A special kind of genetic test that helps determine the best antidepressant for patients with moderate-to-severe depression could generate substantive health system savings and greatly improve patient outcomes, according to new research from Canada.
The study, published today in CMAJ, shows that in British Columbia. alone, implementing pharmacogenomic testing could save the provincial public health system an estimated $956 million (£562 million) over 20 years.
Co-senior author Dr Stirling Bryan is professor at the University of British Columbia’s school of population and public health, and senior scientist at Vancouver Coastal Health Research Institute (VCHRI).
He said: “Pharmacogenomic testing aims to match patients with medications that are more likely to be effective and cause less side effects, based on their genetic profile.
“Our findings show that the benefit to patients in B.C. could be enormous, including increased remission rates and better quality of life, while generating significant cost savings by keeping people out of hospitals and more intensive treatment pathways.”
One in 10 Canadians will experience major depression at some point in their lives, making it one of the nation’s largest public health burdens.
While more than 35 antidepressant medications are available in the country, over half of patients don’t respond to the antidepressant they are initially prescribed and roughly 27 per cent report adverse effects.
Previous studies have shown that up to 42 per cent of the variation in how patients respond to these antidepressants is due to genetic factors.
Pharmacogenomic testing utilises genetic information, typically obtained using a cheek swab, blood test or saliva sample, to help guide medication selection and dosing.
Co-senior author Dr Jehannine Austin, professor of medical genetics and psychiatry at UBC, said: “Genes play an important role in how our bodies metabolize different antidepressants, which ultimately influences their efficacy.
“The genetic insights provided by pharmacogenomic testing can help physicians make more informed treatment decisions and reduce the lengthy trial-and-error process that many patients experience in finding an effective medication.”
In the study, the researchers worked with patient partners, clinicians and health system and government partners to develop a simulation model that mimics the experience of patients with major depression, from diagnosis through to treatment, recurrence and recovery.
By incorporating provincial health administrative data, clinical trial data and defined treatment strategies, the model compared the projected journey of 194,149 adults with and without pharmacogenomic testing over a 20-year period.
The model showed that pharmacogenomic testing would result in 37 per cent fewer patients experiencing treatment-resistant depression, a situation in which the patients’ depression does not improve despite trying several types of treatment.
Pharmacogenomic testing would also result in patients spending 15 per cent more time without depression symptoms, resulting in an anticipated 1,869 fewer deaths and 21,346 fewer hospital admissions over a 20-year period.
First author Dr. Shahzad Ghanbarian is a mathematical modeler and health economist at the Centre for Clinical Epidemiology and Evaluation, a research group within the VCHRI and affiliated with UBC.
The researcher said: “By incorporating the perspectives of patients with lived and living experience into this model, alongside robust data sets, we are able to carefully simulate the treatment journey of people with major depression.
“The simulation model is designed to be flexible and could be applied to other jurisdictions beyond B.C., where we might expect to see similar benefits, particularly within a comparable Canadian context.”
Linda Riches lives in Salmon Valley, B.C., and has been living with major depression for over 30 years.
Riches was one of the patient partners who helped undertake the study.
She said: “All people with major depression deserve to feel hopeful about their life.
“Genetic testing may give them the opportunity to know what treatment they need, not the 10 they didn’t need.”
Pharmacogenomic tests are not currently offered through the public health systems across Canada, but patients can pay for them privately.
The researchers say their analysis makes a strong case for including pharmacogenomic testing as part of routine, publicly-funded healthcare for people with major depression in B.C., but more work is needed to determine how such testing could be put into practice.
Dr Bryan said: “We’ve shown here this can be effective, and our next step is to figure out the best way to do it, with input from patients, physicians, government and health sector partners.
“Exploration of implementation strategies, such as which health-care professionals are best-suited to deliver pharmacogenomic testing, is the natural next step and remains unexplored in Canada.”
