CLIN. AND EXPER. HYPERTENSION, 18(3&4), 387-397 (1996)

CONTROL OF HYPERTENSION IN THE POPULATION. STRATEGIES IN AFFLUENT AND DEVELOPING COUNTRIES

I. Gyarfas Cardiovascular Diseases World Health Organization

Geneva, Switzerland

Keywords: Hypertension control, Population strategy.

ABSTRACT

Control of hypertension in population. Strategies in affluent and developing countries.

The control of hypertension encompasses primary prevention, early detection and adequate treatment of high blood pressure.

Primary prevention involves action at the population level to reduce obesity, alcohol and salt consumption, and to increase physical activity. diagnostic work-up, assessment of overall cardiovascular disease risk, non-pharmacological and pharmacological treatment.

The management of hypertension involves

The majority of community control programmes emphasized detection and treatment, rather than primary prevention. There are limitations to pharmacological treatment of hypertension, as shown by various studies, where a significant proportion of hypertensives have not been controlled by the treatment applied. In addition, the blood pressure-cardiovascular risk relationship is continuous and progressive and, even within the conventionally defined Ionormotensive” range, complications occur which escape control.

387

Copyright 0 1996 by Marcel Dekker, Inc.

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388 GYARFAS

Developing countries will encounter the problem of prohibitive costs of care and drug treatment for hypertension. Therefore greater emphasis must be put on primary prevention in population control of hypertension.

INTRODUCTION

Control of hypertension is a complex, multidimensional

process. The objectives of the control of hypertension consist

of primary prevention, early detection and adequate treatment to

prevent the complications of hypertension. These objectives

need implementation both at population level through lifestyle

changes using intersectorial collaboration, multidisciplinary

approaches with community involvement and participation, as well

as at a high level with diagnostic work, nonpharmacological and

pharmacological treatment of hypertensive individuals. The

attainment of these objectives also calls for action beyond the

healthcare system on a more general, societal level.

RESULTS

The WHO project assessed the control of hypertension in

communities in several centres in different parts of the world,

including developed and developing countries. In the

intervention communities after five years the proportion of

lower blood pressure classes, particularly those below 130 mmHg

systolic and 80 mmHg diastolic, had increased, i.e. those in the

higher class decreased. In the reference communities slight

changes occurred in the opposite direction. Changes in the mean

blood pressure to a certain extent reflect those in the

distribution. In the hypertensive subjects the changes were

approximately twice as large. It is noteworthy that in the

reference areas there were substantial decreases in diastolic

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CONTROL OF HYPERTENSION

F I G . 1 Differences in awareness rates between terminal and baseline surveys in the intervention and reference communities in four countries

blood pressure in all subgroups, while the systolic blood

pressure fell less, and only in women.

389

Figure 1 shows that the awareness rate increased to a

greater extent in the intervention than in the reference

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GYARFAS

community in North Karelia and Padua. The treatment rate was

considerably higher than in the reference population.

In the developing countries, in Mongolia and in Cuba, the

patterns in awareness and treatment rates did not follow the

observed changes of industrialized countries. While in Finland

and Italy the rates of awareness and treatment increased to a

greater extent in the intervention communities, in Ulan Bator

and in Havana such changes could not be observed (1). The

National Heart, Lung, and Blood Institute (NHLBI) launched the

NHBPEP. A mass media programme increased public awareness of

the decrease and it alerted the public to the benefits of having

blood pressure measured. Table 1 shows the result of the

national campaign: more Americans became aware of hypertension

and the treatment and control rates increased remarkably after

two decades of work.

