“If Not Genetics, Then What?”

Originally posted 9/4/2012

“If Not Genetics, Then What?” is the title of Chapter 6 in the important 1994 population health book Why Are Some People Healthy and Others Not: The Determinants of Health of Populations. Canadian population health geneticist Patricia Baird contributed a chapter on “The Role of Genetics in Population Health,” which concludes as follows: “There are some disorders where the inherited metabolic machinery of the individual will not allow normal functioning in the usual range of environments; the associated diseases will usually burden the earlier part of the human life cycle. These provide a real and appropriate place for genetic service programs to contribute to population health. The complexities of the web of causation for most common afflictions in adult life are likely to limit the contribution of DNA identification of at risk genotypes. The potential for wasting resources and causing harm is real and serious.”

I was prompted to return to this seminal text several weeks ago after a series of New York Times articles on modern genomics that included a front page story on tailoring treatment for leukemia to a business page report of approval in Europe of a gene therapy for treating a rare enzyme deficiency. Genetic studies on Alzheimer’s proteins in mice have also raised the hope for a similar way to way to cure or slow the progression of this serious and increasingly prevalent health issue. The growing availability to sequence complete individual human genomes raises the potential of widespread “personalized medicine,” with drugs or genes available for whatever defects any person might have.

How is a population health advocate to think about the possibility of such scientific advances to improve overall health and reduce disparities? It is so tempting to be lured into the fascination and the hope of such technological cures, but why do I have significant reservations? It probably because of the ideas laid out by Geoffrey Rose in his classic article “Sick Individuals and Sick Populations” in which he asserts that “a large number of people at small risk may give rise to more cases of disease than the small number who are at high risk.” While there may be important advances with life-saving treatments for rare diseases such as mentioned above, many complex diseases like diabetes and obesity may have their genetic defects spread over many locations rendering therapy complex and less likely, and many are the result of complex gene-environment interactions. The best thinking such as from CDC Public Health Genomics expert Muin Khoury, who argued for expanded evidence-based strategies in a 2008 Health Affairs article: “the current low threshold allows unsubstantiated technologies to enter into practice with the potential to overwhelm the health system…while an excessively high threshold for evidence could slow the integration of genomics into practice…also, variable coverage and reimbursement policies can lead to differential access to technology, exacerbating health disparities.”

Baird’s warning about wasting resources and causing harm needs to be taken seriously. As Don Berwick says, “waste is theft.” It is not anti-scientific to worry that our American belief in technology and venture capitalism could result in much waste, while less expensive investments we already know to be effective are ignored.  The problem is that it is hard to predict the future, and decades from now there will certainly be important benefits from genomic research, including both treatments and preventive interventions.  We can only insist that the most careful evidence on population health cost-effectiveness be used to guide investments, rather than the potential for profit from very expensive therapies that benefit few.

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