Prevention Paradox Flashcards
Clinical Medicine & The Individual -Centered approach:
- Medicine focuses on the reasons why THIS patient got THIS disease at THIS TIME
- “Normal” ranges based on what is common in the local population, even if it doesn’t represent the entire human population
- Assumes heterogeneity in the exposure
- –The more widespread a cause, the less it explains the distribution of cases
Rose’s Approach:
- Seeks the causes of incidence, not just the cause of cases
- –Why do some populations have much hypertension, whist in other’s it is rare? - Seeks patterns and trends in incidence across populations
- How can we shift the bell curve to lessen disease
The Prevention Paradox
A large number of people at modest risk may give rise to more cases of disease than a small number of people at big risk
(Therefore we should not only focus on the high risk populations, bc then we are missing the majority of cases from those in the low risk group)
Population Attributable Risk (PAR):
What are the 2 parameters PAR depends on?
- The excess amount of disease in the study population that is attributable to the exposure
- Depends on relative risk & prevalence:
- -When RR is large, PAR may not be high if the prevalence of the exposure is low
- -When RR is low, PAR may be high if the exposure is highly prevalent
Implications of Prevention Paradox for Prevention
Individual strategy = seeks to identify high risk susceptible individuals and offer individual protection
Population strategy = seeks to control the determinants of incidence in the population as a whole
High Risk Prevention Strategy
Goal = to eliminate the high risk tail of distribution, to relieve those who are high risk without interfering w/the general population
Action = identify those in special need
Prevention:
- Controlling the level of exposure to a risk factor (ie reducing house dust)
- Providing protection against the effects of exposure in order to forestall complication (ie vaccine)
High Risk Prevention Strategy
Strengths
- Large individual benefit
- Intervention matched to individual, which increases motivation to adhere
- No interference in the lives of low risk group
- Fits into 1:1 medical care model
- Individual prevention efforts are cost effective for those at high risk
High Risk Prevention Strategy
Weaknesses
- Low population benefit
- Labeling of individual via medical conditions
- Asking high risk individuals to engage in non-normative behaviors
- Can’t predict the future w/ accuracy at the individual level (most in high risk group will remain well, while many in the low risk group will get sick)
- Eliminating risk factors may not be possible - hazardous circumstances causing illness may not change
- Feasibility and cost of screening is problematic
Population Strategy
Goal = to control the underlying determinants of ill health and shift the entire distribution
Each pop has its own characteristics. When they change, their distributions shift as a whole
Population Strategy
Strengths
- Radical-can address the root causes
- Powerful-large overall population benefit from small individual changes
- Appropriate - easier to change with social norms, doesn’t buck against them
- Less victim blaming
Population Strategy
Weaknesses
Acceptability - individual benefits of change unlikely to be noticed to an individual –decreases motivation for change
Feasibility-changing social norms is difficult
Cost + Safety - costs incurred at time of intervention, but benefits are not immediate
Trade off between High Risk and Population Prevention Strategies
High risk - big individual benefit, modest population benefit
Population - small individual benefit, big population benefit
Abnormality & Normality
Abnormality cannot be separated from normality - they move up and down as a whole
The mean drives the tail of the distribution
Relation of Means and Tails
Knowing the mean of a normally distributed risk factor allows you to predict the extremes of the distribution
Deviance is defined by the norms
Norms are the features of society
Implications for Population-Level Change
- Structural changes to the environment
- Legislative and regulatory controls
- Fiscal policies
- Reducing price barriers for preventive goods and services
- Improved access to preventive health services