The WHO MONICA Project’s objective is to monitor trends

and determinants of cardiovascular diseases. Blood pressure

values are being carefully measured at subsequent surveys, and

individuals have been asked whether they have been taking

antihypertensive medications. The prevalence of hypertension in

the majority of centres is over 20%, and that is so for all

centres from Eastern Europe and Yugoslavia. Out of the 35

MONICA centres, the prevalence of hypertension is over 30% in 12

centres in males, and in 10 centres in females. Females are

treated and controlled more frequently than males. In the

majority of centres the treatment rates did not reach 50% of the

hypertensives. In 5 centres with males, and in 16 centres with

females, the treatment rate exceeded 50%. The blood pressure

was controlled (i.e. blood pressure lower than 160/95 mmHg) in

only 15% of the hypertensive populations in 20 centres with

males and 8 centres with females (2).

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TABL

E 1

Hype

rtens

ion

Awar

enes

s, Tr

eatm

ent,

ani

Cont

rol R

atts

Cale

gory

19

71-1

972t

197

4-19

75t

1976

-198

0# 1

988-

1991

s

Awar

e: o/o

of

pers

ons w

ith h

yper

tens

ion t

old

by p

hysic

ian

51

64

(54)

73

(65)

84

Trea

ted:

Yo o

f per

sons

with

hyp

erte

nsio

n tak

ing m

edica

tion

36

34

(33)

56

(49)

73

Cont

rolle

d: %

of p

erso

ns w

ith h

yper

tens

ion w

ith b

lood

pres

sure

<1

60/9

5 m

mHg

on

one

occa

sion a

nd re

porte

d cur

rent

ly ta

king

antih

yper

tens

ive m

edica

tion

16

20

(11)

34

(21)

55

Defin

ed a

s 16

0195

mm

Hg o

r m

ore

on o

ne o

ccas

ion

or r

epor

ted

curre

ntly

takin

g an

tihyp

erte

nsive

med

icatio

n.

t Sou

rce:

Nat

ional

Healt

h and

Nut

ritio

n Ex

amina

tion S

urve

y 1.

4 So

urce

: Nat

ional

Healt

h and

Nut

ritio

n Ex

amina

tion S

urve

y II.

5 So

urce

: Nat

ional

Healt

h and

Nut

ritio

n Exa

mina

tion S

urve

y 111 (

unpu

blish

ed da

ta pr

ovid

ed by

the C

enter

s for

Dise

ase C

ontro

l

Num

bers

in pa

rent

hese

s are

per

cent

ages

at 1

40/9

0 m

mHg

or m

ore.

and

Prev

entio

n, N

atio

nal C

enter

for H

ealth

Sta

tistic

s).

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FIG. 2 Differences in treatment rates between terminal and baseline surveys in the intervention and reference communities in four countries

The ARIC Study (The Atherosclerosis Risk in Communities

Study) has identified levels of awareness, treatment and control

of hypertension and hypercholesterolaemia in population samples

in four U . S . communities. About 84% of hypertensive subjects

were aware of their condition, and about 50% had it treated and

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CONTROL OF HYPERTENSION 393

controlled. Hypertension was more prevalent in blacks, and

awareness was higher in women and blacks, whereas hypertensive

blacks were less likely to be treated once aware and

particularly less likely to have their hypertension controlled

once treated ( 3 ) .

The percentages of hypertensive subjects aware of their

condition and treated with medication have increased

dramatically during the past 20 years. At the same time,

mortality rates from coronary heart disease and stroke have

declined dramatically, which may result at least in part from

increased diagnosis and treatment of hypertension.

There are limitations to pharmacological treatment of

hypertension. Recent survey data from the WHO MONICA Project,

ARIC Study and NHANES I11 indicate that about half of

hypertensive individuals have reduced their blood pressure

adequately. The remainder are unaware of their hypertension,

not receiving treatment or inadequately treated.

Furthermore, because treatment does not cure but only

controls hypertension, therapy is usually lifelong: costs and

long-term adverse effects of treatment may become substantial.

This is even more relevant for patients with mild hypertension.

In addition, the blood pressure-cardiovascular risk

relationship is continuous and progressive. Complications occur

even within the conventionally defined llnormotensivell range.

It is clear from this MRFIT screening follow-up data that,

even under optimal conditions, the treatment and control of

hypertension will influence no more than 70% of the blood

pressure related CHD excess deaths in the community (14).

