high, with a low level of control, mainly in the young male population. A major preventive effort that has started with the Canadian Heart Health Initiative needs to continue in the area of primary prevention to reduce hypertension risk factors in all ages but mainly in young adult males. Secondary prevention needs to emphasize better control in the management of hypertension, and the importance of nonpharmacological management, with or without medications, needs to be reinforced. A special effort needs to be made in the prevention and management of hypertension in elderly women. ACKNOWLEDGMENT We wish to acknowledge the other members of the Canadian Heart Health Surveys Research Group: Christofer Balram, PhD, Department of Health and Community Services, Fredericton, New Brunswick; Lynne Blair, BScN, MPA, British Columbia Ministry of Health, Victoria, British Columbia; David Butler-Jones, MD, MHSc, Saskatchewan Health, Regina, Saskatchewan; Roy Cameron, PhD, University of Waterloo, Waterloo, Ontario; Ruth Collins-Nakai, MD, University of Alberta, Edmonton, Alberta; Philip W. Connelly, PhD, St. Michael s Hospital and University of Toronto, Toronto, Ontario; Catherine Donovan, MD, MHSc, Memorial University of Newfoundland, St. John s, Newfoundland; Ron Dyck, PhD, Alberta Health, Edmonton, Alberta; Alison C. Edwards, MSc, Memorial University of Newfoundland, St. John s, Newfoundland; Dale Gelskey, MPH, DPH, University of Manitoba, Winnipeg, Manitoba; Kevin Hogan, MD, Memorial University of Newfoundland, St. John s, Newfoundland; Richard Lessard, MD, MPH, Public Health Directorate, Montréal, Québec; Sharon M. Macdonald, MD, University of Manitoba, Winnipeg, Manitoba; David R. Mac- Lean, MD, MHSc, Dalhousie University, Halifax, Nova Scotia; Ella MacLeod, RN, MSc, Prince Edward Island Heart Health Program, Charlottetown, Prince Edward Island; Mukund Nargundkar, MSc, MEng, Statistics Canada, Ottawa, Ontario; Brian A. O Connor, MD, MHSc, University of British Columbia, Vancouver, British Columbia; Gilles Paradis, MD, MSc, McGill University, Montréal, Québec; Bruce A. 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