Why Genetic Testing Is Key to Advancing Precision Medicine

September 13, 2021 - Due to genetics, not every patient responds the same to medications. With genetic testing, providers can better determine the best treatment options for individuals, advancing precision medicine. 

Jacob Johnson, MD, a practicing otolaryngologist and president of San Francisco Otolaryngology, spoke with HealthITAnalytics about the importance of genetic testing in senior populations and the role associated with genetics in medication relations.

"The medications we take are primarily metabolized by our kidney and our liver by a set of genetically-determined enzymes," Johnson said.

Depending on the patient's genes, the enzymes could have low, medium, high functions, leading to different metabolizing rates. According to Johnson, these differing rates create problems for physicians when trying to prescribe medications.

Many physicians will assign the same doses to everyone unless their records indicate something different. Factors such as gender, race, ethnicity, and other medications can be overlooked when determining patient dosages.

Among senior populations, Johnson advocated for a personalized medicine approach that tests a patient's genetics to improve health outcomes. According to the Health Policy Institute, the senior population fills an annual average of 20 prescriptions per person, making polypharmacy common in senior populations.

"Polypharmacy is when someone takes more than four or five medications, or they're taking multiple medications for the same problem," Johnson explained.

With polypharmacy, medications can cross-interact with each other, potentially creating new medical complications for patients. Additionally, it becomes more difficult for clinicians to keep track of all the issues. Polypharmacy could negatively impact patient care without understanding a patient's genetics and the metabolic levels of medications.

Failing to analyze a patient's genes through polypharmacy genetic testing could have a major impact on a patient's health. Johnson highlighted the several risks associated with skipping the tests on senior populations, including struggling to determine drug doses, questioning how multiple medications interact, and facing difficulties in producing the desired treatment results.

Everyone's body responds differently to medication, and without genetic testing, it's difficult to predict the outcome. Additionally, Johnson identified another risk factor is how people age.

"The other part that's challenging about becoming older is that a lot of our sensory systems get degraded — vision, touch, smell, taste, hearing, balance. So, a person's already vulnerable as they get older for assessing their environment and reacting to it. One of the most common side effects of medications is they make you a little drowsy, agitated, not focused, or off-balance," Johnson continued.

"When we have patients coming in and they complain of dizziness or falls, we evaluate their balance system and test their vision. We realized that if someone's on ten medicines, it was very challenging to assess the risk of each medicine"

Johnson explained that often when a senior shows up at urgent care of the emergency, it is related to issues with their medication, creating a considerable burden on the healthcare system. By conducting genetic testing, providers can strive for precision and personalized medicine to find the root of the problem.

According to Johnson, safety and quality concerns are likely to arise from failing to address pharmacogenetic factors. He gave the example of if a person falls, providers will want to make sure they don't fall again.

The patient will take part in fall safety programs while they are in the hospital but then will be sent home with medications that give them low blood pressure or have side effects such as drowsiness.

"The quality has to extend throughout that care spectrum. When I do surgery, the surgery is from the moment I see you to years from now where the full outcome of my surgery is," Johnson explained.

"At 30 days, most patients say they’re better. But are you better in four or five years? With medication, we don't think in those same terms. We just prescribe and keep prescribing without measuring the output at the end. If a medication doesn't work for you or we don't know the correct dosing, we shouldn't give it to you."

As healthcare continues to move towards an era of precision medicine, providers should be conducting genetic testing to identify the best treatment options for the patient.