Table 4.

Summary of study characteristics for hospital admission theme.

Author (Year), Country	Study design and number of participants	Mean age of participants (years old)	Specialty and setting	Single-gene or panel test	CDST used	Genes tested	PGx test strategy	Pharmacist with reviewing role	Outcome measure: hospitalization/ED visits
Brixner et al. (2016), US	Prospective observational cohort study PGx-tested arm: 205 TAU arm: 820	PGx-guided arm: 75 TAU arm: 74	Cardiology, Primary care, and Internal Medicine Outpatient	Panel test	YouScript® system	CYP2C9, CYP2D6, CYP2C19, CYP3A4, CYP3A5, VKORC1	Polypharmacy patients currently or initiating on treatment with medication that has significant drug-gene interaction, were recruited to both arms of the study and only PGx tested in the PGx-tested arm.	Yes	At 4 months post-enrollment. Hospitalization rate: 9.8% of patients in the tested arm vs. 16.1% in the TAU arm. Relative risk = 0.61, p = 0.027 ED visits were 4.4% of patients in the tested arm vs. 15.4% in the untested arm. Relative risk = 0.29, p = 0.0002
Elliott et al. (2017), US	RCT PGx-tested arm: 57 TAU arm: 53	PGx-guided arm: 77 TAU arm: 75	Elderly care Home health agency	Panel test	YouScript® system	CYP2C9, CYP2D6, CYP2C19, CYP3A4, CYP3A5, VKORC1	Patients initiated with at least one medication with potential for significant drug-gene interaction were recruited to the study and randomized to the PGx-tested arm or TAU arm. Only patients in the PGx tested arm were PGx tested.	Yes	At 60 days post-discharge. The mean number of re-hospitalizations per patient was 0.33 (tested) vs. 0.7 (TAU). Relative risk = 0.48, p = 0.007 ED visits were 0.39 (tested) vs. 0.66 (TAU). Relative risk = 0.58, p = 0.045 Composite number of re-hospitalization and ED visits was 0.54 (tested) vs. 1.04 (TAU)
Epstein et al. (2010), US	Prospective Observational cohort study PGx-tested arm: 896 TAU arm (historical control): 2,688	PGx-guided arm: 65 TAU arm (historical control): 65	Anticoagulation Outpatient	Panel test	Not reported	CYP2C9 and VKORC1	Patients new to warfarin treatment were PGx tested and compared to a TAU arm that were not PGx tested.	No	Overall hospitalization-Hazard ratio = 0.69, p = 0.001 Hospitalizations for bleeding of thromboembolism- Hazard ratio = 0.72, p = 0.029
Perlis et al. (2018), US	Retrospective case control design PGx-tested arm: 817 TAU arm: 2,745	PGx-guided arm: 41 TAU arm: 39	Psychiatry Outpatients	Panel test	Not reported	Ten genes with only three reported- CYP2D6, CYP2C19, CYP3A4	Patients with a mood or anxiety disorder were PGx tested in the PGx-tested arm and compared to patients with the same diagnosis in the TAU arm that were not PGx tested.	Yes- pharmacist was available for additional interpretation if required by clinician	6-month follow-up period. The mean number of inpatient hospitalizations per patient is 0.07 (tested) vs. 0.17 (TAU). 57.9% difference. P < 0.0001 The mean number of inpatient hospitalizations for non-mood disorders is 0.05 (in tested patients) vs. 0.14 (in TAU patients). 65.5% difference. P < 0.0001 The mean number of ED visits is 0.19 (in tested patients) vs. 0.33 (in TAU patients). 40.4% difference. P < 0.0001
Ruaño et al. (2020), US	RCT PGx-tested arm: 1,459 TAU arm: 477	Median age 40	Psychiatry Psychiatric Hospital	Single-gene testing	Clinical Evaluation Monitoring System (CEMS) and Epic EMR	CYP2D6 (21 common variants	Patients with major depressive disorder were randomized to the PGx -guided arm where patients received PGx tests or TAU where patients did not receive PGx test.	No	Readmission rate within 30 days post-discharge is 10.1% (99/982) for tested patients and 9% (43/477) for patients receiving TAU.

PK, pharmacokinetics; PD, pharmacodynamics. Intervention arm is the group of participants that had PGx testing with the intention to receive PGx -guided drug therapy. TAU, treatment-as-usual arm. Number of participants are the number of participants allocated to both study arms (intervention and control group). Specialty and setting are the data sources. CDST, clinical decision support tool.