Factors associated with hypertension awareness, treatment ... - Nature

Journal of Human Hypertension (2006) 20, 874–881 & 2006 Nature Publishing Group All rights reserved 0950-9240/06 $30.00 www.nature.com/jhh

ORIGINAL ARTICLE

Factors associated with hypertension awareness, treatment and control among ethnic groups in Amsterdam, The Netherlands: The SUNSET study C Agyemang1, I van Valkengoed1, R Koopmans2,3 and K Stronks1 1

Department of Social Medicine, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands; 2Department of Internal Medicine, Academic Medical Centre, Amsterdam, The Netherlands and 3Department of Pharmacology & Pharmacotherapy, Academic Medical Centre, Amsterdam, The Netherlands

We sought to determine factors associated with hypertension awareness, pharmacological treatment and control among ethnic groups in Amsterdam, The Netherlands. We analysed data on hypertensive subjects (Dutch n ¼ 130, Hindustani n ¼ 115 and African Surinamese n ¼ 225). After adjustments for important covariates, hypertension awareness was more common in Dutch people with abdominal obesity and family history of hypertension (FHH). Abdominal obesity was also associated with higher level of awareness in African Surinamese. Female sex, FHH and recent physician (general practitioner (GP)) visit were associated with higher level of awareness in both African and Hindustani Surinamese. Among the Dutch, hypertension treatment was more common in those with abdominal obesity, FHH and GP visit. Among Hindustanis, female sex, abdominal obesity and GP visit were positively associated with treatment of hypertension. Old age, female sex, FHH and GP visit were positively associated, whereas smoking was negatively associated with lower

treatment in African Surinamese. High education and more physical activity were associated with better blood pressure (BP) control, whereas obesity was associated with poor BP control among the Dutch. Among African Surinamese, female sex and FHH were associated with better BP control, whereas abdominal obesity was associated with poor BP control. Only old age was associated with poor BP control in Hindustanis. In conclusion, our findings indicate that more attention is needed in promoting awareness and treatment among those with lower hypertension risk (i.e., normal body weight people and those without FHH), those without recent GP visits in all ethnic groups and African and Hindustani Surinamese men and smokers. More effort is also needed in hypertension control among Dutch people with low education, obesity and inadequate physical activity, African Surinamese men and those without FHH and old Hindustani people. Journal of Human Hypertension (2006) 20, 874–881. doi:10.1038/sj.jhh.1002073; published online 24 August 2006

Keywords: hypertension awareness; treatment; control; ethnicity; The Netherlands

Introduction Hypertension is a powerful risk factor for cardiovascular morbidity and mortality. The risk of cardiovascular disease associated with hypertension is consistent and independent of other risk factors.1,2 The Global Burden of Hypertension data showed that more than a quarter of the world’s adult population had hypertension in 2000 and this is projected to increase by about 60% (1.56 billion) in 2025.3 The emerging data also suggest that the prevalence of Correspondence: Dr C Agyemang, Department of Social Medicine, Academic Medical Centre, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. E-mail: [email protected] Received 26 March 2006; revised 19 June 2006; accepted 19 June 2006; published online 24 August 2006

hypertension is even higher among some minority ethnic groups in Europe,4–9 particularly among African descent populations.5–9 The higher levels of cardiovascular disease morbidity and mortality among these ethnic groups is well reflected in the higher prevalence of hypertension.10,11 The lower levels of hypertension control reported in some African descent populations may, in part, explain their higher rates of cardiovascular disease morbidity and mortality.9 Uncontrolled hypertension is a serious risk factor for cardiovascular events such as stroke, heart failure, myocardial infarction and targetorgan damage. Studies have consistently shown that strict blood pressure (BP) control significantly reduces the occurrence of these cardiovascular outcomes. For example, by achieving the target of 140 mm Hg, there would be an estimated reduction

Factors associated with hypertension C Agyemang et al 875

of 28–44% in stroke and 20–35% in ischaemic heart disease depending on age.12 Determining factors associated with hypertension awareness, treatment and control is therefore critically important as a scientific basis for developing strategies to prevent the increasing burden of morbidity and mortality from hypertension-related cardiovascular diseases and complications.13 Evidence indicates that factors such as sex, geographical setting and body size are associated with hypertension awareness, treatment and control.13–16 However, it is unclear whether these factors are applicable in all ethnic groups in different social settings. The benefit of identifying these factors will be especially great among those ethnic groups with a disproportionately high prevalence of hypertension. However, data on these factors are limited, especially among minority ethnic groups in Europe. The main objective of this paper was to determine factors associated with hypertension awareness, pharmacological treatment and control among three ethnic groups in Amsterdam, The Netherlands.

