President's Column: Precisely!

By F. Todd Wetzel posted 01-03-2017 02:48 PM


In his annual State of the Union address on January 20, 2015, President Barack Obama announced the Precision Medicine Initiative (PMI). The National Institutes of Health were charged to begin planning, recruiting and initiating preliminary consultations with the goal of funding awards to begin recruiting participants in 2017. This is to serve as a major impetus behind data-driven research, encompassing the “intersection” of lifestyle, environmental and genetic factors to develop more effective ways to prolong health and treat disease in a patient-specific model. The italics are mine. From this executive order, the “All of Us” Research Model was created.

So, what exactly is “precision medicine”? A prime example of precision medicine is the manner in which the subspecialty of infectious disease has been transformed from the pattern recognition empiricism that has long characterized clinical medicine to a more logical and linear process:

identification of the infected area or organ system (assessment), isolation of a specific pathogen (diagnosis), administration of a specific treatment (antibiotic) shown to be effective against the particular pathogen an outcome (resolution).1

This model has become more “precise” with molecular medicine, as in oncology. It is intuitively and logically obvious that such a model is intended to promote the customization of health care, with decisions, practices and other components. The concept also involves extensive refinements of diagnostic techniques to the genetic and molecular levels, again primarily addressing oncologic issues. The tools of the model include all of the tools of molecular medicine (panomic analysis), eg, systems biology, and computational and mathematical modelling of biological systems. This is comprehensive, as noted above, with data collection and factor analysis from external systems, such as environment (exostome) right down to the molecular interactions in a single cell (interactone). Thus precision medicine is, in a sense, the ultimate deductive model, starting big and ending small—the tissue microenvironment. This is truly a new paradigm of patient care and is in a logical sense in direct contrast to the inductive reasoning traditionally applied to clinical decision-making.2

How does this model impact spine care? Profoundly. Despite the molecular endpoints and oncologic heritage, the fundamental premise of precision medicine is not the literal creation of drugs or devices that are unique to an individual patient, but a specific data-driven subgroup classification. We already do this in many instances. For example, the literature is quite convincing that in the case of the subgroups of patients with neuroclaudication due to lumbar spinal stenosis who also have degenerative spondylolisthesis, all of whom have failed appropriate nonoperative care and have signs and symptoms consistent with neuroclaudication, the addition of arthrodesis to the primary decompression will improve outcomes.3

However, even in this apparently clear instance, numerous underlying assumptions are implicit. In the ideal case, the assessment and diagnosis are specific: degenerative spondylolisthesis and lumbar stenosis causing the symptoms of flexion responsive axial pain and neuroclaudication, respectively (concomitantly?). The treatment—decompression and arthrodesis—results in patient-based outcome “successes” at a frequency of 85% in one surgical subgroup.3 Good, but as Dr. Christopher Bono mentioned in his recent presidential address in Boston, even 85% is really not something that he would accept. Nor should any of us.

*This is an excerpt from Dr. Wetzel's column in the November/December 2016 issue of SpineLine. Click here to read the full column.