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Epidemiology and treatment of hypertension

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Title: Randomised Controlled Trials Author: Ashnita Bali Last modified by: SACTRC Created Date: 7/4/1996 3:19:46 PM Document presentation format: 35mm Slides – PowerPoint PPT presentation

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Title: Epidemiology and treatment of hypertension


1
Epidemiology and treatment of hypertension
  • Note the first part of this presentation on
    risk-based assessment of BP treatment has been
    provided by Professor Rod Jackson, Head of
    Division of Community Health
  • Faculty of Medical Health Sciences
  • University of Auckland

2
Part 1
  • Defining hypertension and making decisions
    based on cardiovascular risk

3
Argument
  • 1. There is no clinically relevant entity that
    can be defined by a mildly raised blood pressure.
  • 2. A mildly raised blood pressure level is not
    a major determinant of which patients benefit
    from blood pressure lowering

4
  • what is mild hypertension?

5
Systolic blood pressure distribution Framingham
Study participants 35-64 years
top x??
74-119 120-139 140-159 160-179 180-300
SBP (mmHg)
6
??
7
??
32
30
28
26
18
17
16
16
11
10
8
(No Transcript)
9
Definitions of mild hypertension prevalence
10
Definitions of mild hypertension prevalence
?? 130/80
11
  • what is mild hypertension?
  • its the wrong question

12
  • who benefits from blood pressure lowering?

13
Meta-analysis of RCTs of BP lowering drugs
15,559 patients, SBP diff 17 mmHg, DBPdiff 9
mmHg, follow-up 4.1 years ( 60 years)
Endpoint Odds ratio (Relative risk red.)
Stroke mortality 36
Stroke morbidity 35
CHD mortality 25
CHD morbidity 15
0 0.5 1.0 1.5
Insua et al Ann Intern Med 1994121355-62
14
Stroke and blood pressure loweringsubgroup
analysis from 17 RCTs
Trial Events
Relative risk red. group
control treatment
All entry 2.2 1.3
39 DBP lt 110
Some 110, 6.5 4.6 32
all 115
Some or all 8.2 4.7 45
115
0 0.5 1.0 1.5
MacMahon Rogers J Vasc Med Biol 19934265-71
15
Stroke and blood pressure loweringsubgroup
analysis from 17 RCTs
Trial Events Odds
ratio (Relative risk red.) group
control treatment
Younger 2.3 1.3 43
patients
Older 7.0 4.6 34
patients
1º prev. 3.2 2.0 38
2º prev. 27.3 18.8 38

0 0.5 1.0 1.5
MacMahon Rogers J Vasc Med Biol 19934265-71
16
Stroke and blood pressure loweringsubgroup
analysis from 17 RCTs
Trial Events Odds
ratio (Relative risk red.) group
control treatment
Younger 2.3 1.3 43
patients
1
Older 7.0 4.6 34
patients
2.4
1º prev. 3.2 2.0 38
1.2
2º prev. 27.3 18.8 38

8.5
0 0.5 1.0 1.5
MacMahon Rogers J Vasc Med Biol 19934265-71
17
  • which patients should be treated?
  • individual treatment can only be justified if
    there is individual benefit
  • only absolute benefits are relevant to patients

18
(45 prospective studies 450,000 people 13,000
events)
PSC Lancet 19953461647-53
19
PSC Lancet 19953461647-53
20
Absolute risk of CVD risk in 40 year old men by
SBP and other risk factors, Framingham, USA
700
CVD risk per 1000 in 8 years
459
326
210
46
SBP 105 ----189 105 ----189 105 ----189
105 ----189 105 ----189 high chol. -
gluc intol.
- -
cigarettes - - -
LVH - - -
-
21
WOMEN
Diabet
es
No
D
iabet
es
Ratio of Total CholesterolHDL
Ratio of Total CholesterolHDL
AGE
70
AGE
60
AGE
50
AGE
40
Ratio of Total CholesterolHDL
Ratio of Total CholesterolHDL
22
Diabetes
No
Diabetes
Ratio of Total CholesterolHDL
Ratio of Total CholesterolHDL
AGE
70
23
CVD risk NNTs
5yr CVD risk 5 yr NNT gt 30 lt 10 . 5-10
40 2.5-5 85 lt 2.5 gt120 assumes 33
RRR
24
is BP lowering therapy indicated ?
60 yr old man BP 148/ 88 mmHg smoker TC 240
mg/dl HDLC 38 mg/dl BMI 25 no Hx CVD
50 yr old woman BP 160/95 mmHg non smoker TC 240
mg/dl HDLC 62 mg/dl BMI 25 no Hx CVD
25
is BP lowering therapy indicated ?
60 yr old man BP 148/ 88 mmHg smoker TC 240
mg/dl HDLC 38 mg/dl
50 yr old woman BP 160/95 mmHg non smoker TC 240
mg/dl HDLC 62 mg/dl
5 yr absolute CVD risk 24 5 yr NNT 12
5 yr absolute CVD risk 4 5 yr NNT 72
26
50/60 yr old woman non smoker TC 240 mmol/L HDLC
60 mmol/L No diabetes
SBP mmHg 150 160 170 5 yr NNT 90 / 50 70 /
42 60 / 37
27
To treat or not to treat mild hypertension
  • treat risk not blood pressure
  • only absolute risks and benefits are relevant to
    patients
  • the payer should choose the threshold