Data and methods Study population

Data were obtained from the SUNSET study (acronym for: Surinamese in the Netherlands: Study on Ethnicity and Health). Details of the study methods have been published elsewhere.9 In short, the SUNSET study was a cross-sectional study that aimed to assess the cardiovascular risk profile among three ethnic groups in the Netherlands: Creole, Hindustani and White Dutch people. It was based on a random sample of 35- to 60-year-old, non-institutionalized people in South Amsterdam, The Netherlands. A random sample of Surinamese and White Dutch were drawn from the Amsterdam population register. Between 2001 and 2003, people in these samples were approached for an oral interview. The interviewers were matched by ethnicity and sex. The overall response rate was 60% among the Surinamese and 60% among White Dutch. Those who responded to the oral interview were invited for medical examination. The subsequent response rate was 84% among the Surinamese and 90% among the Dutch. The response rates were higher in women than in men in each ethnic group, but there were no differences between the ethnic groups in both men and women. The analyses that are presented here are based on the population that participated in the interview as well as the medical examination. The Medical Ethical Committee of the Amsterdam Academic Medical Centre approved the study protocols. All participants provided a written inform consent.

Measurements

Information on a wide variety of socio-demographics and medical history such as age, sex,

ethnicity, educational level, physical activity, history of smoking, alcohol consumption, hypertension, antihypertensive medication use, family history of hypertension (FHH), general practitioner (GP) visit over the last 2 months was obtained during the participant’s interview. Subjects were classified as Surinamese if they were born in Surinam, or had both parents born in Surinam. Approximately 80% of the Surinamese immigrants in the Netherlands are either Creole or Hindustani. Surinam was a former Dutch colony. In 1975, during the process of decolonization, almost half of the entire Surinam population (both Creole Surinamese and Hindustani Surinamese) migrated to the Netherlands. Surinamese people in the Netherlands are generally better integrated into the Dutch society than other ethnic minority groups due, in part, to their colonial links with the Dutch society. In the Netherlands, the term Creole is used to refer to the minority ethnic group with African ancestral origins (including mixed African and European descent) that migrated to the Netherlands via Surinam. For ease of international comparison, we refer to this group here as African Surinamese.17 The term Hindustani is used to refer to people with South Asian ancestral origin, and their offspring who migrated to the Netherlands via Surinam. The term Dutch refers to people with Dutch European ancestral origin. The ethnic groups were classified according to the self-reported ethnic origin of the respondent and/or the ethnic origin of the mother. Grandparents’ ancestry was used if this information was missing or unclear. Educational level was classified into two categories: low (secondary school and below) and high (vocational training and above). Alcohol consumption was classified into two categories: none or modest versus moderate or excessive. Physical activity was classified into two categories: X5 days, 30 min/day versus o5 days, 30 min/day. Height was measured without shoes with a measuring tape to the nearest 0.1 cm. Weight was measured in light clothing to the nearest 0.2 kg. Body mass index (BMI) was calculated as weight (kg) divided by height (m2). Overweight was defined as a BMI X25 kg/m2 (X23 kg/m2 for Hindustani group) and obesity was defined as BMI X30 kg/m2. Waist circumference was measured at midway between the lower rib margin and the iliac crest. Abdominal obesity was defined as waist circumference X102 and X88 cm for men and women, respectively. Hypercholesterolaemia was defined as total cholesterol X6.5 mmol/l. BP was measured in the morning with a validated oscillometric automated digital BP device (OMRON M-4 device) by specially trained physicians in the Amsterdam Academic Medical Centre. Using appropriate cuff sizes, two readings were taken on the right arm in a seated position after the subject had emptied their bladder and had been seated for at least 5 min. The mean of the two readings was used in the analyses. Journal of Human Hypertension


Hypertension was defined as a systolic blood pressure (SBP) X140 mm Hg, or diastolic blood pressure (DBP) X90 mm Hg, or being on antihypertensive therapy. Awareness of hypertension was defined as self-reporting of any prior diagnosis of hypertension by a health-care professional. Treatment of hypertension was defined as the proportion of hypertensives who were receiving prescribed antihypertensive medication for management of high BP at the time of the interview. Control of hypertension was defined as the proportion of patients on antihypertensive therapy with SBP o140 mm Hg and DBP o90 mm Hg. Data analysis

w2 Tests were used to test for evidence of differences in various proportions. Multiple logistic regression analyses were performed separately for each group to explore the associations between participants’ characteristics and hypertension awareness, treatment and control adjusting for age and sex. All statistical tests were two-tailed and P-values p0.05 were considered statistically significant. All statistical analyses were performed using SPSS for windows (SPSS Inc., Chicago, IL, USA).

