Geoffrey Rose proposed two approaches to etiology and their counterparts in preventions.
Distinguish two kinds of etiological question
The question “why did this patient get this disease at this time?” is quite different from the questions “why did this happen to some population whilst in others it is rare and could it have been prevented?” The first seeks the causes of the cases and the second seeks the causes of incidence. Epidemiology is a study of the determinants of the disease distribution, while Rose believed that the more widespread a determent, the less it explains the distribution of cases.
Two prevention strategies
- The “high-risk” strategy seeks to identify high-risk susceptible individuals and to offer them individual protection.
- The population strategy seeks to control the determinants of incidence, to lower the mean level of risk factors, to shift the whole distribution of exposure in a favorable direction.
|high-risk||Intervention appropriate to individual||Difficulties and costs of screening|
|Subject motivation||Palliative and temporary- not radical|
|Physician motivation||Limited potential for (a) individual (b) population|
|Cost-effective use of resources||Behaviorally inappropriate|
|Benefit: risk ratio favorable|
|population||Radical||Small benefit to individual (“Prevention Paradox”)|
|Large potential for population||Poor motivation of subject|
|Behaviorally appropriate||Poor motivation of physician|
|Benefit: risk ratio worrisome|
A Durkheimian perspective
As S Schwartz and R Diez-Roux pointed out, the central lesson that has been integrated into the field is that “a large number of people at a small risk may give rise to more cases of disease than the small number who are at high risk”.
They also pointed out it is important to see Rose’s understanding of the relationship between wholes and parts- between population and individuals of which these population are comprised from a Durkheimian perspective (i.e. the population has characteristics that are distinct from the summation of the characteristics of all the individuals in the population although population comprised of individuals. The characteristics of the population may be influenced by characteristics of the individuals but the characteristics and behaviors of the individuals are also shaped by the characteristics of the population. They summarized five situations in which causes of incidence and causes of cases warrant separate consideration.