Wouldn’t it be great if there were some sort of test you could take to predict which medications are most likely to work best for you personally, and which ones could hurt you with an adverse reaction? Good news: There is such a test, and although you probably haven’t heard of it, it’s not some out-of-reach possibility for future use – it’s starting to pop up at medical centers around the country.
Just as your genes determine traits like eye color and whether you have dimples or freckles, they also influence the way each individual reacts to medications. That’s one big reason that a particular drug might work well and cause no problems for one person, might not have any helpful effect in another person, and pose a life-threatening risk to someone else.
The drug-response test known as PGx (pharmacogenetic) testing uses a small sample of a patient’s blood or saliva to look for genetic differences in their DNA that could show whether a drug is likely to be effective, whether it is likely to cause side effects, and what the best dose is for that person.
What PGx Tests Are – And Are Not
There are different PGx tests, depending on the medicine. Here is a list of PGx tests from the Mayo Clinic, along with the medicines for which they test. p Not every drug has a PGx test, and no OTC drugs have PGx tests.
There are limits — a “normal” PGx test result doesn’t guarantee you aren’t at risk for an adverse event or that the drug is ineffective for you. Current tests only capture the variants we know about now. Future tests will certainly improve and add more genes.
Though PGx testing is already available in some places, it isn’t yet widespread, and insurance coverage is still limited. “Drugs that are known to work differently based on a person’s genetics are likely to be covered – for example, clopidogrel, warfarin, fluoxetine, simvastatin and abacavir,” explains Mohamed A. Jalloh, PharmD, assistant professor at Touro University California College of Pharmacy and spokesman for the American Pharmacists Association.
Does Medicare Cover It?
Medicare does pay for the test, but commercial insurers are taking it slower. “PGx testing is an emerging field, so many insurance plans have not started covering it,” notes Dr. Jalloh. In a recent analysis, only 3 of 65 health insurance policies reviewed were found to cover PGx testing.
And plans that do cover it are likely to do so only when it’s deemed medically necessary, rather than for any patient who is interested in being tested. (As an example, this is Cigna’s policy. [pdf]) That may change as awareness about the test continues to grow, especially since a recent study found that 1 in 4 patients has a drug-gene association that poses a serious risk.
Because PGx tests your DNA, some might worry about privacy issues. Be assured that federal law 31 “prohibits any use of genetic information by health insurers and employers, though other groups may still use this information (eg, life insurers and the military).”
Here are 5 more things you should know about PGx testing:
1. It is likely that the results of taking the test one time will be useful for drugs in the future. Many commonly prescribed drugs interact with only a small number of genes. For that reason, taking the test once might cover you for drugs you need in the future. Therefore, make sure you or your healthcare providers are sharing the results with all of your doctors and your pharmacist.
2. The test itself takes 2 minutes, but it can take anywhere from 5 to 14 days for a lab to process it and provide results. “Certain medications may be started in the meantime to avoid the risks of treatment delays,” says Dr Jalloh.
3. The testing covers over 330 commercial drugs, including all FDA “black-box” drugs – about 155 or so – for which the test is required or highly recommended, according to Sternfeld. These medications have been linked with serious or life-threatening side effects. (https://www.fda.gov/downloads/forconsumers/consumerupdates/ucm107976.pdf)
4. “There is also a huge savings in patient healthcare costs as it eliminates trial-and-error prescribing plus the costs of hospitalizations for adverse events,” Sternfeld says.
5. Certain medical centers are more likely to offer testing than others. University hospitals affiliated with PhD programs that focus on pharmacogenomics are likely to offer the testing. “Also, some pharmacy schools are leading the way in research and training – for example, the University of Colorado Skaggs School of Pharmacy and the College of Nursing has a pharmacogenetic training program, therefore hospitals or clinics affiliated with the school may be possible choices for testing,” states Dr. Jalloh. (h)
What to Ask Your Doctor
In general, patients should ask their pharmacist if any of their current medications may work differently based on one’s genetic makeup, Dr. Jalloh suggests. “Patients should ask for this evaluation anytime their pharmacist does a comprehensive medication review or medication check-up.”