Results

moderate to excessive alcohol consumption and hypercholesterolaemia were lower in both African Surinamese and Hindustani Surinamese than in Dutch people. Table 2 shows prevalence and age- and sexadjusted odds ratios of hypertension awareness, treatment and control between the ethnic groups. There were no significant differences in hypertension awareness between the Dutch and the Surinamese groups. However, Hindustani hypertensives were significantly more likely than the Dutch hypertensives to be treated for hypertension. African Surinamese hypertensives were significantly less likely than Dutch hypertensives to have their BP adequately controlled below BP o140/90 mm Hg. SBP control (SBP o140 mm Hg) did not differ but DBP control (DBP o90 mm Hg) was significantly lower in African Surinamese hypertensives than in Dutch hypertensives. Awareness, pharmacological treatment and control of hypertension

Table 3 shows the prevalence and Table 4 shows ageand sex-adjusted odds ratios (95% CI) of hypertension awareness, treatment and control by the study characteristics in each ethnic group. Awareness of hypertension

Table 1 shows the characteristics of the hypertensive subjects by ethnic group. Compared with Dutch hypertensives, African Surinamese and Hindustani Surinamese hypertensives were younger, less likely to be married and to be physically active. African Surinamese and Hindustani Surinamese hypertensives were less likely than Dutch people to be highly educated, but were more likely than Dutch people to be women, obese, have a FHH and have more frequent GP visits. The prevalence of smoking,

Among the Dutch hypertensives, abdominal obesity and FHH were associated with higher levels of hypertension awareness. These differences persisted after adjustment for age and sex in the logistic regression models. Female sex, abdominal obesity, FHH and a GP visit were associated with higher levels of hypertension awareness in both African Surinamese and Hindustani Surinamese hypertensives. Except for abdominal obesity in Hindustani people, these differences persisted after adjustment

Table 1 Characteristics of the hypertensive subjects by ethnic group

Age (mean; s.d.) Sex: Female (%) Married (%) High education level (%) Body size: Normal body weight (%) Overweight (%) Obesity (%) Abdominal obesity (%) Current smoker (%) Moderate – excessive alcohol intake (%) Physical activity: X5 days, 30 min/day (%) FFH (%) GP visit (%) Hypercholesterolaemia (%)

White Dutch (n ¼ 130)

Hindustani (n ¼ 115)

African Surinamese (n ¼ 225)

P-value

51.0 (6.8) 32.3 54.6 55.4

47.9 (5.9) 53.9 43.5 20.9

46.3 (5.9) 63.1 23.2 45.5

o0.001 o0.001 o0.001 o0.001

31.5 43.2 25.4 46.2

8.7 53.9 37.4 59.1

18.8 37.2 43.9 60.3

0.027

48.5 61.5 61.7 68.2 40.8 29.2

28.7 14.8 51.4 80.9 68.7 13.9

38.1 15.1 44.3 80.0 68.0 12.0

0.006 o0.001 0.008 0.02 0.001 0.001

o0.001

Abbreviations: FHH, Family history of hypertension; s.d., standard deviation. Journal of Human Hypertension


Table 2 Prevalence and sex- and age-adjusted odds ratios (95% CI) of hypertension awareness, treatment and control by ethnicity White Dutch (n ¼ 130)

Awareness among hypertensives Treatment among hypertensives Control among treated Control: SBP o140 mm Hg Control: DBP o90mm Hg


%

OR (95% CI)

%

49.6 23.1 46.7 53.3 63.3

1.00 1.00 1.00 1.00 1.00

60.0 47.8 38.9 46.3 55.6

OR (95% CI) 1.38 2.77 0.51 0.59 0.58

(0.82, (1.57, (0.19. (0.23, (0.22,

2.36) 4.90)*** 1.34) 1.51) 1.50)

African Surinamese (n ¼ 225) % 59.4 33.8 36.8 46.1 38.2

OR (95% CI) 1.29 1.51 0.38 0.50 0.25

(0.80, (0.89, (0.14, (0.19, (0.09,

2.09) 2.60) 0.99)* 1.26) 0.66)**

Abbreviations: CI, confidence intervals; DBP, diastolic blood pressure; OR, odds ratios; SBP, systolic blood pressure. *Po0.05, **Po0.01, ***Po0.001, comparing Afro-Surinamese and Hindustani Surinamese with the Dutch.

for age and sex. Obesity was also associated with hypertension awareness among African Surinamese, but the difference was no longer statistically significant after age and sex had been controlled for. Pharmacological treatment of hypertension

Obesity, FHH and GP visit were positively associated with pharmacological treatment of hypertension in Dutch hypertensives. Except for obesity, all the differences remained statistically significant after age and sex had been controlled for. In both African Surinamese and Hindustani Surinamese, female sex, abdominal obesity and a GP visit were positively associated with pharmacological treatment, whereas current smoking was negatively associated with pharmacological treatment. These differences still remained significant after adjustment for age and sex, except for abdominal obesity difference in African Surinamese and current smoking difference in Hindustani people. FHH and old age were also associated with high levels of treatment of hypertension among the African Surinamese people. Control of hypertension

Overweight, obesity and abdominal obesity were associated with poor BP control, whereas high education and physical activity were associated with better BP control among the Dutch hypertensives, the differences still remaining after controlling for age and sex, except for overweight. Among African Surinamese, female sex and FHH were associated with better BP control, whereas obesity and abdominal obesity were associated with poor BP control even after controlling for age and sex, except for obesity. Only old age was associated with poor BP control among the Hindustani Surinamese.