28
Part 2Pharmacological considerations in
hypertension management
  • Sue Hill and David Henry
  • Discipline of Clinical Pharmacology

29
Factors that influence blood pressure
  • sympathetic nervous system
  • total peripheral resistance
  • mainly arterioles
  • intravascular volume (renin-angiotensin)
  • renal excretion
  • atheroma, thrombosis

30
things that alter vascular resistance
  • vascular smooth muscle
  • mediators from sympathetic nerves and vascular
    endothelium
  • calcium dependent
  • contraction due to ? intracellular calcium
  • relaxation due to ? calcium entry or ?cGMP, cAMP
  • depends on intact endothelium
  • complex, interdependent biochemical reactions

31
drugs that will reduce vascular resistance
  • nitric oxide, nitrates
  • ?- antagonists
  • ?- antagonists
  • Calcium channel blockers
  • angiotensin II antagonsists
  • (lots more)

32
other mechanisms to remember
  • central control -
  • methyldopa, ganglion blocking drugs
  • renal excretion of sodium and water
  • diuretics, spironolactone

33
drugs we use for hypertension
  • ?- blockers
  • thiazide diuretics
  • Calcium channel blockers
  • angiotensin converting enzyme inhibitors
  • ( others - alphamethyldopa, reserpine,
    hydralazine, prazosin )

34
thiazide diuretics
  • ACTION
  • increase sodium and water excretion by decreasing
    reabsorption of sodium and chloride in the distal
    tubule (later effect on vessels)
  • EFFECT
  • lowers blood pressure- over several days
  • decreases complications, morbidity and mortality
    ( good clinical trials)
  • Side effects
  • metabolic effects diabetes, gout, low Na, K,
    impotence

35
?- adrenoceptor antagonists
  • ACTION
  • effects on heart (?1) and smooth muscle (?2 ) via
    noradrenaline
  • lowers BP
  • reduces cardiac output
  • reduces renin release
  • reduces central sympathetic activity
  • effect on pre-synaptic noradrenaline release
  • nonselective antagonist propranolol
  • relatively selective ?1 metoprolol, atenolol
  • mixed agonist/antagonist - oxprenolol

36
?- adrenoceptor antagonists
  • EFFECT
  • lowers blood pressure - over several days
  • decreases complications, mortality and morbidity
    (good clinical trials)
  • SIDE EEFECTS
  • bronchospasm, fatigue, bad dreams, cold
    extremities
  • worsening cardiac failure, heart block
  • hypoglyacaemia

37
ACE-inhibitors
  • ACTION
  • inhibits conversion of angiotensin I to
    angiotensin II - effects on vasculature in kidney
    , brain, heart
  • vasodilator
  • eg captopril, enalapril, lisinopril, ramipril
  • EFFECTS
  • lower blood pressure- relatively rapidly
  • effect on mortality, morbidity and
    complications??
  • Reduces mortality in cardiac failure, post-AMI
    good clinical trials

38
ACE-inhibitors
  • SIDE EFFECTS
  • cough, rash, taste disturbances
  • renal failure, neutropenia, proteinuria
  • COST
  • relatively expensive

39
Angiotensin II antagonists
  • losarten, ibersarten, candesarten
  • actions similar to ACE inhibitors
  • effects
  • lower blood pressure- relatively rapidly
  • effects on clinical outcomes?
  • Side effects
  • rash, cough
  • cost expensive

40
calcium antagonists
  • ACTION
  • three classes verapamil, dihydropyridines,
    benzothiazepines
  • block calcium entry into cells by preventing
    opening of voltage gated calcium channels
  • act on heart and smooth muscle, depending on type
  • vasodilator effect (mainly dihydropyridines)
  • two forms - immediate and slow release
  • EFFECTS
  • lower blood pressure - can be rapid
  • mortality, morbidity, complications??

41
Calcium antagonists
  • SIDE EFFECTS
  • flushing, headache, ankle swelling, constipation
  • heart block, worsening cardiac failure

42
choices
  • BENEFITS
  • short-term
  • long term
  • RISKS
  • side-effects
  • lack of beneficial effect ( unnecessary
    medication)

43
issues
  • Preventive versus curative treatment
  • need for joint decision making
  • use of drugs with clinical effects versus elegant
    pharmacologically active molecules
  • benefits versus risks!!

44
terms
  • agonist, partial agonist
  • receptor
  • antagonist, competitive antagonist
  • ligand
  • affinity
  • mediators
  • tolerance
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