Ethnic patterns in cardiovascular disease: findings from national surveys suggest change in risks across generations

Seeromanie Harding University of Glasgow

Heterogenous patterns of cardiovascular diseases among ethnic groups

• High rates of coronary heart disease (CHD) among South Asians but not Caribbeans

• High rates of hypertensive cardiovascular disease among Caribbeans

• The causes of ethnic differences in cardiovascular disease are unclear

• Very little known about when differences begin to emerge over the lifecourse

0 20 40 60 80 100

Stroke

0 50 100 150 200 250 300 350

Eng & Wales

India

Pakistan

Bangladesh

Caribbean

CHD

Death rates/100 000 by country of birth, E&W 1989-92

0

100

200

300

CHD Hypertension Stroke

400

0

100

200

300

400

CHD Hypertension Stroke

Blacks born in South

Blacks born in North East

Whites

Blacks born in Caribbean

/100 000 /100 000

Death rates by birthplace, New York 1988-92, 45-64 years

Men Women

Fang J, Madhavan S, Alderman H N Engl J Med 1996; 335:1552-1558

Cappucio F 2004;33:387-388 Gillum 1996; 335(21):1597-1599

Gillum’s stages in the epidemiological evolution of cardiovascular disease patterns among people

of sub-Saharan African origin

0

10

20

30

40

%

< 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 8.5

Fasting glucose mmol/l

Cameroon-rural 0.5 Cameroon-urban 1.4 Jamaica 3.0 Manchester 6.4

International Comparisons: Glucose tolerance distributions among west African-origin people

% diabetes (treated)

Mbanya JC, Cruickshank JK, Forrester T et al. Diabetes Care 1999;22:434-40

BMI >=25 kg/m2 for west African-origin populations

01020304050607080

Rural Urban Jamaica Manchester

MalesFemales

Cameroon

Mbanya JC, Cruickshank JK, Forrester T et al. Diabetes Care 1999;22:434-40

%

• These international & population studies suggest that environmental factors play the major role in explaining ethnic patterns in cardiovascular disease

• In the UK, large government surveys (prospective & cross-sectional) provide opportunities to track changes in risk

ONS Longitudinal Study (LS)

• ONS Longitudinal Study (LS) - 1% of population of England & Wales followed up 1971-2000

• Data from censuses & vital registrations linked to LS records

• Information on country of birth (names), year of arrival, date of birth and socio-economic circumstances in census

Example of LS records1971 Census

1991 Census

1981 Census end of follow-up

2000

deathArrived 1950 aged 40 years

Arrived 1960 aged 35 years

South Asians in the UK: Cardiovascular mortality, 1971-2000, & yearly change of residence

Age in1971

Hazardratio

95% CI Deaths

25-34 1.09~ 1.03-1.16 7335-44 1.04 1.00-1.09 10845-54 1.02 1.00-1.05 77

Harding. Epidemiology 2003;14(3):287-292

Adjusted for gender and age at start of study

~ p<0.05

South Asian v. all other LS members: Cardiovascular mortality by duration of residence

0.5

1.0

1.5

2.0

2.5

25-34 35-44 45-54

Age in 1971

Long stay (arrived before mean year of arrival for age group)

Short stay (arrived after mean year of arrival for age group)

Harding. Epidemiology 2003;14(3):287-292

Caribbeans in the UK: CHD/stroke mortality,1971-2000,& yearly change in residence

Age in1971

Hazardratio*

95% CI Deaths

CHD

35-44 0.93 0.69-1.25 2345-54 1.21 0.94-1.57 28

Stroke

35-44 1.37 0.95-1.99 1545-54 1.56~ 1.12-2.17 20

*Adjusted for age at migration & socio-economic circumstances

~ p<0.05

Harding. IJE 2004;33:382-386

Caribbeans in the UK: effect of age at migration & duration of residence, stroke mortality (45-54 years)

Hazardratio*

95% CI

Age atmigration 1.68~ 1.22-2.32

Duration ofresidence 1.56~ 1.12-2.17

*adjusted for socio-economic circumstances~p<0.05

Harding. IJE 2004;33:382-386

Using the HSE’99 to track risk across generations

• Metabolic profiles of UK-born Black Caribbeans do not appear to be as protective against CHD as those of foreign-born Black Caribbeans

