Health risks, evidence and treatment: exam questions

• (i) positive correlation / as percentage of smokers rises, CHD death rate rises (1)
• quotes figures, e.g. from 95 at 12 % to 215 at 38 % (1)
• (ii) (215 − 95) ÷ 95 × 100 (1)
• = 126 % (1)
• (iii) correlation does not show causation (1)
• other variables (for example diet, age, exercise, or other differences between regions) could affect death rate / data are for regions not individuals (1)

• different sample sizes / different groups of people studied (age, gender, ethnicity) (1)
• different ways of measuring salt intake (self-reported or measured) (1)
• different lengths of study / different variables controlled (1)
• chance / one study may have had bias (1)
• Max 3

• sample is small, so results are not reliable / more affected by chance (1)
• volunteers from one gym are not representative of the population / are likely to be health-conscious, so bias (1)
• diet recalled from memory / self-reported, so not valid / not accurate (1)
• no control group / other variables (exercise, smoking) not controlled / short duration, so cannot conclude low-fat diet prevents CVD (1)
• Max 4

• the harm builds up over many years / long delay before disease appears, so people feel healthy now (1)
• people enjoy / are used to the behaviour, or think it will not happen to them (1)
• they see relatives or others who did not develop the disease (personal experience) (1)
• media focus on more dramatic risks / statistics are not well understood (1)
• Max 3

• (i) person B (1)
• highest total cholesterol (6.8) and highest LDL (4.9) (1)
• lowest HDL (0.9) / highest total cholesterol : HDL ratio (7.6) (1)
• (ii) HDL carries cholesterol from the tissues / artery walls to the liver (1)
• so less cholesterol is deposited in the artery wall / less atheroma forms (1)

• population studies show higher CVD rates in people with higher total / LDL cholesterol (1)
• people with inherited very high cholesterol develop CVD at a young age (1)
• LDL is found in plaques / the mechanism of foam cell formation is known (1)
• trials show lowering LDL (for example with statins) reduces heart attacks and strokes (1)
• Max 4

• BMI = mass ÷ height² = 92 ÷ 1.80² (1)
• = 28.4 kg m⁻² (1)
• waist-to-hip ratio = 104 ÷ 100 = 1.04 (1)
• ratio above the 0.85 commonly used for women, so higher risk (excess abdominal fat) (1)

• reduce saturated fat in the diet to lower LDL cholesterol / less atheroma (1)
• reduce salt to lower blood pressure (1)
• take regular exercise to lower blood pressure / raise HDL / control body mass (1)
• do not smoke, to avoid carbon monoxide / nicotine / endothelial damage (1)
• use BMI or waist-to-hip ratio to monitor body mass (1)
• Max 4

Answer: C – they lower blood LDL cholesterol

• statins lower LDL cholesterol by reducing cholesterol production in the liver (1)
• so slow atheroma formation / reduce the risk of heart attack and stroke (1)
• risks of statins: muscle pain / digestive upset / rarely liver damage (1)
• platelet inhibitors stop platelets sticking together (1)
• so reduce clot formation in arteries / risk of heart attack and stroke (1)
• risks of platelet inhibitors: bleeding / stomach irritation or ulcers (1)
• treatment decided by weighing benefit against risk for each patient, with lifestyle changes (1)
• Max 6