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Pharmacogenetic testing may improve drug treatments and shorten disability leaves

Veronika Litinski, MSc Medicinal Chemistry, MBA22 Sep 2021

This article by Antoine Lefaivre and Veronika Litinski of GeneYouIn, the company behind Pillcheck, and Maria Vandenhurk of Banyan Work Health Solutions, was published in Benefits Quarterly in the first quarter of 2017 under the title “Mental Health: Pharmacogenetic Testing May Improve Drug Treatments and Shorten Disability Leaves”. Below is a summary of the article, followed by what has changed since it was published.

Read the full article (PDF)

What does the article cover?

The article explains how pharmacogenetic (PGx) testing can benefit private health plans, benefits managers, health care providers and plan members. Everyone responds to medications differently, and genes that affect drug-metabolizing enzymes and transporters explain part of this difference. A PGx test combined with a medication review by a pharmacist trained in pharmacogenetics can help choose the right drug and dose, reduce side effects and improve adherence. Because DNA does not change, the results remain useful for future prescriptions.

What did the community pharmacy pilot find?

Two community pharmacies in Toronto offered PGx testing and medication reviews to 100 patients who took three or more medications or were starting a medication strongly affected by genes, such as an antidepressant, an opioid or clopidogrel. Most took part because a treatment was not working or was causing side effects.

Participants had an average age of 56.7 and took an average of 4.9 chronic medications, 2.0 of which had pharmacogenetic guidelines.
Pharmacists identified 175 drug therapy problems, or 1.75 per person, compared with 0.56 per person in a standard medication review. Of these problems, 68% were revealed by the PGx results.
The most common medications involved were antidepressants, statins, clopidogrel and proton pump inhibitors.
Pharmacists recommended switching the drug in 60% of cases, more monitoring in 22%, a dose change in 13% and stopping the drug in 4%.

How can PGx testing help in disability management?

The article notes that disability is the highest-risk part of a Canadian benefits plan and that mental health is a major driver of claims. Most of the cost comes from a minority of long cases, and the length of time away from work is a larger cost than the interventions themselves. Getting the medication right early makes other treatments, such as psychotherapy and rehabilitation, more effective.

The article describes a case study of a 27-year-old woman on long-term disability for anxiety and depression. Citalopram and sertraline had not worked and had caused dizziness and drowsiness. At her rehabilitation consultant’s suggestion, her insurer funded a PGx test. The results showed that she was an intermediate metabolizer, and the pharmacist’s report suggested that her side effects may have been caused by the medication building up in her body. Her psychiatrist restarted citalopram at a much lower dose and increased it slowly. Within a month her mood had improved and her side effects had decreased, and she returned to work about three and a half months after receiving her results.

What did the economic model show?

The article also presented an economic model for plan members starting antidepressants. These figures are projections from a model, not results measured in a trial:

Two years after starting treatment, 69% of people with PGx-guided treatment were projected to reach full remission, compared with 52% without it.
People with PGx testing were projected to need 78 days of absence over two years, 35 days fewer than the 113 days for those without testing, which the authors valued at about $7,000 in averted productivity loss.
A model using Canadian private plan drug claims estimated potential savings of 5% to 14% when PGx testing is used across several conditions.

What has changed since 2017?

A randomized trial followed the pilot. In a randomized trial in three Canadian community pharmacies published in 2021, people with depression or anxiety whose antidepressant treatment was guided by PGx testing had greater improvement in depression, anxiety and disability over six months than those who received standard treatment.
Stronger evidence for panel testing. In the large European PREPARE study of 6,944 patients, published in 2023, prescribing guided by a multi-gene pharmacogenetic panel lowered the odds of clinically relevant side effects by about 30%.
Genetic differences are even more common than thought. The article stated that 90% of people have a genetic variation affecting drug response. A 2021 analysis of nearly 490,000 people in the UK Biobank found that 99.5% carry at least one such variant.
Updated guidelines. The Clinical Pharmacogenetics Implementation Consortium (CPIC) updated its guideline for antidepressants in 2023, covering CYP2D6, CYP2C19 and other genes.
Broader coverage. Pillcheck now reports on 24 genes and 355 medications.

For current information on how pharmacogenetic testing can help shorten mental health disability claims, read 78% of mental health disability claimants are on the wrong medication. That’s a fixable problem.

How can a Pillcheck test help?

A Pillcheck test reports CYP2D6, CYP2C19 and other genes that affect antidepressants, pain medications, heart medications and many others. A pharmacist reviews each person’s results together with all their medications and prepares recommendations to share with their prescriber.

Pillcheck testing is performed in CAP- and COLA-accredited clinical genetic laboratories located in Canada. Pillcheck reports on 24 genes, increasing coverage with new guidelines and drug labels (see the genes tab), and covers 355 medications, which account for over 70% of dispensed prescriptions. The Pillcheck test panel ensures high accuracy for people of non-European and admixed ancestries. Your results last a lifetime, and report updates are free of charge.