Woman sitting in front of laptop with head in hands to illustrate depression
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A genetic test that helps determine the best medication for patients with moderate-to-severe depression could generate substantive health system savings and greatly improve patient outcomes, according to new research from the University of British Columbia (UBC).

The study, published in the Canadian Medical Association Journal (CMAJ), estimates that in British Columbia (B.C.) alone, implementing pharmacogenomic testing could save the public health system an estimated $956 million over 20 years.

“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,” said co-senior author Stirling Bryan, professor at UBC’s school of population and public health, and senior scientist at Vancouver Coastal Health Research Institute (VCHRI).

He added, “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.”

The researchers report that 1 in 10 Canadians will experience major depression at some point in their lives, making it one of the largest public health burdens. While more than 35 antidepressant medications are available in Canada, over half of patients don’t respond to the antidepressant they are initially prescribed and roughly 27% report adverse effects.

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 can guide medication selection and dosing.

“Genes play an important role in how our bodies metabolize different antidepressants, which ultimately influences their efficacy,” said co-senior author Jehannine Austin, professor of medical genetics and psychiatry at UBC. “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.”

For this 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 B.C. 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% fewer patients experiencing treatment-resistant depression, a situation in which the patients’ depression does not improve despite trying several kinds of treatment. Pharmacogenomic testing would also result in patients spending 15% more time without depression symptoms, resulting in an anticipated 1,869 fewer deaths and 21,346 fewer hospital admissions over 20 years.

“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,” said Shahzad Ghanbarian, a mathematical modeler and health economist at the Centre for Clinical Epidemiology and Evaluation, a research group within the VCHRI.

Pharmacogenomic tests are not currently offered through the public health systems across Canada, but patients can pay for them through private companies.

The researchers say their analysis makes a strong case for including pharmacogenomic testing as part of routine, publicly-funded health care for people with major depression in B.C., but more work is needed to determine how such testing could be put into practice.

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