EPIDEMIOLOGY OF HYPERTENSION (HT)

HYPERTENSION

• It is commonest CVD

• It is a major RF for CV mortality, CHD, CVA, CHF, and RF

• The relationship between BP and risk of CVD events is continuous, consistent, and independent of other RFs. The higher the BP the greater the chance of heart attack, HF, stroke, and kidney diseases.

• In EMR it affects about 25% of adult population

• About 75% of hypertensive individuals are unaware of being diseased

• About 50% of hypertensive patients who knew they are diseased are either not on treatment or taking treatment but not controlled.

HYPERTENSION

• Definition of hypertension is arbitrary

• BP follows normal distribution curve

• BP has a high intra-individual variation

• CV risk associated with HT is strongly correlated with both SBP and DBP, correlation is higher with SBP

Population with HT constituted a risk pyramid:

• No. of individuals with mild HT at the base of the pyramid is high, but the RR is small

• No. of individuals with sever HT at the tip of the pyramid is small, but the RR is high

• Absolute no. of complications attributable to HT is more at base than the tip of the pyramid

To achieve community control of HT related CV complications it is

important to control mild HT

• A 2mm decrease in the entire distribution will decrease mortality from stroke by 6%, CHD by 4% and all causes by 3%

• Beginning at 115/75mmHg, CVD risk (IHD and Stroke) doubles for each increment of 20/10mmHg

• BP values between 130-139/85-89mmHg are associated with a more than twofold increase in relative risk from CVD as compared with those with BP levels below 120/80 mmHg

• DHT predominates before age 50, either alone or in combination with SBP elevation

• The prevalence of SHT increases with age and above 50 SHT represents the most common form of HT

• DBP is a more potent CV RF than SBP until the age 50, thereafter SBP is more important.

CLASSIFICATION OF HT

The severity of HT depends on:

• BP level

• Concomitant CV RFs

• End-organ damage

For practical reasons, HT can be classified into

1.HT with NO other CV RFs and NO target organ damage

2.HT with other CV RFs

3.HT with evidence of target organ damage

4.HT with other CV RFs AND evidence of other organ damage

Classification of HT by BP level:

TYPE SBP (mmHg) DBP (mmHg)

• Normotensive <140 and <90• Mild HT 140-180 or 90-105• Subgroup, Borderline HT 140-160 or 90-95• Mod. And Severe HT >180 or >105• Isolated SHT >140 and <90

• Borderline SHT 140-160 and <90

Classification of HT by Target Organ Damage:

• Stage I: No Manifestation

• Stage II: At least one of the following:

1.LVH

2.Gen. or Focal narrowing of retinal arteries

3.Microalbuminuria; proteinuria: and /or slight increase in serum creatinin level (1.2-2 mg/dl)

4.U/S or radiology evidence of plaque in aorta, carotid, iliac, or femoral arteries

Stage III: Appearance of symptoms or signs

• Heart: AP MI HF• Brain: Stroke TIA HT encephalopathy Vascular dementia

• Optic fundi Retinal Hmg. And

exudates +/- papilloedema

• Kidney: S.creatinin level > 2 mg/dl RF• Vessels: Dissecting aneurysm Symptomatic occlusive

disease

Opti

c

fundi

Reti

nal

Hmg.

And

exudates

+/-

papill

oede

ma

Classification of HT by Causes

I.Primary (essential) HT

II.Secondary HT:

• Renal: renal parenchyma dis., Reno vascular dis. , rennin producing tumor

• Drugs: OC, Corticosteroids , Liquorices< carbenoxolone, sympathomometics , NSAIDs

• Endocrin:Acromegaly, Cushing Syndrome, Primary hyperaldosteronism, Congenital adrenal hyperplasia, Pheochromocytoma, Carcinoid tumors

• Coarctation of Aorta and Aoartitis• Pregnancy induced HT

RECLASSIFICATION OF BP

• New data of lifetime risk of HT and the increase of CV complications associated with levels of BP previously considered to be normal

• JNC 7 introduced “ prehypertension”• The aim is to identify those in whom early

intervention by adoption of healthy lifestyle could reduce BP, decrease the rate of progression of BP to hypertensive levels with age, or prevent hypertension entirely.

