VA Debates Who Should Receive Pharmacogenetic Testing

Deepak Voora, MD, director of VA’s Pharmacogenomics Action for Cancer Survivorship, provided an overview of PHASeR earlier this year at the National Press Club in Washington. VA photo

SALT LAKE CITY — A massive VA study revealed that 99% of veterans have at least one genetic mutation known to affect response to specific drugs, including some commonly prescribed antidepressants, anticoagulants, antivirals, oncology medications and statins. That raises the question of who should be tested for which variants and when, which has stirred lively debate within the VA.1

Nearly 55% of the 7,769,356 veterans in the study took one of the drugs with strong evidence of interaction with a specific gene mutation over the six year period analyzed. More than one-third of veterans received a new prescription for one of these drug and, of those, 38% were prescribed more than one drug for which genetic information could guide use, dosage, and expected response within one year.

“Based on those key findings, if broad pharmacogenetic testing (PGx) were implemented, incorporating this information into prescribing decisions would impact a large proportion of veterans,” said the study’s lead author Catherine Chanfreau-Coffinier, PhD, research health scientist at VA Informatics Computing Infrastructure at Salt Lake City Health Care System.

In the categorization developed by the Clinical Pharmacogenetics Implementation Consortium, medications with known gene/drug interactions that affect prescribing are classified as level A drugs. The category includes nearly 60 drugs such as simvastatin, tramadol, warfarin, clopidogrel, codeine, citalopram, abacavir and amitriptyline.

The VA study focused on use of 30 level A drugs for which CPIC recommended prescribing an alternative medication or adjusting the dose based on genetic findings.

For some of the drugs, knowing if a veteran has a specific genetic mutation could be life altering.

“The right timing depends on the outcome you’re trying to prevent or enhance,” said study co-author Sony Tuteja, PharmD, of the Corporal Michael Crescenz VAMC in Philadelphia. “To avoid life-threatening reactions, you need to test before the first dose.”

Continue Reading: