EPIDEMIOLOGY OF HYPERTENSION (HT)

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EPIDEMIOLOGY OF HYPERTENSION (HT)
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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.

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• 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.

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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

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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

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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

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• 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

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• 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.

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CLASSIFICATION OF HT

• The severity of HT depends on
• BP level
• Concomitant CV RFs
• End-organ damage

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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

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Classification of HT by BP levelTYPE
SBP (mmHg) DBP (mmHg)

• Normotensive
  lt140 and lt90
• Mild HT
  140-180 or 90-105
• Subgroup, Borderline HT 140-160
  or 90-95
• Mod. And Severe HT gt180
  or gt105
• Isolated SHT
  gt140 and lt90
• Borderline SHT
  140-160 and lt90

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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

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Stage III Appearance of symptoms or signs
Optic fundi Retinal Hmg. And exudates
/- papilloedema

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

• Optic fundi
• Retinal Hmg. And exudates /- papilloedema
• Kidney
• S.creatinin level gt 2 mg/dl
• RF
• Vessels
• Dissecting aneurysm
• Symptomatic occlusive disease

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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 , Liquoriceslt
  carbenoxolone, sympathomometics , NSAIDs
• EndocrinAcromegaly, Cushing Syndrome, Primary
  hyperaldosteronism, Congenital adrenal
  hyperplasia, Pheochromocytoma, Carcinoid tumors
• Coarctation of Aorta and Aoartitis
• Pregnancy induced HT

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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.

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JNC7 category SBP/DBP JNC6 category

Normal lt120/80 Optimal
Prehypertension 120-129/80-84 130-139/85-89 Normal Borderline
Hypertension 140/90 Hypertension
Stage 1 Stage 2 Stage 2 140-159/90-99 160-179/100-109 180/110 Stage 1 Stage 2 Stage 3
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CLASSIFICATION OF BP FOR ADULTS
DBP mmHg SBP mmHg BP classification
And lt80 lt120 NORMAL
Or 80-89 120-139 PREHYPERTENSION
Or 90-99 140-159 STAGE 1 HT
Or 100 160 STAGE 2 HT
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• 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.

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• 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 lt140/90

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• 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.

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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.

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• 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.

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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

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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

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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.

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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

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Organ Damage Associated With HT

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

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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

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2.Atherosclerosis

• Higher in presence of other RFs

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3.CHF

• Progressive LV dilatation
• LVH Coronary Atherosclerosis mark the
  development of CHF
• Anti-HT can decrease incidence of CHF by 50

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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

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5.Carotid Stenosis

• Frequent cause of stroke
• Ulcerated plaques can be a source of emboli
  causing TIA

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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

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Prevention of HT

• Community Approach
• Primary prevention of HT in the whole population

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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

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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

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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

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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

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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

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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

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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.

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Components

• 2. Professional Education
• Training in detection, management, and prevention
  of HT.
• Adoption of advocacy role in the community to
  adopt healthy life-style.

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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

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• 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.

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• Life style modification at population level
  requires
• 1.Inter-sectoral collaboration
• 2.Multidisciplinary approach
• 3.Community involvement and participation
  particularly through NGOs

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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

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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,)

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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

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• FOYR life-style measures proved effective in
  clinical trials

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1.Weight Reduction

• Decreases BP in HT patients with gt10 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

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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

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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.

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4.Reduction of Sodium intake

• Recommended intake is lt 6 gm /day
• Elderly people and blacks demonstrate more
  sensitivity to sodium restriction

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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.

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Life style measures to control other CV RF

• 2.Dyslipidemia
• Increased physical activity is most
  appropriate in HT patients with dyslipidemia

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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.