By Associate Professor Leslie Sheffield
There are now several pathology companies providing genetic testing for how people react to drugs.
There is a lot of difference in the way individuals handle medication and this can now be tested by a method called pharmacogenomic testing.
This type of testing is now available through doctors, selected pharmacists and even online together with a nominated doctor. The costs of these tests continue to come down as technology advances.
Despite all of this many doctors do not support this type of testing and some obstruct patients who are wishing to get tested. Why is this so? I will try and give you a short explanation of why this is so.
Firstly let me introduce myself. My Name is Dr. Leslie Sheffield and I am a Consultant Physician and Clinical Geneticist. I have served over 30 years as a clinical geneticist providing public genetic counseling services in South Australia and Victoria.
I established a private genetic interpretation and testing company in 2008 because the public service was not able to develop the field of pharmacogenomics and I felt there was enough evidence in 2009 that people in Australia should be able to make use of pharmacogenetics which was unavailable at the time.
I, therefore, raised money to start a private pharmacogenetics company and this company started to provide Australia-wide pathology testing in 2010 and has continued this service both here and overseas.
You might say that I am biased and have a conflict of interest because I am the director of a company that charges for these pharmacogenomic tests. My answer to this is although this is true I started the company and left a position in a public hospital because I believed these tests would be of benefit to people and they were not available in Australia at the time.
Furthermore, as mentioned above the tests are not very well known in the medical community so it is very difficult to support a business from the income, so my company has had to branch out to do other types of genetic testing.
Why is it so hard in some instances to get this type of test?
Firstly, it is relatively new and there are many other factors involved in drug prescribing so often it is overlooked.
Secondly, most doctors and pharmacists do not know the evidence associated with doing the test and the fact there are now official recommendations on dosage and drug choice given the results.
The first one was developed by the Pharmacogenetic Working Group of the Royal Dutch Association for the Advancement of Pharmacy (DPWG) and this has been incorporated into the National Dutch electronic prescribing system and so are available to every pharmacist and doctor together with the patient’s prescription record.
The second set of recommendations is by the Clinical Pharmacogenetics Implementation Consortium (CPIC). They have reviewed and evaluated the literature using clinical and pharmacokinetic studies on enzyme function, genetic tests and plasma levels of drugs.
The guidelines and recommendations for both DPWG and CPIC can be accessed at https://www.pharmgkb.org/guidelines.
Thirdly, many health professionals are unaware of the cost-benefit studies underlying these tests.
One of the randomized controlled trials mentioned above was a cost-benefit studies of patients on polypharmacy and the trial showed a cost saving of $US625 annually per patient.
Another study showed that patients who metabolize very slowly or too fast have 67% more medical visits and 4 times more disability claims than those with normal pharmacogenomic test results
The evidence base that pharmacogenomic testing works is growing rapidly and there are now 6 randomized trials that show that using a multiple gene pharmacogenetic test of the type available in Australia, improves the treatment of depression in guiding drug treatment 1-6. All these trials are very recent and there are at least 6 more being carried out at present.
The cost-benefit of pharmacogenetic treatment in mental illness has also been studied.
One of the randomized controlled trials mentioned above was a cost-benefit study of patients on polypharmacy and the trial showed a cost saving of $US625 annually per patient.
Another study showed that patients who metabolize very slowly or too fast have 67% more medical visits and 4 times more disability claims than those with normal pharmacogenomic test results.
In summary pharmacogenomic tests in the area of mental health have been shown to work by a growing body of scientific evidence and cost-benefit studies. There are now official guidelines that can be used to guide the results of these tests.
The tests can be accessed through doctors, specially trained pharmacists and online. Lists of pharmacies that have facilities for these tests can be found by inputting the postcode of residence into the pharmacy locator at www.mydna.life.
Tests can be ordered online at this site too. When ordering the tests through this site online or when doing it through a pharmacy a medical practitioner needs to be also nominated to receive the results. This means that both the doctor and pharmacist get the results to the benefit of the patient.
- Winner JG, Carhart JM, Altar CA, Allen JD, Dechairo BM. A prospective, randomized, double-blind study assessing the clinical impact of integrated pharmacogenomic testing for major depressive disorder. Discov Med. 2013;16(89):219-27.
- Singh AB. Improved Antidepressant Remission in Major Depression via a Pharmacokinetic Pathway Polygene Pharmacogenetic Report. Clin Psychopharmacol Neurosci. 2015;13(2):150-6.
- Perez V, Salvart A, Espadeler J, et. al. Efficacy of prospective pharmacogenetic testing in the treatment of major depressive disorder results of a randomized, double-blind clinical trial. BMC Psychiatry. 2017;17:250.
- Elliott LS, Henderson JC, Neradilek MB, Moyer NA, Ashcraft KC, Thirumaran RK. Clinical impact of pharmacogenetic profiling with a clinical decision support tool in polypharmacy home health patients: A prospective pilot randomized controlled trial. PLoS One. 2017;12(2):e0170905.
- Saldivar JS, Taylor D, Sugarman EA, Cullors A, Garces JA, Oades K, et al. Initial assessment of the benefits of implementing pharmacogenetics into the medical management of patients in a long-term care facility. Pharmacogenomics Pers Med. 2016;9:1-6.
- Bradley P, Shiekh M, Mehra V, et al: Improved efficacy with targeted pharmacogenetic-guided treatment of patients with depression and anxiety: a randomized clinical trial demonstrating clinical utility. J Psychiatr Res 2017; 96:100–10.
Study presented at American Psychiatric Association Annual Meeting; May 7, 2018; New York, NY. See https://shar.es/a1lEVa Not yet published.
https://www.apnews.com/b80bcb73f18a2d9495d6461166b79a96 include links to study results.
List of Studies Showing Cost-Benefit of Pharmacogenomic Testing
- Erik J. Groessl, Steven R. Tally, Naomi Hillery, Alejandra Maciel, Jorge A. Garces. Cost-Effectiveness of a Pharmacogenetic Test to Guide Treatment for Major Depressive Disorder J Manag Care Spec Pharm, 2018 Aug;24(8):726-734.
- Verbelen M, Weale ME, and Lewis CM. Cost-effectiveness of pharmacogenetic-guided treatment: are we there yet?. The pharmacogenomic journal 2017.17:,395-402.
- Maciei, A, Cullors, A, Garces J. Estimating cost savings of pharmacogenetic testing for depression in real-world clinical settings. Neuropsychiatric disease and treatment.2018:14 225-230.
- Joachim Benitez1, Christina L Cool*,2 & Dennis J Scotti. Use of combinatorial pharmacogenomic guidance in treating psychiatric disorders: financial impact on a health plan. Per.Med. (Epub ahead of print) ISSN 1741-0541 2018. Free at https://www.futuremedicine.com/doi/pdf/10.2217/pme-2018-0074.
- Joachim Benitez a, Michael R. Jablonski b, Josiah D. Allen b, Joel G. Winner. The clinical validity and utility of combinatorial pharmacogenomics:Enhancing patient outcomes. Applied & Translational Genomics 5 (2015) 47–49