JNC6 categorySBP/DBPJNC7 category

Optimal>120/80Normal

Normal

Borderline

120-129/80-84

130-139/85-89

Prehypertension

Hypertension≥140/90Hypertension

Stage 1

Stage 2

Stage 3

140-159/90-99

160-179/100-109

≥180/110

Stage 1

Stage 2

Stage 2

CLASSIFICATION OF BP FOR ADULTS

BP classification

SBP

mmHg

DBP

mmHg

NORMAL>120And <80

PREHYPERTENSION

120-139Or 80-89

STAGE 1 HT140-159Or 90-99

STAGE 2 HT≥160Or ≥100

• Prehypertension is not a disease category. They are not intended to have drug therapy, but should be advised to practice lifestyle modification to reduce risk of developing HT

• Individuals with prehypertension who also have DM or kidney diseases should be considered candidates for appropriate drug therapy if a trial of lifestyle modification fails to reduce their BP to 130/80mmHg or less.

• This classification does not classify HT patients by the presence or absence of RFs or target organ damage in order to make different treatment recommendations, should either or both be present.

• All patients with stage 1 or 2 should be treated and the goal is to reduce BP in HT patients with no other compelling conditions <140/90

• The goal for individuals with prehypertension with no compelling conditions is to lower BP to normal levels with lifestyle changes, and prevent the progressive rise in BP using the recommended lifestyle modifications.

Factors influencing BP level:

– Age: appositive association between BP level and age in most populations of different geographical, cultural, and SE characteristics. The rise in SBP continue throughout life in contrast to DBP which rises until the age 50, tends to level off over the next decade, and may remain the same or fall later in life.

– Sex: early in life, there is no difference between males and females in BP level, but after puberty males tend to have higher BP level than females. After menopause the difference gets narrower.

Factors influencing BP level:

– Ethnicity: Blacks have higher BP level than others

– SE status: in post-transitional populations –inverse relation

In pre and transitional populations – positive association

Risk Factors of HT

1.Hereditary factors : positive family history

2.Genetic factors: certain genes as ACE gene

3.Early life exposure to certain events: as LBW

4.Certain childhood predictors: as BP response to exercise, weight gain, LV mass…

Risk Factors of HT

5.Body weight: overweight individual has 2-6 times higher risk having HT compared to a normal weight individual.

6.Central Obesity and Metabolic Syndrome: high waist/hip ratio is positively associated with HT

7.Nutritional factors: positive association between Nacl intake and HT, negative association between potassium intake and HT, and no relation with other nutrients.

Risk Factors of HT

8.Alcohol intake : causes acute and chronic increase in BP level

9.Physical Inactivity : Sedentary unfit individual has 20-50% excess risk to have HT

10.Heart rate : Ht patients have HR than normotensive individuals

11.Psychological factors: acute mental stress causes increase in BP level

12.Environmental factors: noise, air pollution

Organ Damage Associated With HT

• The incidence depends on level of other RFs as DM, HCH, Smoking…

1. LVH:

• Powerful predictor of CV complications

• Higher risk with strain pattern than with voltage pattern

• Best diagnosed by Echo.

• Reversible by anti-HT , and causes improvement of diastolic function with no impairment of systolic function

2.Atherosclerosis:

Higher in presence of other RFs

3.CHF :

• Progressive LV dilatation

• LVH+ Coronary Atherosclerosis mark the development of CHF

• Anti-HT can decrease incidence of CHF by 50%

4.Stroke :

• HT is the most important and the most modifiable Rf of all types of stroke

• 5-6 mmHg reduction in DBP can decrease incidence of stroke by 40%

5.Carotid Stenosis

• Frequent cause of stroke

• Ulcerated plaques can be a source of emboli causing TIA

6.Kidney:

• Severe accelerated HT causes fibrinoid necrosis of small blood vessels leading to renal insufficiency

• Renal damage in HT is heralded by proteinuria• Microalbuminurea and proteinurea are

