Genetic profiling could identify which antidepressants work best for patients

Genetic testing can show which antidepressants are most likely to be effective for a particular individual, according to a new study from Canada.

Up to 42% of the variation in how patients respond to antidepressants is the result of genetic factors, but currently finding out which antidepressant works for which patient is a matter of trial and error.

The study investigated the potential of pharmacogenomic testing, which uses genetic information, typically obtained using a cheek swab, blood test or saliva sample, to help guide medication selection and dosing. The findings were published in the Canadian Medical Association Journal.

Researchers from the University of British Columbia worked with patients, clinicians and health system partners to develop a simulation model that mimics the experience of patients with major depression, from diagnosis through to treatment, recurrence and recovery.

The model, which incorporated provincial health administrative data, clinical trial data and defined treatment strategies, compared the projected journey of 194,149 adults with and without pharmacogenomic testing over a 20-year period.

Costs to health systems would be reduced

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 types of treatment, the model found.

It would also lead to patients spending 15% more time without depression symptoms, resulting in 1,869 fewer deaths and 21,346 fewer hospital admissions over a 20-year period. Costs to health systems would be reduced by eliminating the need for patients to try out different drugs before finding the right one.

Dr Stirling Bryan, professor at the University of British Columbia’s school of population and public health and co-author on the study, 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.”

He added that the benefits to patients “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.”

Dr Jehannine Austin, professor of medical genetics and psychiatry at the University of British Columbia and also co-author, 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.”

First author Dr Shahzad Ghanbarian, a mathematical modeller and health economist at the Vancouver Coastal Health Research Institute, 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, one of the patient partners on the study, 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.”

The researchers said that their findings make a strong case for including pharmacogenomic testing as part of routine, publicly-funded healthcare for people with major depression. 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.”