Discussion Promotion of awareness and management of patients with hypertension has had a positive impact on cardiovascular disease prevention in many countries,5,18,19 especially in North America, where the effort has been greatest.5 However, in

some ethnic groups in Europe, BP control is still far from optimal. For example, in our recent report, prevalence of hypertension was higher in African Surinamese men,9 but control was nowhere near the rule of halves.20 The control rate in African Surinamese men was far less than the control rate reported for their African American counterparts in the USA.18,21 The limited data on factors associated with hypertension awareness and management in ethnic minority groups in Europe may contribute, in part, to the lower control rate reported among this group. This present study extends our understanding and provides important findings on factors associated with awareness, treatment and control of hypertension among the Dutch ethnic groups in Amsterdam, The Netherlands. We found that old age was associated with pharmacological treatment in African Surinamese, but this did not translate into better BP control. Old Hindustani hypertensives also had poor BP control. This finding is consistent with Hyman and colleagues’ report in the USA,21 but contrasts Chen et al.’s22 report in Scotland where poor control was associated with young age. Our findings also show that male sex was associated with lower levels of awareness and pharmacological treatment of hypertension in both African Surinamese and Hindustani hypertensives. In addition, African Surinamese hypertensive men had poor BP control. Lower levels of hypertension awareness, treatment and control have been reported among men in several studies.15,21,22 However, with concerted efforts, better BP control could be achievable for men, especially African Surinamese men in Amsterdam. In NHANES III (1988–1994), for example, awareness and control rates among hypertensive subjects were significantly higher in women compared with men even after age and other demographic characteristics had been adjusted for.21 However, in the 1999–2000 NHANES, there was no significant difference between men and women as a result of significant increases in treatment and control rates in men.18 Our findings also show that obesity and abdominal obesity were associated with higher levels of awareness and pharmacological treatment but lower levels of BP control in African Surinamese and Dutch hypertensive subjects. These findings are Journal of Human Hypertension


Table 3 Prevalence (%) of hypertension awareness, treatment and control by socio-demographics and those with and without risk factors in each ethnic group Awareness of hypertension

Dutch Hindustani (n ¼ 130) (n ¼ 115)


Pharmacological treatment of hypertension Dutch (n ¼ 130)



Hypertension control

Dutch (n ¼ 30)

Hindustani African (n ¼ 54) Surinamese (n ¼ 76)

Age group 35–45 X46

50.0 49.5

53.8 63.2

59.2 59.5

23.1 23.1

35.9 52.6

33.3 34.1

50.0 45.8

64.3 30.0*

48.5 27.9

Sex Female Men

54.8 47.1

72.6 45.3**

66.9 46.3**

26.2 21.6

59.7 32.1**

38.7 25.3*

54.4 42.1

40.5 35.3

45.5 14.3**

Marital status Married No

47.1 52.5

58.0 61.5

49.0 62.2

21.1 25.4

52.0 43.1

25.0 36.0

40.0 53.3

30.8 46.4

23.1 38.7

Education level Low 52.3 High 37.8

61.9 44.4

61.1 51.2

32.8 15.3*

49.5 44.4

33.5 31.7

31.6 77.8*

39.5 25.0

37.3 30.8

Body size Normal Overweight Obesity

40.0 56.5 69.8

47.6 56.1 66.3*

19.5 17.9 36.4*

20.0 41.9 60.5*

26.2 30.1 38.0

85.7 40.0* 25.0*

50.0 46.2 30.8

54.5 48.0 26.3*

46.9 69.1*

44.9 68.7***

14.3 33.3

27.7 60.3***

23.6 40.0**

80.0 30.0**

38.5 39.0

47.6 33.3*

64.6

61.0

26.9

54.5

39.4

55.6

37.8

40.7

48.5

57.1

19.0

27.3**

23.8**

33.3

44.4

25.0

42.0

59.2

59.5

28.0

48.0

34.6

38.8

34.0

39.4

54.4

64.7

58.8

20.0

41.2

29.4

38.5

71.4

20.0

63.0

61.5

28.6

46.3

37.6

21.4

36.0

40.9

57.9

55.4

20.3

47.4

25.8

68.8**

37.0

29.2

45.0 42.9 66.7

Abdominal obesity No 40.6 Yes 60.0* Smoking status No 45.5 smoking Current 54.0 smoker Alcohol None or minor Moderate – excessive

