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Genetic testing to guide antidepressant choices: Big news coverage, but limited evidence

Which antidepressant is right for you? This genetic test could help

Our Review Summary

depressionThis Philadelphia Inquirer article looks at two companies’ direct-to-consumer genetic tests designed to help doctors rely less on trial-and-error, and more on genetic markers, in guiding their medication choices for patients who’ve proven difficult to treat for depression.

The article offers balance through two patient anecdotes. One patient says the genetic testing helped guide her to an effective antidepressant, while the other isn’t convinced. An outside expert is also tapped who points to specific treatments rather than genetic testing for higher chances of success.

Although this article was cautious about the touted benefits, it would have served readers better by exploring some of the limitations of the research studies. The evidence doesn’t appear to come from gold-standard, randomized controlled trials. The only study we found through an online search was an abstract presented at a May 2018 medical conference.

 

Why This Matters

The majority of patients with major depression who choose antidepressant therapy do not achieve remission with the first medication they try. Even among those who do, many relapse. That’s why many patients end up frustrated — and still suffering with symptoms — as they endure a subsequent trial-and-error approach until an effective medication or combination of medications is found.

One promise of precision medicine — that has yet to be proven — is that genetic testing may help guide this process and make it more “personalized” and efficient. It’s important to make it clear (as this article does) that these genetic tests cannot predict which medicines will work, and it’s arguable if they can even identify those that will not.

Furthermore, because the financial stakes are high, it’s important for journalists to scrutinize (and be transparent) about the funding of studies on these genetic tests, potential conflicts of interest, and whether the results are expressed in more meaningful absolute terms, rather than more eye-catching (and potentially misleading) relative terms. For more on this, see our primer on evaluating relative vs. absolute numbers.

Criteria

Does the story adequately discuss the costs of the intervention?

Satisfactory

The article notes that the GeneSight test is covered by Medicare if a patient is being treated by a psychiatrist and that some insurance plans also cover the test. It also tells us that the Genomind Genecept Assay is covered by Medicare and Medicaid.

We aren’t provided out-of-pocket costs for the GeneSight test, though. Nor could we find the full price of Genomind’s ‘Genecept Assay’ on its website or elsewhere.

Does the story adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

On the one hand the article is appropriately cautious in stating:

But while genetic testing offers tools to better guide patients’ treatment, it cannot tell doctors which medicines will work — or necessarily provide the key to enduring remission from depression.

On the other hand, the results of Myriad’s recently published “large-scale test” on outcomes are given as “patients were 30 percent more likely to respond to treatment” when guided by their GeneSight test.

But, as we wrote back in May in a review of a Wall Street Journal article on the test, there’s problems with that percentage:

“No absolute numbers are given … just a relative improvement in ‘response’ to medication (ie. 30% greater response to the medicine when the test was applied).”

The Philadelphia Inquirer story quotes an independent source saying he’s impressed by the response rate (50%) and remission rate (40%) at six months, but again, these are relative numbers. Myriad did not provide the absolute numbers at 6 months … only at 8 weeks …. at which time the absolute difference in achieving remission between those who did and did not receive genetic testing was only 5%.

Does the story adequately explain/quantify the harms of the intervention?

Not Satisfactory

Although harms from a cheek swab are unlikely there is a potential harm in framing the genetic testing results as guiding the choice of one antidepressant over another. Patients may focus solely on pharmaceutical options, to the exclusion of non-pharmaceutical ones.

Antidepressants have well-documented side effects and drug interactions.

Does the story seem to grasp the quality of the evidence?

Not Satisfactory

The only data cited in the article comes from unpublished data presented at a medical conference. The research has not been peer-reviewed.

Does the story commit disease-mongering?

Satisfactory

No disease mongering.

We were glad to see the article include this relevant context:

As many as two-thirds of people with depression aren’t helped by the first antidepressants they try, leaving many to spend months after they are diagnosed without real help …. [genetic testing] is meant to help avoid the painful trial-and-error process many depression patients endure in the search for the right medicine.

Does the story use independent sources and identify conflicts of interest?

Not Satisfactory

As noted above, it should have been made clear that the May 2018 “large-scale test” is unpublished and funded by the test sponsor.

The same goes for the Genecept paper that is cited by the company’s VP: it’s an industry-sponsored review paper — not original research — and cannot  make claims about improved clinical outcomes or reduced overall medical costs from genetic testing.

We were pleased to see two independent sources cited, one of which provided a critical perspective.

Does the story compare the new approach with existing alternatives?

Satisfactory

An independent source is included who mentions transcranial magnetic stimulation (TMS) and electroconvulsivetherapy (ECT) as alternatives to antidepressants in the treatment of resistant depression.

One alternative that is not mentioned is cognitive behavioral therapy.

Does the story establish the availability of the treatment/test/product/procedure?

Satisfactory

It’s clear that both GeneSight from Myriad Genetics, and Genecept from Genomind, are commercially available.

Does the story establish the true novelty of the approach?

Satisfactory

By featuring both the work of Myriad Genetics and Genomind, the reporter makes it clear that this is already a competitive arena within so-called “precision medicine.”

Does the story appear to rely solely or largely on a news release?

Satisfactory

This article does not rely solely on a news release and quotes outside sources.

Total Score: 6 of 10 Satisfactory

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