Abbots, Harding, Cruickshank Atherosclerosis 2004;175:295-303

UK-born Black Caribbeans: Cardiovascular risk profiles, 35-44 years

27.6*27.7BMI (kg/m2)

5.35.6Glycosylated Hb (%)

5.06.0Fasting glucose (mmol/l)

0.9*1.5Triglycerides (mmol/l)

1.541.32*HDL (mmol/l)

72 76dBP (mmHg)

121132sBP (mmHg)

Black C’bean women (N=135)

Black C’bean men (N=75)

•p<0.05 compared with general population

• Abbots, Harding, Cruickshank Atherosclerosis 2004;175:295-303

UK-born Black Caribbeans/Irish: Triglycerides x BMI, 35-44 years

Abbots, Harding, Cruickshank Atherosclerosis 2004;175:295-303

womenmen

UK-born Black Caribbeans: Smoking prevalence among, 35-44 years

0

10

20

30

40

50

Men Women

%

Black Caribbean

General Population

Abbots, Harding, Cruickshank Atherosclerosis 2004;175:295-303

HSE’99 sample - difficulty in tracking risk across generations & across age

Ethnicgroup

35-44 45-54 55-64 65-74 75+

C’bbeanForeign-bornUK-born

108203

98 6

184 0

140 1

42 1

IndianForeign-bornUK-born

278 22

212 3

0120

1181

132

PakistaniForeign-bornUK-born

235 8

150 1

90 1

33 0

5 0

I rishForeign-bornUK-born

41229

45174

50 77

50 62

37 33

• Biological programming - link between poor early development and adult cardiovascular disease (Barker 1995)

• Social programming – link between childhood disadvantage and adult health (lifecourse framework)

• In the UK, we know very little about the relationship between birthweight & growth in childhood, & how this influences cardiovascular risk among ethnic groups

School children in Jamaica: Foetal growth & cardiovascular risk

Birth weight (g) Mean systolic BP

<=2500 105.4

2501-2750 105.4

2751-3000 103.6

3001-3250 100.9

3251-3500 102.2

3501-3750 102.2

>3750 101.8

Forrester T, Wilks RJ, Bennet FI et al BMJ 1996; 312:156-60

Birthweight distributions by ethnicity of mother

African origin

0

10

20

30

40

50

1000- 1500- 2000- 2500- 3000- 3500- 4000->=4500g

WhiteUK-born Black CaribbeanForeign-born Black Caribbean

%

0

10

20

30

40

50

1000- 1500- 2000- 2500- 3000- 3500- 4000->=4500g

White

UK-born Black African

Foreign-born Black African

%

Harding S, Rosato M, Cruickshank JK. IJE 2004;33:1-7

0

10

20

30

40

50

1000-1500-2000-2500-3000-3500-4000->=4500g

WhiteUK-born IndianForeign-born Indian

%

0

10

20

30

40

50

1000-1500-2000-2500-3000-3500-4000->=4500g

WhiteUK-born PakistaniForeign-born Pakistani

0

10

20

30

40

50

1000-1500-2000-2500-3000-3500-4000->=4500g

WhiteUK-born BangladeshiForeign-born Bangladeshi

Birthweight distributions by ethnicity of mother

South Asian origin

Harding S, Rosato M, Cruickshank JK. IJE 2004;33:1-7

Intergenerational non-genetic transmission of risk

• Growth and social conditions in early life and childhood

• Health in adolescence and adulthood

• Social, behavioural, psychosocial influences over the life course

• Historical processes e.g. slavery & post-emancipation poverty

BUT• Need for larger sample sizes of ethnic minorities to

increase power of the studies • Need for prospective data on ethnic minorities to

track social, metabolic, anthropometric risks over the lifecourse & over generations

• Need for comprehensive coverage of ethnic minorities

• Need for recording of ethnicity on death certificates & for improving its recording on inpatient records

Government surveys remain the most valuable source for examining the epidemiology of cardiovascular disease among ethnic minorities