Physical activity o5days, 53.1 30 min/day X5days, 47.4 30 min/day FHH No Yes

31.7 57.5**

36.4 65.6**

33.3 65.9***

7.3 29.5**

31.8 50.5

13.3 38.9***

33.3 46.2

42.9 38.3

0.0 42.0*

GP visit No Yes

43.4 58.5

36.1 70.9***

41.7 67.8***

13.0 37.7**

25.0 57.0***

8.3 45.8***

40.0 50.0

44.4 37.8

50.0 35.7

60.6 56.3

59.9 55.6

23.9 21.1

48.5 37.5

33.8 33.3

45.5 50.0

35.4 66.7

34.3 55.6

Hypercholesterolaemia No 57.7 Yes 42.1

Abbreviations: FHH, Family history of hypertension; GP, general practioner. *Po0.05, **Po0.01, ***Po0.001, comparing within ethnic group.

consistent with other reports,16,22 but contrast with that of He et al.’s14 study, in which higher control rates were found among overweight and obese Journal of Human Hypertension

African Americans and White people in the US. It has been suggested that overweight and obesity positively influence BP checking and prescription of

Table 4 Prevalence (%) and age- and sex-adjusted OR and (95% CI) of factors associated with hypertension awareness, treatment and control in South Amsterdam, the Netherlands

— 0.33 (0.05, 2.21) 2.98 (0.91, 13.88) 0.71 (0.14, 3.75) 0.73 (0.16, 3.33) 5.33 (0.80, 35.68) 2.13 (0.15, 30.20) 1.85 (0.32, 10.72) 1.08 (0.19, 6.02) 3.40 (1.66, 6.99)*** 2.68 (1.48, 4.86)*** 0.83 (0.36, 1.90)

5.74 (1.49, 19.48)** 2.12 (0.73, 6.14) 4.09 (1.71, 9.76)** 3.05 (1.21, 7.67)* 0.87 (0.35, 2.20) 0.70 (0.21, 2.34) 2.94 (1.30, 6.65)** 3.28 (1.16, 9.30)* 1.86 (0.91, 3.82) 3.34 (1.39, 8.03)** 0.67 (0.31, 1.45) 1.01 (0.31, 3.27)

1.30 (0.58, 2.94)

3.75 (1.48, 9.52)** 8.98 (3.64, 22.13)*** 0.98 (0.41, 2.32)

0.59 (0.20, 1.78) 12.99 (1.83, 92.28)** 0.96 (0.29, 3.24) 0.64 (0.28, 1.47)

0.62 (0.34, 1.14) 063 (0.49, 1.52) 0.96 (0.43, 2.19) 0.81 (0.39, 1.66)

OR (95%CI)

1.30) 18.95)* 6.28) 2.41) 3.42) 1.16) 0.85)* 2.09) 3.45) (0.18, (1.23, (0.33, (0.16, (0.16, (0.06, (0.05, (0.19, (0.11, 0.48 4.82 1.43 0.62 0.74 0.25 0.21 0.62 0.61 0.88)* 4.04) 6.97) 5.02) 10.23) 5.61) 0.6.02) 8.84) 34.32) (0.07, (0.35, (0.55, (0.04, (0.03, (0.02, (0.23, (0.38, (0.92, 0.24 1.18 1.96 0.42 0.54 0.29 1.19 1.84 5.62 4.40) 9.65) 7.62) 59.35)* 1.22) 0.70)* 0.71)* 1.78) 4.59) (0.89, (0.41, (0.25, (1.13, (0.01, (0.01, (0.01, (0.07, (0.21, 0.63 2.01 1.38 8.15 0.10 0.06 0.10 0.36 0.98 (1.03 3.42)* (1.02, 3.40)* (0.74, 3.17) (0.42, 1.81) (0.53, 2.85) (0.71, 3.70) (0.95, 3.83) (0.28, 0.99)* (0.42, 2.21) 1.87 1.86 1.53 0.86 1.23 1.63 1.90 0.53 0.96 4.57) 7.02)** 1.13) 3.12) 12.85) 21.77) 7.39)* 1.01) 3.09) (0.88, (1.45, (0.20, (0.17, (0.43, (0.64, (1.07, (0.15, (0.33, 1.99 3.19 0.47 0.72 2.35 3.74 2.80 0.39 1.00 2.76) 3.03) 2.84) 2.78) 2.51) 6.72) 7.24)** 1.51) 1.42) (0.36, (0.55, (0.54, (0.45, (0.32, (0.82, (1.26, (0.28, (0.26, 1.00 1.28 1.24 1.11 0.89 2.85 3.01 0.65 0.61 (0.43, 3.02) (1.34, 4.11)** (0.78, 2.94) (0.29, 1.19) (0.67, 3.05) (0.86, 3.98) (1.12, 4.16)* (0.59, 1.93) (035, 1.66) 1.14 2.35 1.52 0.58 1.43 1.85 2.16 1.07 0.76 1.96) 7.08)** 2.08) 1.82) 6.33) 9.02) 3.74) 1.76) 1.76) (0.12, (1.46, (0.39, (0.09, (0.36, (0.42, (0.55, (0.29, (0.17,

