(a) To explore the feasibility and utility of implementing broad preemptive pharmacogenomic result delivery in the inpatient setting across multiple institutions specifically with the goal of incorporating minority-specific pharmacogenomic information; (b) To determine whether clinical outcomes for the drug warfarin are improved in African Americans through the availability of pharmacogenomics-based dosing guidance at the point-of-care.

This study aims to determine whether preemptively obtained pharmacogenomic information can be delivered and utilized at the point-of-care across multiple institutions specifically in African American patients at risk for minority health disparities. The investigators have chosen the high-stakes, rapid-paced setting of inpatient medicine for this implementation study. The investigators seek to examine whether the availability of pharmacogenomic information improves prescribing.

The investigators will enroll adults at one of three institutions, The University of Chicago, University of Illinois at Chicago, and Northwestern University. During an initial (enrollment) hospital inpatient encounter, patients will be consented and a blood sample will be obtained for preemptive genotyping across a panel of actionable germline variants predicting drug response or toxicity risk. Patients will also be targeted for enrollment who are highly likely to initiate future warfarin therapy. Patients will be recruited to two primary cohorts. In the feasibility cohort, all patients will have their actionable pharmacogenomic results (with decision support) available to inpatient treating physicians for the duration of the study, once genotyping is completed, via the Genomic Prescribing System (GPS). Physicians and pharmacists will be individually approached for enrollment through a process of direct stakeholder engagement and informed consent. Participating providers will give permission for their medication decisions to be analyzed. Providers will never be instructed how to practice nor how to prescribe, and it is their choice whether or not to use GPS. GPS accession, use, and all medications prescribed throughout the admission will be passively recorded by the research team, for all patients, and an analysis of the impact of GPS results and decision-supports will be performed.

For the African American warfarin cohort, patients newly-starting warfarin will be enrolled at the time of new warfarin initiation and then randomized such that their treating physicians and pharmacists either have access to African American-specific warfarin dosing guidance via GPS, or not. The frequency of unfavorable (high-risk) scenarios related to warfarin-related clinical outcomes will be examined in each group.

Inclusion Criteria:

• Patients must be at least 18 years of age.
• Patients must self-identify as African American

Exclusion Criteria:

• Patients who have undergone, or are being actively considered for, liver or kidney transplantation.
• Patients with known active or prior leukemia.
• Inability to understand and give informed consent to participate.
• For patients being recruited to the warfarin sub-study, those with a glomerular filtration rate or creatinine clearance <30 mL/min34.

Adult patients will comprise the eligible patient population of this study. These patients will be identified through recruitment from the inpatient medicine services at each of the respective institutions, or from relevant clinics or clinical populations that are likely to initiate, or are newly-starting, warfarin therapy.