Speaking Notes

PADM 5324

October 27, 2009

Dr. Neubauer

• I have read your homework assignments. They are each thoughtful and reasonable. It would have been better if this assignment had come later in the semester in order that you could have more fully incorporated the distinction between cohort studies and case-control studies in your papers.
• I may write two more homework assignments, as per the syllabus. If not, you will get credit for any of the three homework assignments not given.
• I hope your group paper is coming along well.
• We are behind the calendar, but there are some "catch up" days ahead.
• Do you have any "in the news" reports this evening?

The key terms in this chapter (Chapter 12) are the following:

Incidence rate is usually expressed per 1,000 people in the relevant population.

Background risk is the risk that every person shares whether or not he/she has been exposed to a possible cause.

Attributable risk is the additional risk (above background risk) that can be attributed to exposure to a possible cause.

Total risk is the sum of background risk and attributable risk.

Attributable risk indicates the potential for prevention if the exposure could be eliminated.

These concepts are important in both PUBLIC HEALTH and in CLINICAL PRACTICE. In a physician's clinical practice the focus is on an individual patient. In PUBLIC HEALTH the focus is upon groups of people -- the relevant POPULATION, however defined.

These concepts are also relevant to TOXIC TORT LITIGATIONS. This is likely to take the form of a specific INDIVIDUAL claiming ENVIRONMENTAL INJURY which may have be caused by a specific company. The legal requirement is the "more likely than not" standard. If ATTRIBUTABLE RISK is greater than 50 percent, that may amount to evidence that the "more likely than not" standard has been satisfied.

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The book uses the example of coronary heart disease (CHD) and smoking. Smoking is a cause of CHD.

However, some people who have never smoked die of CHD (background risk).

There is a higher incidence rate of CHD among populations of people who smoke.

Therefore, there is an attributable risk to smoking regarding CHD.

Physicians advise individual patients to not smoke in part because it is reasonable to assume that THE ATTRIBUTABLE RISK APPARENT IN POPULATIONS TRANSLATES INTO AN ATTRIBUTABLE RISK TO INDIVIDUALS.

A patient who does not smoke still has a risk of CHD, which is defined as being BACKGROUND RISK.

Not smoking is not a guarantee that one will not get CHD.

The benefit of not smoking (regarding risk of CHD) is not the measure of total risk but is the measure of attributable risk (inferred from studies of populations of people).

The larger the proportion of total risk explained by attributable risk, the more important it is for individual patients to change their behaviors in prescribed ways.

BACKGROUND RISK

ATTRIBUTABLE RISK

The origins of BACKGROUND RISK are likely to be beyond the control of individuals. Therefore, a PUBLIC HEALTH campaign focused exclusively on INDIVIDUALS changing their personal behaviors is likely to "MAX OUT" in terms of its SOCIAL VALUE as a percentage of its affects on attributable risk.

This is kind of like the distinction between micro economics and macro economics. Micro economics is entirely about how individuals behave (economically) within an economic system that is assumed to be fixed.

Macro economics is about how high-level POLICY MAKERS can make changes in the entire system itself.

CLINICAL PRATICE is kind of like micro economics

PUBLIC HEALTH is kind of like macro economics.

If the decisions of individuals have consequences (positive or negative) for others, there are EXTERNALITIES associated with the choices made by individuals.

In an example in our textbook, the author assumes that the total possible benefits of a program to enable people to stop smoking is the impact on their ATTRIBUTABLE RISKS associated with smoking. In other words, there will be NO EFFECT ON NON-SMOKERS and smokers will still have the BACKGROUND RISK of various diseases associated with smoking. This is like micro economics.

I think the author of our textbook is assuming a DICHOTOMY between CLINICAL PRACTICE and PUBLIC HEALTH, in the same way that economists apparently assume a DICHOTOMY between microeconomics and macroeconomics.

It is true that ONE PERSON who stops smoking will have no impact on BACKGROUND RISK.

However, I would argue that there are EXTERNALITIES associated with smoking and that a PUBLIC HEALTH campaign that "causes" many people in a population to stop smoking may in fact LEAD TO A REDUCTION IN BACKGROUND RISK and therefore benefit not only those who stop smoking but those who have never smoked.

Going back to economics, it is true that no one person can affect the economy of a nation. But if MANY PEOPLE independently do the same thing COLLECTIVELY their behavior can have an effect at the MACRO LEVEL.

Malcolm Gladwell describes this in his book, The Tipping Point: How Little Things Can Make a Big Difference. What begins as a unitary oddity can "catch fire" and can literally change the world. This is especially true in the present age when people and information move around the globe very quickly.

In the case of smoking, I think the BACKGROUND RISK can be reduced be because SMOKING HAS A NEGATIVE EXTERNALITY THAT (I think) CONTRIBUTES TO THE BACKGROUND RISK OF NON-SMOKERS IN THE POPULATION.

Let's ASSUME that SECONDARY SMOKE contributes to CHD in nonsmokers. If so, this is certainly a NEGATIVE EXTERNALITY associated with smoking. If this is true, then IF ENOUGH PEOPLE in a population stop smoking not only will their ATTRIBUTABLE RISK drop but the BACKGROUND RISK of nonsmokers may drop also.

So, if you are doing to do a COST BENEFIT study regarding some intervention intended to help a SUBSTANTIAL PERCENTAGE of smokers stop, then the question becomes,

1) is the benefit only the benefit of a reduction of attributable risk to smokers who stop, OR

2) should the calculation of the benefit INCLUDE a reduction in BACKGROUND RISK among nonsmokers in the population?

IN OTHER WORDS, what is scope of benefits associated with smokers stopping? Are they the sole beneficiaries or do non smokers also derive a benefit?

The benefits of MANY PUBLIC POLICIES "SPILL OVER" to others who are not the directly intended beneficiaries. Medicare and Medicaid, for example, can indirectly benefit children of elderly parents who might otherwise have to sacrifice their careers in order to provide care for parents.