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THE

Baseline SBP and CHD

HBP-CHD R I S K PYRAMID

death races fo r m e n screened in MRFIT A DEATHS

A 7 . 2 2

a 2.7%

pzziq 23 .42 I HBP

8

\ I I 1-1 \, I . 3% ,I

28.42

19.0%

FIG. 3 Source: Adapted from: Stamler J, Stamler R, Neaton JD. Blood pressure, systolic and diastolic, and cardiovascular risks: US population data. Archives of Internal Medicine, 1993, 153:598-615.

The primary prevention of hypertension - the prevention of elevation of blood pressure - is principally linked to lifestyle

modifications addressed to the total population. Such lifestyle

changes could include weight loss, decreased alcohol

consumption, sodium reduction and increased physical activity.

Randomized trials in normotensive subjects have achieved 1-2

mmHg reductions in DBP. The application of an intervention

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CONTROL OF HYPERTENSION 395

strategy uniformly to a population would shift the blood

pressure distribution downward. The effect of a 2 mmHg shift in

DBP would reduce coronary heart disease incidence by 9% and that

of stroke by 15% (5).

DISCUSSION

The prevention of complications resulting from high blood

pressure in any population requires:

1) reducing the risk of developing high blood pressure in the

population as a whole (population approach);

2 ) the identification of individuals with high blood pressure

who are at an increased risk of complications.

From the perspective of developing countries, the

prevention of hypertension is a great imperative. These are

societies in epidemiologic transition, with deleterious

lifestyle changes accompanying economic development. Major

epidemics of cardiovascular disease have been projected to occur

or are already occurring in these countries. Campaigns for mass

screening, case detection and long-term pharmacotherapy will

face barriers of prohibitive cost, an overburdened health

infrastructure and socioeconomic constraints. Especially since

these countries are at present coping with a double burden of

persistent problems of infectious and parasitic diseases,

malnutrition, and AIDS, together with cardiovascular disease and

cancer.

Hence, the containment of an established epidemic of high

blood pressure faces great obstacles. The fact that the

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distribution of blood pressure in many developing countries is

to the left (downward) of those in industrialized countries, the

right shift should be prevented, rather than achieving a left

shift in the latter.

Every country, industrialized or developing, should

develop its own programme according to local needs and

resources. The main objectives of a national hypertension

control programme are the prevention of high blood pressure

through the adoption of appropriate behaviour patterns in the

entire population, as well as the prevention of complications of

hypertension through adequate measures for identification and

management of hypertensive persons within the community.

Wherever possible, this programme should be established within

the broader context of a comprehensive cardiovascular disease

programme or as part of integrated noncommunicable disease

control programme.

REFERENCES

1. Ambrosio GB, Strasser T, Dowd JE, Tuomilehto J, Nissinen A , Froment A, Milon H, Miguel JMP, Macias Castro I, Dondog N, Zamboni S, Dal Palu C. Effects of interventions on community awareness and treatment of hypertension: result of a WHO study. Bulletin of the World Health Organization. 1988; 66(1) : 107-113.

2. The WHO MONICA Project. Geographical variation in the major risk factors of coronary heart disease in men and women 35-64 years. World Health Statistics Quarterly. 1988; 41 (3/4) : 115-140.

3. Nieto JF, Alonso J, Chambless LE, Zhong Ming, Ceraso M, Romm FJ, Cooper L, Folsom AR, Saklo M. Population awareness and control of hypertension and hypercholesterolaemia. Arch. Intern. Med. 1995; 155: 677-684.

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CONTROL OF HYPERTENSION

4. Stamler J, Stamler R , Neaton JD. Blood pressure systolic and diastolic and cardiovascular risks: US population data. Arch. Intern. Med. 1993;153: 598-615.

5. Cook NR, Cohen J, Herbert PR, Taylor JO, Hennekens CH Implications of small reductions in diastolic blood pressure for primary prevention. Arch. Intern. Med. 1995, 155: 701-709.

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