OR (95% CI) OR (95% CI) OR (95% CI)

0.48 3.21 0.90 0.41 1.52 1.95 1.44 0.72 0.56 2.53) 2.86) 2.46) 1.26) 2.04) 6.41) 4.35)* 2.94) 1.30) (0.15, (0.65, (0.61, (0.26, (0.39, (0.94, (1.03, (0.72, (0.31, 0.60 1.36 1.23 0.57 0.90 2.45 2.12 1.46 0.63

X45 years Female Not married High education Overweight Obesity Abdominal obesity Current smoker Moderate – excess alcohol PA: X5days, 30 min/day FHH: yes GP visit: yes Hypercholesterolaemia


African surinamese (n ¼ 76) OR (95%CI) Dutch (n ¼ 30) African Surinamese (n ¼ 75) OR (95% CI) Hindustani (n ¼ 115) OR (95% CI) Dutch (n ¼ 130) African Surinamese (n ¼ 225) OR (95% CI) Hindustani (n ¼ 115) OR (95% CI) Dutch (n ¼ 130)

Hypertension control Pharmacological treatment of hypertension Awareness of hypertension

Abbreviations: CI, confidence intervals; FHH, Family history of hypertension; GP, general practitioner; OR, ¼ odds ratios; PA, physical activity; pw ¼ per week. *Po0.05, **Po0.01, ***Po0.001, comparing within ethnic group.

Factors associated with hypertension C Agyemang et al

medication for intervention; hence, higher awareness and treatment levels.22 The contrasting results between our study and that of He et al.’s study may reflect differences in aggressiveness in treatment of hypertension between these two countries.9 The hypertension awareness, treatment and control rates in our present study9 are far lower than the rates reported in the USA.23 This clearly indicates that there is room for improvement in the ethnic groups studied here. The associations between socio-economic status and hypertension awareness, treatment and control have remained inconsistent. Previous reports had shown that education, for example, is the best socioeconomic predictor of awareness and control of hypertension.24,25 In Nieto et al.’s24 study, lower education level was associated with poor BP control. Other studies have, however, shown no such associations.14–16,22,23 On the contrary, others have found lower control rates among those with higher education levels.22 In the present study, we found no associations between education level and hypertension awareness and treatment in none of the ethnic groups considered here. The White Dutch hypertensives with high education were, however, more likely than those with lower education levels to have their BP adequately controlled. Several studies have found physical activity to be associated with improvements in BP control.14,15 In He et al.’s14 study for example, self-reported physical activity was associated with better BP control in all ethnic groups in the USA. In this present study, physical activity was associated with better BP control only in the Dutch hypertensives. The reasons for this lack of association in African Surinamese and Hindustani Surinamese are unclear. However, it is possible that the intensity of physical activity among African Surinamese and Hindustani Surinamese hypertensive subjects was not enough to have any meaningful effect. Nevertheless, these findings deserve urgent attention. FHH is a well-established risk factor for hypertension.26 However, very little is known about the associations between FHH and awareness, treatment and control of hypertension especially among different ethnic groups. One study that had assessed FHH and BP control found no association.27 In this present study, however, we found that FHH was a strong predictor of hypertension awareness and treatment in the Dutch ethnic groups in Amsterdam. FHH was also associated with better BP control in African Surinamese subjects. These findings may imply that the presence of FHH may positively influence individuals to check their BP and seek medication intervention. It may also well be that physicians pay more attention to patients with a FHH, as they are at greater risk of cardiovascular disease. A study in the Netherlands found that most physicians were more aggressive in their hypertension management if FHH was present.28 This may be

879

Journal of Human Hypertension


reflected in the higher treatment and control rates found in this study. The lower treatment rates found among smokers may reflect the higher smoking cessation advice rates given to hypertensive smokers reported among the Dutch physicians in the aforementioned study. Physicians may encourage this lifestyle modification before they prescribe medication.28 The present study also indicates that a GP visit is positively associated with hypertension awareness and pharmacological treatment in all the three ethnic groups in Amsterdam. These findings may suggest that access to health care may be an important factor for initiating hypertension management. It may also well be a selection effect of patients to GP practices. For example, patients with severe hypertension are more likely than those without to visit their GP. The lack of difference in BP control between subjects who had visited their GP and those who had not is, however, in contrast with other reports.14,29 For example, in Shea et al.’s29 study, severe uncontrolled hypertension was found to be more common among patients who had no primary care physician. These findings may either reflect poor compliance with antihypertensive therapy or lack of aggressiveness in treatment of hypertension in the Netherlands.9,30

