Prescription patterns of outpatients and the potential of multiplexed pharmacogenomic testing

Abstract

Background: Pre-emptive pharmacogenomic (PGx) testing is potentially an efficient approach to improve drug safety and efficacy but the target population to test is unclear. Objectives: We aim to describe the prescription pattern of PGx drugs among adult medical outpatients. Methods: We estimated the 5-year cumulative incidence (CI) for receiving three groups of PGx drugs using competing risks analysis: (i) all PGx drugs, (ii) PGx drugs with guidelines and (iii) PGx drugs with serious clinical effects. Comparisons of CIs were also done by patient characteristics using Gray's test. Results: The 5-year CIs of receiving any new PGx drug, PGx drug with guidelines and serious clinical effects were 42.6%, 37.3% and 13.7%, respectively. The 5-year CI of receiving any new PGx drug was higher for patients >40 years old (43.6% vs ≤40 years old 36.0%, P < 2.2 × 10−22), Malays and Indians (50.3% and 49.8% vs Chinese 31.1%, P < 2.2 × 10−22), those who attended one of the following four specialties at the index visit compared to other specialties (infectious diseases [46.2% vs 42.6%, P = 2.9 × 10−4], psychiatry [48.3% vs 42.3%, P = 7.4 × 10−13], renal [49.8% vs 40.9%, P < 2.2 × 10−22], and rheumatology and immunology [54.8% vs 41.7%, P < 2.2 × 10−22]) and those prescribed ≥5 drugs at index visit (51.7% vs 0-4 drugs 41.7%, P < 2.2 × 10−22). Conclusions: Medical outpatients have a substantial probability of benefiting from pre-emptive PGx testing and this is higher in certain subgroups of patients.