AHRQ’s Evidence Report on Depression, CYP450 Testing for Adults Treated with SSRIs concluded “There is a paucity of good-quality data addressing the questions of whether testing for CYP450 polymorphisms in adults entering SSRI treatment for non-psychotic depression leads to improvement in outcomes, or whether testing results are useful in medical, personal, or public health decisionmaking.”

Last week, a reporter from the Wall Street Journal asked for my response. Here is what I said:

This study essentially only states that there are not randomized trials proving that CYP testing will improve outcomes nor are there studies that prove that they do not improve outcomes. It also states that FDA approval and clinical use for new genetic testing technologies should be based on test accuracy rather than on demonstration of improved clinical outcomes. Genelex agrees that these trials are important and should be done, but there is no reason to not have testing available in the interim.

* Hospitalized psychiatric patients who are poor metabolizers cost $4,000 – $6,000 more in medical care compared to patients with an average metabolizer genotype. All antidepressants and antipsychotic medicines are processed by enzymes with a high incidence of poor metabolizers. Journal of Clinical Psycopharmacology 20:246 2000

* Fifty-nine percent of drugs most commonly cited in ADR studies are processed by enzymes with genes known to have poor metabolizer variants. This is compared to 7% of a random selection of the top selling drugs. (JAMA 286:2270 2001).

* Multiple studies including the Kircheiner review have found that people with CYP variants require lower doses of the affected medications.

Although randomized trials are not completed yet, they are in progress, and these facts are very telling. Clinicians and patients should have access to this information if they want it. It is doubtful a physician would prescribe without knowing the patient’s age, sex, and medical history – if the CYP genetics are available they should use that information too. The trend in psychiatry is utilizing polypharmacy to treat psychiatric conditions, and many of these patients have co-morbid conditions for which they are also receiving drugs. The complexity of these medication regimens heightens the need for DNA testing and the use of interpretive software as a step toward personalized medication management. In essence, I agree with this quote from John Concato, MD (Director, VA Clinical Epidemiology Research Center, Yale University) – “Putting what we know into practice would prevent more disease than worshiping at the altar of randomized trials.”

Filed under: Cytochrome P450, Personalized Medicine, Pharmacogenetics Tagged: | DNA, Personalized Medicine, Pharmacogenetics