Physical inactivity has a relative risk of approximately 1.5 for heart disease, while a rare genetic variant confers a relative risk of 10. For population-level prevention policy, which is likely the more important target and why?
AThe genetic variant, because its relative risk is nearly seven times higher
BPhysical inactivity, because its high prevalence means its population attributable risk is far greater
CThe genetic variant, because high-risk individuals benefit most from targeted intervention
DPhysical inactivity, because behavioral risk factors are always more modifiable than genetic ones
Population Attributable Risk (PAR) depends on both relative risk and prevalence. Physical inactivity affects a large fraction of the population, so even a modest relative risk translates into a huge attributable burden. The rare genetic variant, despite its strong effect on individuals carrying it, affects so few people that eliminating it would prevent relatively few cases. This is the core tension Geoffrey Rose identified between high-risk and population strategies.
Question 2 Multiple Choice
A public health agency in a rapidly urbanizing country wants to project future cardiovascular disease burden. The most important methodological reason to track current tobacco and dietary exposure patterns is:
ATobacco and diet directly cause cardiovascular events within weeks of exposure
BCross-sectional surveys of current disease prevalence are unreliable without this data
CNCD latency means today's exposures will determine disease burden decades from now
NCD latency — often 20–40 years between exposure and clinical disease — means that the cardiovascular disease prevalent today reflects exposures from decades past, and future disease burden will reflect current exposures. Tracking present risk factors allows projection of future burden and identification of prevention windows before the disease wave arrives.
Question 3 True / False
A risk factor with a relative risk of only 1.3 can still account for a large proportion of NCD cases in a population.
TTrue
FFalse
Answer: True
True. Population Attributable Risk is a function of both effect size and prevalence. If 60% of the population is exposed to a risk factor, even a modest relative risk like 1.3 translates into a substantial proportion of cases. This is why sedentary lifestyle and processed food consumption — ubiquitous in modern populations — can dominate the NCD burden despite having lower relative risks than rarer, stronger exposures.
Question 4 True / False
The most effective NCD prevention strategy generally targets the highest-risk individuals, because they experience the greatest absolute risk reduction from intervention.
TTrue
FFalse
Answer: False
False. This is exactly the misconception Geoffrey Rose challenged. High-risk strategies may benefit individuals intensely but reach few people. Population-wide strategies that shift the entire risk distribution — even by small amounts — can prevent far more total cases, because the majority of cases arise from the large mass of people at moderate (not extreme) risk. The 'prevention paradox' is that interventions offering small individual benefit can produce large population benefit.
Question 5 Short Answer
Explain why the decades-long latency between NCD risk factor exposure and disease creates structural incentives that work against prevention investments.
Think about your answer, then reveal below.
Model answer: Prevention investments made today will not reduce disease burden for decades, long after the political cycles of those making the decisions. Governments and funders respond to outcomes on short timescales, while NCD prevention payoffs are measured in generations — creating a rational (if shortsighted) bias toward treatment over prevention.
This is one of the most practically important insights in NCD epidemiology: the same latency that makes causal inference hard also makes prevention politically difficult. A politician who funds smoking cessation programs will not see reduced lung cancer rates within their term. This temporal mismatch between investment and visible return structurally disadvantages prevention relative to treatment in resource allocation decisions.