• independent RF of all CV mortality

• Effective BP reduction can decrease risk of proteinurea

Prevention of HT

• Community Approach

Primary prevention of HT in the whole population

Prevention of HT

• High risk Approach ( individual case management)

Identification of individuals with high BP who are at increased of complications

The two approaches are complementary

Needs of HT control Strategy

1.Data collection: prevalence of HT, RFs of HT, and other CVDs

2.Early Detection: in the health setting and increased self referral through increased public awareness

3.Health Care Services: responding to the needs of HT patients, and providing adequate diagnostic and treatment facilities

Needs of HT control Strategy

4.Coordination of the government and NGOs concerned in primary prevention of HT and integrate it NCDs Prevention Program, concentrating on life style measures

5.Community Participation: health education

6.Medical Audit: to monitor the process and quality of care to patients with HT

Community ApproachAim: Primary Prevention of HT through:

1.Elimination of modifiable RFs

2.Promotion of protective factors maintaining reasonable BP

3.Reduction of risks of complications by altering the norms and behavior of population

It is useful to:

– Avoid risky life-style that increase BP

– Adoption of healthy life-style

– Encourage industrial and agricultural activities to provide healthier food

Goals :

• Increase population awareness that HT is a major PH problem

• Help in detection of HT patients or those at risk

• Advocate life –style that eliminate controllable RFs

Components :

1. Public Education:

• Nature, causes, complications, prevalence and treatable nature of HT.

• Life –style measures for prevention, management, and contributory role of other CV RFs.

Components :

2. Professional Education:

• Training in detection, management, and prevention of HT.

• Adoption of advocacy role in the community to adopt healthy life-style.

Components :

• 3. Patient Education:

Components:

• The need for effective management• Benefits of life-style changes • The need to adhere to health care advice • Regular monitoring and periodic visits

Population approach is highly effective in decreasing HT and its complications in the community,

but it offers little direct individual effect, making it of less motivation to people and physicians.

Life style modification at population level requires:

1.Inter-sectoral collaboration

2.Multidisciplinary approach

3.Community involvement and participation particularly through NGOs

Individual ApproachAim: Prevention of complications among HT

patients

Components:

• Identification of HT patients at risk of complications• Effective management of HT through life-style

modification with or without pharmacologic intervention.

This approach is associated with high motivation for patients and physicians, but it is costly.

The two approaches are complementary to each other

Lifestyle measures for prevention of HT

In the whole population (primary prevention) they help in:

• Decrease risk of development of HT

• Decrease risk of development of other life-style related disorders (DM, CHDs,)

Lifestyle measures for prevention of HT

In individual patient, they help in:

• Decrease BP

• Avoid or decrease need for anti-HT treatment

• Control associated RFs

FOYR life-style measures proved effective in clinical trials:

1.Weight Reduction

• Decreases BP in HT patients with >10% overweight

• Decreases insulin resistance

• Improves lipid profile

Obese patients with mild or borderline HT should try weight reduction for 3-6 months before starting anti-HT treatment

2.Reduction of alcohol intake:

• Decreases SBP/DBP by 4.8/3.3 mmHg

• When combined with 10 Kg weight loss , BP will decrease by 10.2/7.5 mmHg

3.Increased physical activity

• Effective for prevention and treatment of HT

• Dynamic , isotonic exercises ( walking) is more effective than static , isometric exercises ( weight lifting)

• Brisk walking for 30-60 minutes /day for 5 times / week is better than strenuous exercises.

4.Reduction of Sodium intake

• Recommended intake is < 6 gm /day

• Elderly people and blacks demonstrate more sensitivity to sodium restriction

Life style measures to control other CV RF

1.Tobacco smoking

• Smoker hypertensive has 2-3 folds excess risk of stroke and CHD.

• Cessation of smoking is the most effective single step to decrease CV risk among hypertensive.

Life style measures to control other CV RF

2.Dyslipidemia

Increased physical activity is most appropriate in HT patients with dyslipidemia

Life style measures to control other CV RF

3.Diabetes Mellitus

Regular exercise, weight reduction, and low fat high fiber diet can improve insulin sensitivity, and decrease contribution of insulin resistance to high BP.