Genomics and Medicine: The Physician’s View
Author and Curator: Larry H. Bernstein, MD, FCAP
Genomics has had a rapid growth of research into variability of human genetics in both healthy populations in the study of population migration, and in the study of genetic sequence alterations that may increase the risk of expressed human disease. This is the case for cardiology, cancer, inflammtory conditions, and gastrointestinal diseases. For the most part, genomics research in the last decade has shed light on potential therapeutic targets, but the identification of drug toxicities in late phase trials has been associated with a 70 percent failure rate in bringing new drugs to the market. Despite good technologies for investigative studies, initial work is carried out on animals and then the transferrability of the work from a “model” to man has to be assured. That is the first issue of concern.
Secondly, there is a well considered reluctance on the part of experienced and well prepared physicians to be “early” adopters to newly introduced drugs, with the apprehension that unidentified clinical problems can be expected to be unmasked. It is, however, easier to consider when a new drug belongs to an established class of medications, and it has removed known adverse effects. In this case, the adverse effects are known side effects, but not necessarily serious drug reactions that would preclude use.
A third consideration is the cost of drug development, and the cost of development is passed on to the healthcare organization in the purchasing cost. We can rest assured that the Pharmacy and Therapeutics Review Committee will not cease meeting on a regular schedule anytime soon. Further, how do the drug failures become embedded in the cost of the pharmaceutical budget passed on to the recipient. Historically, insurance is an actuarial discipline. But in the lifetime of an individual, they are bound to see a physician for acute or chronic medical attention. Only the timing cannot be predicted. As a result, dealing with the valid introduction of new medications is a big concern for both the public and the private insurer.
How does this compute for the physician provider. The practice of medicine is not quickly adaptive, as the physician’s primary concern is to do no harm. Genomics testing is not widely available, and it is for the most part not definitive for diagnostic purposes as things stand today. It may provide assessment of risk, or of survival expectation. The physician uses a step by step assessment, using the patient and family history, a focused physical exam, laboratory and radiology, proceeding to other more specialized exams. Much of the laboratory testing is based on the appearance in the circulation of changes in blood chemistry of the nature of electrolytes, circulating cells in the blood and of the blood forming organ, proteins, urea and uric acid. They are not exquisitely sensitive, but they might be sufficient for their abnormal concentrations appearing at the time the patient presents with a complaint. What tests are ordered is determioned by a need for relevant information to make a medical decision.
The relevant questions are:
1. acuity of symptoms and signs.
2. actions to be taken.
3. tests that are needed to clarify the examination findings.
once a provisional diagnosis is obtained, referrals, additional testing, and medication orders are provided based on the assessment.
Where does genetic testing fit into this? At this point, it will only be used
- to confirm a restricted list of diagnoses that have a high association with the condition, and
- only with the participation of a medical geneticist, when
- profiling the patient and other members of the family is required.
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