Dr. Yoga NathanPublic Health

UL

160/95 mm Hg?

140/90 mm Hg?

160/95 mm Hg?

140/90 mm Hg?

How can we define `Hypertension’ or `High blood pressure’?

BY DEFINING THE BP LEVEL ABOVE WHICH ITIS BENEFICIAL TO REDUCE BP

This the definition generally used Arbitrary definition, changing over time

1950s DBP 120 1960s DBP 110 1980s DBP 100 SBP 160 Now DBP 90 SBP 140

A small proportion of individuals with high blood pressure have a specific medical cause (secondary hypertension):

<1% in general population<5% in medical clinics

The rest have no specific medical cause (primary or essential hypertension)

a) -Coarctation of aortab) -Renal and renal vascular diseasec) -Adrenal diseased) cortical 1 hyperaldosteronism,e) Cushing’s syndromef) medulla phaeochromocytomag) -Pregnancyh) -Drugs esp OCP, HRT

Rural communities in less developed settings

Hunter gatherer, subsistence diet low in fat, salt, alcohol Low mean body mass index High physical activity Low stress levels (?)

-Generally show that blood pressure patterns change (increase) to those of the host population:

* Change generally occurs within 6 months* Strong evidence for ENVIRONMENTAL

influence on population BP* May be exceptions – high BP in African-

Caribbeans may have genetic basis

SBP higher by:-

-High body mass index 15 mmHg -High alcohol intake 8 mmHg -High salt intake 5 mmHg -Low potassium intake 5 mmHg -Low fibre/high fat 2-3 mmHg -Physical inactivity 2-3 mmHg -Stress ????

Age being older Ethnicity African-Caribbean Family history positive Body mass Overweight/obese Alcohol intake high

Which is more strongly related to risk, systolic or diastolic?

-Both are important, systolic slightly more so

-In older people, `high’ systolic BP can occur with `normal’ diastolic pressure (isolated systolic hypertension), is associated with increased CV risk

How strong are the relative risks of high blood pressure (60-69 years)?

-Usual systolic BP 20 mmHg higher:- relative risk of stroke 2.32 relative risk of CHD 1.85

-Usual diastolic BP 10 mmHg higher:- relative risk of stroke 2.50 relative risk of CHD 1.79

Applies above SBP 115, DBP 75 mmHg

Prospective Studies Collaboration, Lancet 2002

0

5

10

15

20

25

80 100 120 140 160 180 200

Systolic Blood Pressure (mm Hg)

Per

cen

t o

f P

op

ula

tio

n

95th percentile

Source: NHANES II

90th percentile

0

2

4

6

8

10

12

<120 120-139 140-159 160-179 180+

Systolic Blood Pressure (mm Hg)

Str

oke

Rat

e p

er 1

,000

P

op

ula

tio

n

Source: Framingham Heart Study, 1980

(Adjusted for age, serum TC, current smoking status for each quartile)Van den Hoogen PCW, et al, for the Seven Countries Study Research Group. N Engl J Med. 2000;342:1-7.

140

Mor

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rom

CH

D(N

o./1

0,00

0 P

erso

n Y

ears

) 130120110100

9080706050403020100110 120 130 140 150 160 170

Systolic Blood Pressure (mm Hg)

United States

Northern Europe

Mediterranean southern Europe

Inland southern Europe

Serbia

Japan

Build/Bp Study: 1935-1954;Metropolitan Life

150/100

140/95

130/90

120/80

0 10 20 30 40 50

16 yr Lost

9 yrs

4

DIES

• Angina Angina pectorispectoris

• Unstable Unstable anginaangina

• Myocardial Myocardial infarctioninfarction

• Sudden deathSudden death• Heart failureHeart failure

• TIATIA• Ischemic Ischemic

strokestroke• Hemorrhagic Hemorrhagic

strokestroke

• Renovascular Renovascular diseasedisease

• Renal failureRenal failure

• ClaudicationClaudication• AneurysmAneurysm• Critical limb Critical limb

ischemiaischemia

Hypertension

-Coronary (ischaemic) heart disease -Stroke (all types) -Ischaemic stroke -Haemorrhagic stroke -Subarachnoid haemorrhage -Heart failure -Hypertensive heart disease -Sudden death -Renal failure -(All-cause mortality) How do we know this?

Population-Based Population-Based StrategyStrategy

Population-Based Population-Based StrategyStrategy

Hypertension 1991;17:I-16–I-20.Hypertension 1991;17:I-16–I-20.

Reduction in SBPmmHg

2

3

5

Reduction in SBPmmHg

2

3

5

% Reduction in Mortality % Reduction in Mortality

Reduction in

BP

Reduction in

BP

After Interventio

n

After Interventio

n

Before Intervention

Before Intervention

Stroke CHD Total

-6 -4 -3

-8 -5 -4

-14 -9 -7

SBP DistributionsSBP Distributions

SOURCES OF DIETARY SALT

6%

1% 3%

81%

9%

Processed Food

Water

Cooking Salt

Table SaltOtherSodium

Source: James et al. The dominance of salt in manufactured food in the sodium intake of affluent societies. Lancet 1987;8530:426-428.