Limitations The study has some limitations. As in many surveys, our BP levels were based on the average of two measurements at a single visit, which might have overestimated the prevalence rates. The definition of BP control is also based on measurements at a single visit. The effect of differences in white-coat effect cannot be ruled out.31 The cross-sectional nature of our study design indicates that causal associations can only be made with caution. In addition, the response rates and sample sizes were relatively small resulting in a wide CI for some of the analyses. Other potential sources of bias may include the documentation of self-reported hypertensive treatment by the participants. For instance, participants who reported wrongly for not receiving antihypertensive therapy and had their BP below 140/90 mm Hg were classified as normotensives. Nevertheless, these limitations should not limit the comparability of the groups, as these limitations apply to all the groups studied. Finally, treatment rates were based on only pharmacological treatment of hypertension. More work is needed in assessing factors associated with non-pharmacological treatment of hypertension, including dietary habits and physical activity. In conclusion, our findings have important public health implications. First, more attention is needed in promoting hypertension awareness among those with lower hypertension risk (i.e., those with normal body sizes and those without FHH), and Journal of Human Hypertension

those without frequent GP visits in all ethnic groups, and African and Hindustani Surinamese men. Second, more attention is needed in improving pharmacological treatment among those with lower hypertension risk, those without frequent GP visits, African and Hindustani Surinamese smokers and men, and African Surinamese younger age group. Third, more effort is also needed in hypertension control among Dutch people with low education, obesity and inadequate physical activity; African Surinamese men and those without FHH; and old Hindustani people. Public health and clinic interventions to improve hypertension awareness, treatment and control will need to take these factors into account. Such measures will have an important effect in reducing hypertension-related complications in the Netherlands, especially among African Surinamese in whom prevalence of hypertension is highest.9

What is known on this topic K Hypertension is public health burden in Europe and the rates are high in older people of African descent. K Hypertension control is lower in African Surinamese than in White Dutch in the Netherlands. K Determining factors associated with hypertension management and control is crucial for prevention. What this paper adds High education and physical activity are associated with better, whereas obesity is associated with poor BP control in White Dutch. K Old age is associated with poor BP control in Hindustanis. K Female sex and FHH are associated with better, whereas abdominal obesity is associated with poor BP control in African Surinamese. K

Acknowledgements The Health Research and Development Council of the Netherlands (ZonMw) supported this project. We are grateful to Ank de Jonge, Msc Public Health (TNO Quality of Life, Leiden, the Netherlands) for her useful comments on the earlier draft.

References 1 Kearney PM, Whelton M, Reynolds K, Muntner P, Whelton PK, He J. Global burden of hypertension: analysis of worldwide data. Lancet 2005; 365(9455): 217–223. 2 Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA, Izzo Jr JL, et al., Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. National Heart, Lung, and Blood Institute; National High Blood Pressure Education Program Coordinating Committee. Seventh report of the Joint National Committee on Prevention, Detection,


