Cart Before The Horse?
Among the items mentioned by Kohane, one that immediately caught my eye was that of "accuracy," which the author mentions as the closest to being within our grasp. The entire article is pretty much equating "precision medicine" with genomics, that is, gene sequencing as the key to unlocking all medical maladies.
First, let me define precision medicine. Precision medicine means that the doctor gets something off the shelf that the doctor thinks is precisely what you need. Precision medicine is not "personalized medicine," which purports to have a treatment that is made for you alone, to the exclusion of all the other billions of us on the planet here with you. Unfortunately, this distinction is rarely made and the two terms are frequently used to mean the same thing: Putting you into a diagnostic niche for which there is a “precisely” well defined prognosis and a limited number of (hopefully) effective therapeutic options.
My concern with the article by Kohane is that currently medical laboratories have a reasonably difficult time producing accurate results on the most basic of laboratory tests, for example, blood counts, electrolytes (such as sodium and potassium) and TSH (Thyroid Stimulating Hormone), tests which are run millions of times a day, 365 days a year. All of these and hundreds of other common lab tests are submitted to the FDA for approval before they can go into diagnostic laboratories for routine clinical assessment. Even though “accuracy” for these tests can be a challenge to achieve, at least the statistical parameters and large populations studied give a rational basis for understanding the issues with obtaining “accuracy.”
But for the vast majority, if not all, of these new genomic tests, there has been absolutely no approval process whatsoever through the FDA, because these tests are called “Laboratory Developed Tests,” or LDTs. We have basically no idea of how these tests were identified as useful, how the tests are actually performed, the statistical basis for determining what is normal (how many individuals who are supposedly normal, or the reference population, were studied), how reproducible the tests are (technical statistical term is, alas, “precision,” which has no relationship to the use of the same word in the term “precision medicine.”)
In my recently published eBook, “Blood Trails. Follow your medical lab work from beginning to end with everything that can go wrong in between. Plus How doctors misunderstand and misuse blood tests,” I discuss all of the issues that can go wrong with routine medical lab tests and I discuss the barren wilderness of LDTs, of which the best I can offer is to quote Dr. Johsua Sharfstein (JAMA 313: 667-668, 2015): “A patient travels by an ambulance that is regulated, to a hospital that is regulated, for care using medicines that are regulated, administered by nurses and physicians, who are regulated. Yet today, that same patient’s life or death could hinge on whether a single, un-regulated diagnostic test result is meaningful.” That’s correct, these tests are currently unregulated by the FDA, although the agency is promising to do something about the lack of regulation. FDA has published a draft framework concerning phasing in of regulations of LDTs, but powerful industry forces with expensive, high-profile attorneys like Paul Clement and Laurence Tribe are challenging FDA’s authority to regulate LDTs.
Another big concern I have with the emphasis on so-called “precision medicine” is the assumption being made that sequencing your genome is going to provide all the diagnostic, prognostic and therapeutic information you and your doctors will ever need. I am not at all sure that is the case. As I mention in my book “Blood Trails,” it might be far more cost effective to do relatively easy tests which can tell you pretty much how long you are going to last. Those tests discussed in my book are: Hemoglobin A1c, Free Light Chains, and Brain Natriuretic Peptide.
I will discuss these tests in subsequent posts.
© 2015 Ralph Giorno