Taking the Guess Work Out of Prescriptions
Though not everyone is familiar with the term “pharmacogenomics,” it is undoubtable that the science behind this emerging field is benefitting patients. In short, pharmacogenomics is genetic drug matching to fit an individual’s DNA. This process is called drug-gene testing. Testing for drug-gene results allows doctors to see how certain genes react to medications thus helping doctors prescribe the most effective medication at the proper dosage, tailored to an individual’s genetic makeup. The benefit of drug-gene testing is a reduction of people becoming ill due to an adverse reaction to a prescription and dosage.
Studies from St. Jude Children’s Research Hospital and Vanderbilt University Medical Center show, “Roughly 50 percent of hospital patients get a drug in any one-year period that could cause serious side effects because of that person’s genetic makeup.”1 A study at Vanderbilt, which examined only six drugs, estimated that drug-gene tests could eliminate some 400 adverse events in a patient population of 52,942.1 A different study, published in the October 2015 edition of Nature, showed many drug-gene interactions - both severe and subtle - could be avoided by taking different doses of the drugs or turning to substitutes. Researchers concluded that there are 80 medications-affected by about two dozen genes-with known alternative treatments.1 With positive results from these studies, the question is: Why aren't patients drug-gene tested routinely? There are two reasons: 1. Insurance companies currently do not cover a large percentage of the cost of drug-gene testing and 2. Doctors are not familiar with prescribing medication based upon genetics.
Insurance companies have been reluctant to cover drug-gene tests because they believe the cost of the test is not equal to or greater than the benefit received from the test. Total human genome sequencing costs $1,000 but drug-gene results on a few hundred genes at St. Jude costs about half as much.1 Clare Krusing, a spokesperson for America’s Health Insurance Plans (the national trade association for the health insurance industry) stated: “Coverage does vary for these tests as a result of limited clinical evidence around their effectiveness for patients.”1 However, in the past few years, Vanderbilt reports some insurance companies are beginning to change their reimbursement policies by covering a small portion of the cost of the test.1
Another roadblock to drug-gene testing is doctor’s lack of knowledge regarding drug-gene testing. Doctors are taught to look at factors such as age, weight, renal and liver function. They also look at the patient’s current prescriptions and may take into account a patient’s medication preference before they prescribe medication. Drug-gene research is relatively new; some of the major recent research milestones about drugs and genes have been reached at St. Jude by Mary Relling, chair of the pharmaceutical sciences department.1 Relling and her colleagues conducted years of drug-gene tests on a small scale.1 Her research led to St. Jude standardizing drug-gene testing for all new patients. In March St. Jude had data in almost 3,000 patients’ electronic medical records corresponding to seven genes and 23 drugs that are well understood and affects its patients.1 Research studies such as Mary Relling’s are new to the medical community, and medical schools have yet to include drug-gene testing and its benefit to patients in their curriculum. Due to the lack of education in drug-gene testing and its implications, doctors are not accustomed to taking genetic factors into account when prescribing medication. The benefit to drug-gene testing is it allows the doctor to see genetic variations and adjust dosages or medications to what would best work for the patient.
Drug-gene testing must be standardized. With more research, increased education amongst doctors and proof of patients benefitting from drug-gene testing the obstacles facing testing should cease to exist. Doctors need to learn about the findings in drug-gene studies to understand genetic variables and the potential reactions their patients may have to medications. Once doctors are aware of the benefit to patients, they must push to standardize drug-gene testing forcing hospitals and insurance companies to accept the practice.
Maron, Dina Fine. “The Right Pill For You,” Scientific American, October 2016, 47.