3 4

5

6

7

8 9

10 11

12

13

14

15

16

17

Evaluation, and Treatment of High Blood Pressure. Hypertension 2003; 42: 1206–1252. Kearney PM, Whelton M, Reynolds K, Muntner P, Whelton PK, He J. Global burden of hypertension: analysis of worldwide data. Lancet 2005; 365: 217–223. Bindraban NR, Stronks K, Klazinga NS. Cardiovascular risk factors for Surinamese in the Netherlands: a literature review. Ned Tijdschr Geneeskd 2003; 147: 1591–1594. Agyemang C, Bhopal R, Bruijnzeels M, Redekop WK. Does nocturnal blood pressure fall in people of African and South Asian descent differ from that in European white populations? A systematic review and metaanalysis. J Hypertens 2005; 23: 913–920. Agyemang C, Bhopal R. Is the blood pressure of people from African origin adults in the UK higher or lower than that in European origin white people? A review of crosssectional data. J Hum Hypertens 2003; 17: 523–534. Agyemang C, Bhopal RS. Is the blood pressure of South Asian adults in the UK higher or lower than that in European white adults? A review of cross-sectional data. J Hum Hypertens 2002; 16: 739–751. Lane DA, Lip GY. Ethnic differences in hypertension and blood pressure control in the UK. Q J Med 2001; 94: 391–396. Agyemang C, Bindraban N, Mairuhu G, Montfrans G, Koopmans R, Stronks R. Prevalence, Awareness, Treatment, and Control of Hypertension among ethnic minority groups in Amsterdam, the Netherlands – The SUNSET study. J Hypertens 2005; 23: 1971–1977. Balarajan R. Ethnic differences in mortality from ischaemic heart disease and cerebrovascular disease in England and Wales. BMJ 1991; 302: 560–564. Bos V, Kunst AE, Keij-Deerenberg I, Garssen J, Mackenbach JP. Ethnic inequalities in age- and causespecific mortality in The Netherlands. Int J Epidemiol 2004; 33: 1112–1119. Whelton PK, He J, Appel LJ, Cutler JA, Havas S, Kotchen TA, et al., National High Blood Pressure Education Program Coordinating Committee. Primary prevention of hypertension: clinical and public health advisory from The National High Blood Pressure Education Program. JAMA 2002; 288: 1882–1888. Whelton PK, Beevers DG, Sonkodi S. Strategies for improvement of awareness, treatment and control of hypertension: results of a panel discussion. J Hum Hypertens 2004; 18: 563–565. He J, Muntner P, Chen J, Roccella EJ, Streiffer RH, Whelton PK. Factors associated with hypertension control in the general population of the United States. Arch Intern Med 2002; 162: 1051–1058. Muntner P, Gu D, Wu X, Duan X, Wenqi G, Whelton PK et al. Factors associated with hypertension awareness, treatment, and control in a representative sample of the Chinese population. Hypertension 2004; 43: 578–585. Agyemang C, Bruijnzeels MA, Owusu-Dabo E. Factors associated with hypertension awareness, treatment, and control in Ghana, West Africa. J Hum Hypertens 2006; 20: 67–71. Agyemang C, Bhopal R, Bruijnzeels M. Negro, Black, Black African, African Caribbean, African American or

18 19

20

21 22

23

24

25

26

27

28

29

30

31

what? Labelling African origin populations in the health arena in the 21st century. J Epidemiol Community Health 2005; 59: 1014–1018. Hajjar I, Kotchen TA. Trends in prevalence, awareness, treatment, and control of hypertension in the United States, 1988–2000. JAMA 2003; 290: 199–206. Primatesta P, Poulter N. Improvement in hypertension management in England: results from the Health Survey for England 2003. J Hypertens 2006; 24: 1193–1200. Marques-Vidal P, Tuomilehto J. Hypertension awareness, treatment and control in the community: is the ‘rule of halves’ still valid? J Hum Hypertens 1997; 11: 213–220. Hyman DJ, Pavlik VN. Characteristics of patients with uncontrolled hypertension in the United States. N Engl J Med 2001; 345: 479–486. Chen R, Tunstall-Pedoe H, Morrison C, Connaghan J, A’Brook R. Trends and social factors in blood pressure control in Scottish MONICA surveys 1986-1995: the rule of halves revisited. J Hum Hypertens 2003; 17: 751–759. Wang Y, Wang QJ. The prevalence of prehypertension and hypertension among US adults according to the new joint national committee guidelines: new challenges of the old problem. Arch Intern Med 2004; 164: 2126–2134. Nieto FJ, Alonso J, Chambless LE, Zhong M, Ceraso M, Romm FJ et al. Population awareness and control of hypertension and hypercholesterolemia. The Atherosclerosis Risk in Communities study. Arch Intern Med 1995; 155: 677–684. Lang T, Pariente P, Salem G, Tap D. Social, professional conditions and arterial hypertension: an epidemiological study in Dakar, Senegal. J Hypertens 1988; 6: 271–276. Stamler R, Stamler J, Riedlinger W, Algera G, Roberts R. Family (parental) history and prevalence of hypertension: results of a nationwide screening program. JAMA 1979; 241: 43–46. Degli Esposti E, Di Martino M, Sturani A, Russo P, Dradi C, Falcinelli S et al. Risk factors for uncontrolled hypertension in Italy. J Hum Hypertens 2004; 18: 207–213. Wassenberg MW, Willemsen JM, Gaillard CA, Braam B. Hypertension management in primary care: standard care and attitude towards a disease management model. Neth J Med 2004; 62: 375–382. Shea S, Misra D, Ehrlich MH, Field L, Francis CK. Predisposing factors for severe, uncontrolled hypertension in an inner-city minority population. N Engl J Med 1992; 327: 776–781. Schelleman H, Klungel OH, Kromhout D, de Boer A, Stricker BH, Verschuren WM. Prevalence and determinants of undertreatment of hypertension in the Netherlands. J Hum Hypertens 2004; 18: 317–324. Agyemang C, Raj Bhopal, Bruijnzeels M, Redekop KW. Does white-coat effect in people of African and South Asian descent differ from those of the European origin white people? A systematic review and meta-analysis. Blood Press Monit 2005; 10: 243–248.

Journal of Human Hypertension