Pharmacogenomic Testing Could Improve Depression Treatment

genomic Testing

According to new research from the University of British Columbia, a particular type of genetic test that helps determine the best antidepressant for patients with moderate-to-severe depression could generate significant healthcare savings and greatly improve patient outcomes.

The study found that pharmacogenomic testing might save the provincial public health system $956 million over the course of 20 years in British Columbia alone.

“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,”

said co-senior author Dr. Stirling Bryan (he/him), senior scientist at Vancouver Coastal Health Research Institute (VCHRI).

Response Variance Factor

One of the biggest burdens on public health is major depression, which affects one in ten Canadians at some time in their lives. In Canada, there are over 35 different antidepressant drugs available; nevertheless, approximately 27% of patients experience adverse effects and more than half of patients do not respond to the antidepressant that they are initially prescribed.

Previous studies have shown that up to 42% of the variation in how patients respond to these medications is due to genetic factors. Pharmacogenomic testing uses genetic information, typically obtained using a cheek swab, blood test or saliva sample, to help guide medication selection and dosing.

“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,”

co-senior author Dr. Jehannine Austin, professor of medical genetics and psychiatry at UBC, said.

Less Treatment-resistant Depression

The researchers collaborated with patients, doctors, and health system and government partners to create a simulation model that would mirror the experience of individuals suffering from major depression, from diagnosis to treatment, recurrence, and recovery. The model contrasted the anticipated journey of 194,149 persons with and without pharmacogenomic testing over a 20-year period by including B.C. health administrative data, clinical trial data, and defined treatment plans.

The model showed that pharmacogenomic testing would result in 37% fewer patients experiencing treatment-resistant depression, a situation in which the patients’ depression does not improve despite trying several kinds of treatment. Over the next 20 years, pharmacogenomic testing would result in patients spending 15% more time without depression symptoms, resulting in 1,869 fewer deaths and 21,346 fewer hospital admissions.

“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,”

said first author Dr. Shahzad Ghanbarian, a mathematical modeler and health economist at the Centre for Clinical Epidemiology and Evaluation, a research group within the VCHRI and affiliated with UBC.

Next Steps

The simulation model is intended to be flexible, and it could easily be extended to jurisdictions other than British Columbia, where it might be expected to find similar benefits, particularly in a comparable Canadian setting. Pharmacogenomic tests are not currently available through public health systems in Canada, but patients can pay for them through private companies.

The researchers say their findings support the inclusion of pharmacogenomic testing as part of normal, publicly-funded health treatment for persons with major depression in British Columbia, but further study is needed to identify how such testing could be implemented.

“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,”

said Dr. Bryan.


Background: Pharmacogenomic testing to identify variations in genes that influence metabolism of antidepressant medications can enhance efficacy and reduce adverse effects of pharmacotherapy for major depressive disorder. We sought to establish the cost-effectiveness of implementing pharmacogenomic testing to guide prescription of antidepressants.

Methods: We developed a discrete-time microsimulation model of care pathways for major depressive disorder in British Columbia, Canada, to evaluate the effectiveness and cost-effectiveness of pharmacogenomic testing from the public payer’s perspective over 20 years. The model included unique patient characteristics (e.g., metabolizer phenotypes) and used estimates derived from systematic reviews, analyses of administrative data (2015–2020) and expert judgment. We estimated incremental costs, life-years and quality-adjusted life-years (QALYs) for a representative cohort of patients with major depressive disorder in BC.

Results: Pharmacogenomic testing, if implemented in BC for adult patients with moderate–severe major depressive disorder, was predicted to save the health system $956 million ($4926 per patient) and bring health gains of 0.064 life-years and 0.381 QALYs per patient (12 436 life-years and 74 023 QALYs overall over 20 yr). These savings were mainly driven by slowing or avoiding the transition to refractory (treatment-resistant) depression. Pharmacogenomic-guided care was associated with 37% fewer patients with refractory depression over 20 years. Sensitivity analyses estimated that costs of pharmacogenomic testing would be offset within about 2 years of implementation.

Interpretation: Pharmacogenomic testing to guide antidepressant use was estimated to yield population health gains while substantially reducing health system costs. These findings suggest that pharmacogenomic testing offers health systems an opportunity for a major value-promoting investment.

  1. Shahzad Ghanbarian, Gavin W.K. Wong, Mary Bunka, Louisa Edwards, Sonya Cressman, Tania Conte, Morgan Price, Christian Schuetz, Linda Riches, Ginny Landry, David Erickson, Kim McGrail, Sandra Peterson, Rohit Vijh, Alison M. Hoens, Jehannine Austin and Stirling Bryan. Cost-effectiveness of pharmacogenomic-guided treatment for major depression. CMAJ Nov 2023, 195 (44) E1499-E1508; DOI: 10.1503/cmaj.221785