Raised blood pressure is the biggest single cause of cardiovascular disease accounting for 62% of strokes and 49% of heart disease.

Strokes and coronary heart disease kill more people around the world than any other cause of death – around 12.7 million people each year.

It is estimated that reducing salt intake by 6g a day could lead to a 24% reduction in deaths from strokes and an 18% reduction in deaths from coronary heart disease, thus preventing approximately 2.6 million stroke and heart attack deaths each year worldwide.

Preventable

Treatable

Controllable

Why is so Difficult to Do?

Sustained reduction in blood pressure over about 5 years effectively reverses the risks of the higher pressure

-If usual diastolic BP 10 mmHg lower:- relative risk of stroke reduced by about 60% relative risk of CHD reduced by about 44%

Greater BP reduction gives greater CV risk reduction-Similar BP reduction (e.g. 10 mmHg) will reduce

relative risk of CVD by similar amount, whatever the starting blood pressure

Because the relations of BP and CVD risk are continuous there is no rational target for BP reduction (pragmatic targets for patients on treatment)

Br Hyp Soc SBP <140 DBP < 85 mmHg

Who should have their BP lowered?-The traditional view:The reason for lowering blood pressure is that it is high….`People who need their blood pressure lowered are those who have a high blood pressure’

-The new viewThe reason to lower blood pressure is to reduce the risk of cardiovascular disease`People who need their blood pressure lowered are those who are at high risk of cardiovascular disease (almost irrespective of their blood pressure)’

-The third (middle) way`Blood pressure should be treated on its merits but should take account of overall CV risk’

ModificationModificationApproximate SBP Approximate SBP

ReductionReduction(range)(range)

Weight ReductionWeight Reduction 5-10 mmHg/10kg5-10 mmHg/10kg

Adopt DASH eating planAdopt DASH eating plan 8-14 mmHg8-14 mmHg

Dietary sodium reductionDietary sodium reduction 2-8 mmHg2-8 mmHg

Physical activityPhysical activity 4-9 mmHg4-9 mmHg

Moderation of alcohol Moderation of alcohol consumptionconsumption

22––4 mmHg4 mmHg

Lifestyle ModificationsLifestyle ModificationsLifestyle ModificationsLifestyle Modifications

Self

Self

Other

Other

Responsibility for a Problem(Who is to blame?)

Responsibility for a Solution

(Who will control the future?)

Enlightenment Model• Person feels guilty• Person needs discipline

Compensatory Model• Person feels deprived• Person needs power

(skill)

Moral Model• Person feels lazy• Person needs motivation

Medical Model• Person feels ill• Person needs treatment

* Brickman, American Psychologist 37(4):368–384, April 1982.

Patient cooperates with doctor, and BP is controlled. Patient told, “It’s okay now.”

Drops out

Drops out

Patient stops medicine and visits.

Patient doesn’t understand the difference between control and cure. He thinks he’s “cured”.

Patient receives no re-education about the lifelong need for treatment.

Patient believes doctor meant “Stop taking the medicine” when he said, “You’re under control.”

Belief that he’s “cured” and “told to stop medicine” is reinforced.

Patient believes– His diagnosis – Hypertension is serious– In the efficacy of medicine– He can control HBP with

doctor’s help.

Patient doesn’t want to think of himself as “sick.”

Patient receives

no call from doctor.

Patient believes– His diagnosis– In medicine and its

efficacy to lower blood pressure

– In the need for lifelong treatment

– In the hazard of HBP if left uncontrolled

Patient believes hypertension is “nervous tension.”

Patient believes he can control HBP with “self-discipline” or by “accepting life.”

Patient feels no need to see doctor and keep appointments because he knows when to take medicine.

Drops out

Drops out

Medical system does not follow up to recall patient for appointments.

Patient has no symptoms to tell him that blood pressure is uncontrolled.

Patient believes medicine is needed only to lower blood pressure, not to keep it low.

Patient believes he can tell when BP is high since he knows when he is tense.

Patient takes medicine when he feels tense and believes this adequately lowers BP.

Patient believes he’s adequately controlled—reinforced by lack of professional intervention.

Remains Uncontrolled

• Public health approaches, (e.g. reducing Public health approaches, (e.g. reducing calories, saturated fat, and salt in processed calories, saturated fat, and salt in processed foods) can achieve a downward shift in a foods) can achieve a downward shift in a population’s BP. population’s BP.

• Reducing overall BP by only a few mm Hg Reducing overall BP by only a few mm Hg could affect overall CVD morbidity and could affect overall CVD morbidity and mortality by as much or more than treatment mortality by as much or more than treatment alone.alone.

• Public Health approaches provide an Public Health approaches provide an attractive opportunity to interrupt and attractive opportunity to interrupt and prevent the costly cycle of managing prevent the costly cycle of managing hypertension and its complications.hypertension and its complications.