Epi07_2

=Fundamental ideas and basic vocabulary= Idea 1: Non-specialists need to become comfortable with the fundamental ideas and basic vocabulary of epidemiology in order to converse intelligently with specialists in epidemiology and biostatistics. One way to move in that direction is to practice making the ideas accessible to the layperson.

**Notice the series of activities listed in the syllabus, including explaining Rose’s article to each other.**
Key concepts in statistics (provisional basis for mini-lecture) > Central tendency and dispersion > Data reduction (summary, descriptive statistics, factors) > Differences between means > Patterns, predictions, and causes > Experimental interventions and naturally variable observations > Multiple variables, multiple groups

Key terms/concepts in epidemiology (provisional list; see also [|helpful introduction and glossary])

> Prevention: Primary, secondary, tertiary > Population vs. individual focus > Multi-step process in epidemiological reasoning > What is a case?: Discrete, continuous, stages > Cross-tabulation > Incidence, prevalence, risk > Target population, study population,study sample > Rates, incl. morbidity vs. mortality > Sensitivity vs. specificity > Positive predictive value > Outcome measures > Modes of comparison: historical, non-randomized control, RT > Cohort, case-control, cross-section > Associations: Odds ratio, relative risk, attributable risk > Bias, confounding, conditioning, interaction > Ecological fallacy and atomistic fallacy

Idea 2: In advising on the most effective measures to be taken to improve the health of a population, epidemiologists may focus on different determinants of the disease than a doctor would when faced with sick or high-risk individuals.

Rose promotes the population health focus, but this is not universally accepted by healthcare practitioners and policy makers. Can you identify areas in your own life and/or work when you would take a population view and other areas where your focus would be individually-centered?



(not a) Substantive statement
Example raised in class: Controversy over vaccination of girls for HPV. Question: What would Rose propose?

Question in class: Why isn't a population an aggregation of individuals and thus population risk = sum of individual risks? PT's response: It is necessary to think of different meaning of "treatment." A sick individual is treated by a physician to cure or reduce the effects of the disease. Population health policies do not treat a large group of sick people, but attempt to reduce the incidence in the next generation. A physician treating sick individuals adjust the treatment if it doesn't work well for certain individuals. Public health measures usually discount the heterogeneity in the population and apply the same policy to all. It is possible, however, to imagine that knowledge of heterogeneous responses to treatment of individuals could lead to more effective population health policies (and reduce the kickback that occurs when some individuals claim to have suffered under the population health policy).

(11/07) Road accidents and alcohol consumption may be a good illustration of Rose's argument. Most of us know of getting home safely when we've drunk too much "risk factor," but we also know that a substantial fraction of people in accidents have high alcohol levels. We also sense that some people are more susceptible to having their judgement and reaction times impaired by alcohol so we could imagine doing further epi & biol research to develop multivariable risk factor formulas. Would a more refined knowledge of riskiness help us prioritize our risk-prevention efforts, or would that pale into insignificance relative to a Rosean drink-don't-drive efforts?...



Annotated additions by students
Buetow S, Docherty B. The seduction of general practice and illegitimate birth of an expanded role in population health care. //Journal of Evaluation in Clinical Practice// 2005;**11**(4):397-404.

While this article does not directly review any of Rose's articles or books, it more broadly reviews the idea of population health with Rose as an anchor. It further attempts to use Rose's arguments, in particular his theorem ("a large number of people at small risk may give rise to more cases of disease than a small number who are at high risk) to argue that a population health approach subverts clinical practice at the expense of patient care. The authors argue that a focus on population health contributes to sub-par personal care and an erosion of the sacrosanct doctor-patient relationship. Additionally, they argue that public health interventions remain largely untested, or at least have so far failed to demonstrate broad-scale efficacy. Using overweight as an example of the follies of population health approaches, the articles suggests that population health advocates are not only confusing disease outcomes with social phenomena, but that doing so may actually reverse Rose's theorem such that small alterations in the health of populations based on untested public health interventions could actually cause greater harm to individuals. The article fails to really assassinate Rose's argument fully however, as it poses clinical health against population health in an all-or-nothing competition, whereas Rose begins his argument with an appeal to clinical practice and the lessons it conveys. Essentially, Rose's message is twofold, that we must seek both the causes of cases and the causes of incidence, but that the latter takes priority as such pursuit is likely to create greater overall benefit. His argument does not contain the seeds of demise for clinical health; thus the article referenced herein argues against a straw man rather than taking into account the more complex nature of Rose's argument for population health. (lh)

Charlton, Bruce. (1995). A critique of Geoffrey Rose’s ‘population strategy’ for preventive medicine. //Journal of the Royal Society of Medicine,// 88, 607-610.

Charlton remarks on the published works of Rose, particularly his views on “population strategy” and its impact on public health. However, he states that although Rose’s beliefs have been accepted in the public health realm, he believes there are issues/problems with Rose’s ideas which he further expounds in his commentary. He argues against Rose’s theory of differences between //determinants of individual cases vs. determinants of incidence rate of a disease in a population;// stating there is no direct evidence to support this theory. He does not believe a population should be compared to a patient, as this only shifts the conclusion from individual risk to population risk. He also argues against Rose’s policy of prevention which is based on reducing many risk factors which could benefit larger populations but not necessarily making any difference to individual health. Rose would contend that measures to improve public health should be planned by government, whereas Charlton argues that this would increase government involvement in too many aspects of individual lives. Although Charlton recognizes Rose’s work as a major contribution to health promotion, he presents many aspects of Rose’s beliefs regarding sick individuals and sick populations with very direct counterarguments supporting his (Charlton’s), theories on these same topics. (SA)

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