Cardiovascular risk factors
Name two modifiable risk factors for ischaemic heart disease.
Smoking
Hypertension
Hyperlipidaemia
Diabetes
Obesity
Sedentary lifestyle
Define hypertension (clinic BP threshold in UK)
≥140/90 mmHg
A patient is started on amlodipine for hypertension.
What class of drug is this?
Calcium channel blocker
What is decision analysis
Decision analysis is a systematic, explicit,
quantitative way of making decisions in health care
that can … lead to both enhanced communication
about clinical controversies and better decisions
A 52-year-old man with BMI 32, smokes 20/day, and has BP 150/95 mmHg. Which single intervention would give the largest reduction in cardiovascular risk?
Smoking cessation
What is the role of the kidney in long-term blood pressure regulation?
Regulates blood pressure via sodium and water balance and activation of the renin–angiotensin–aldosterone system (RAAS)
According to UK guidelines, how does age and ethnicity influence first-line antihypertensive choice?
<55 and non-Black → ACE inhibitor/ARB
≥55 or Black ethnicity → calcium channel blocker
Limitations of decision analysis
Probability estimates:
• Required data sets to estimate probability may not exist
• Subjective probability estimates are subject to bias:
over-confidence & heuristics (biases)
Utility measures:
• Individuals may be asked to rate a state of health they have not experienced
• Different techniques will result in different numbers
• Subject to presentation framing effects (e.g. survival / death)
• The approach is reductionist (e.g. stroke outcomes as binary: ‘affected’ or ‘unaffected’
Why does age have such a strong influence on cardiovascular risk scores, even in otherwise healthy individuals?
Because cardiovascular risk is cumulative over time, reflecting prolonged exposure to risk factors and progressive vascular damage
Even without major risk factors, ageing increases arterial stiffness, endothelial dysfunction, and baseline risk
Explain how activation of the renin–angiotensin–aldosterone system (RAAS) increases blood pressure.
Angiotensin II: vasoconstriction
Aldosterone: sodium and water retention - increased blood volume + systemic vascular resistance
What is the mechanism of action of thiazide diuretics in lowering blood pressure?
Inhibit sodium reabsorption in the distal convoluted tubule → decrease plasma volume → decrease blood pressure
What are the benefits of decision analysis
Makes all assumptions in a decision explicit
• Allows examination of the process of making a
decision
• Integrates research evidence into the decision
process
• Insight gained during process may be more
important than the generated numbers
• Can be used for individual decisions, population
level decisions and for cost-effectiveness analysis
How does chronic hyperlipidaemia contribute to atherosclerotic plaque formation at the endothelial level?
LDL infiltrates endothelium → oxidised → triggers inflammation → macrophage uptake → foam cells → fatty streaks → plaque formation
A patient with resistant hypertension is found to have renal artery stenosis.
Explain how this leads to hypertension.
Reduced renal perfusion → increased renin release → RAAS activation → systemic vasoconstriction and fluid retention
The kidney interprets low perfusion as low blood pressure, even when systemic BP is high
A patient started on a calcium channel blocker develops flushing and headaches.
Explain the mechanism behind these symptoms.
Vasodilation of peripheral blood vessels → increased blood flow → flushing and headache
What is sensitivity analysis and when is it necessary
Sensitivity analysis in decision analysis is a "what-if" technique that determines how uncertainty in input variables impacts the final decision
It's necessary when the numbers are uncertain. Done by varying uncertain variables over a plausible
range so can calculate the effect of uncertainty on decision
Explain the pathophysiological link between hypertension and atherosclerosis.
Hypertension causes endothelial damage, increasing permeability to lipids and promoting inflammation → accelerates atherosclerosis
A patient with hypertension is treated with a diuretic. Initially their blood pressure falls, but over time it begins to rise again despite continued treatment.
Explain the physiological mechanism behind this.
Diuretics reduce blood volume → decreases BP initially → compensatory activation of RAAS → vasoconstriction + sodium retention→ partial return of blood pressure
A patient with hypertension is found to have bilateral renal artery stenosis.
Which class of antihypertensive should be avoided and why?
ACE inhibitors
They reduce efferent arteriolar constriction → reduces glomerular filtration pressure → can cause acute kidney injury
What are the 5 stages in a decision analysis
1. Structure the problem as a decision tree -
identifying choices, information (what is and is
not known) and preferences
2. Assess the probability (chance) of every choice
branch
3. Assess (numerically) the utility of every outcome
state
4. Identify the option that maximises expected
utility
5. Conduct a sensitivity analysis to
explore effect of varying judgements