Monday, April 7, 2008

Pharmacogenetic Testing Companies under Fire

Individualized testing for medication response should improve medical care, but according to a critique from the Johns Hopkins University Genetics and Public Policy Center, pharmacogenetic testing (the study of genes that determine drug behavior) may be misleading physicians and health care consumers.

Currently, more than 15 companies offer CYP450 testing to guide physicians in prescribing SSRI’s (antidepressants), yet the Centers for Disease Control and Prevention uncovered "no evidence...that the results of CYP450 testing influenced SSRI choice or dose and improved patient outcomes.". Biomarkers that identify individual response to medication and treatment may sound good, but only a few are actually proven, leading to the criticism.

The viewpoint from John Hopkins stems from the fact that the physician is left out of the picture. Pharmacogenetic testing is available directly to consumers, a problem that may lead patients to request certain medications, again bypassing the function of the doctor. In addition, marketing claims vary with each company and are currently unregulated.

The authors of the critique feel that the FDA should intervene to protect the public from these companies. They also suggest that a public registry be maintained for tracking purposes regarding test usage. Further recommendations include intervention from the Federal Trade Commission to prevent false advertising.

Pharmacogenetic testing is offered to identify the metabolism of medications such as warfarin, opiates, beta-blockers and antiarrhythmic medications. Testing companies claim that pharmagogenetic analysis is a better option than “trial and error”, minimizing the liability of the physician and patient risk of medication side effects. Other claims for “individualized care”, and “practice building” are seen in the marketing ads, all of which sound appealing.

The conclusions are that genetic testing may not improve medical care or encourage public trust in genomic medicine in the absence of supportive clinical data.

Science. 2008;320:53–54. ◦