Implementation of Pharmacogenetic Testing Within the Veterans Health Administration From 2011 to 2013

We assessed implementation of precision medicine within the Veterans Health Administration. We analyzed the use of interleukin-28B (IL28B) pharmacogenetic test, which predicts interferon-α treatment response in patients with hepatitis C. Patients with favorable CC genotype exhibit a two-fold higher response than patients with less favorable genotypes (CT and TT). Linking IL28B tests to Veterans Health Administration clinical data, we analyzed test use, concordance with guidelines, subsequent interferon-α treatment, and site variations. From January 2011 until December 2013, 3,529 Veterans underwent IL28B testing. There were 2,988 (85%) tests linked to electronic health record data. Demographics in those with clinical data: 97% male, mean age 59 years (SD 6.8), race: White 50%, Black 43%, Hispanic 3%, and other 3%. In Whites, the favorable CC genotype was three-fold more prevalent (541, 36%) than in Blacks (151, 12%). Analysis of IL28B timing revealed 2,373 (79%) Veterans were appropriately tested before interferon-α, 49 (2%) tested concurrent with interferon-α, and 566 (19%) tested post interferon-α treatment. Of the 630 treatment-naïve Veterans with CC genotype, only 144 (23%) initiated interferon-α treatment post-testing. Although 35% of IL28B tests overall did not influence care, the majority of tests were guideline concordant and clinically useful. IL28B testing varied substantially by site and state.