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

Abstract

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.