Purpose We aimed to study drug interactions and dose adjustments for renal impairment in
the discharge medication of surgical inpatients, and to evaluate strengths and limitations of
Clinical Decision Support software (CDSS) for this task.
Methods Cross-sectional study in 509 surgical patients of a primary care hospital. We
developed a customized interface for the CDSS MediQ, which we used for automated
retrospective identification of drug interactions in the patients’ discharge medication. Clinical
relevance of interactions was evaluated based on the Zurich Interaction System (ZHIAS) that
incorporates the Operational Classification of Drug Interactions (ORCA). Prescriptions were
further analyzed for recommended dose adjustments in patients with a GFR <60 ml/min.
Results In 509 patients with 2,729 prescriptions MediQ generated 2,558 interaction alerts
and 1,849 comments. Among those there were 10 “high danger” and 551 “average danger”
alerts that we reclassified according to ORCA criteria. This resulted in 10 contraindicated
combinations, 77 provisionally contraindicated combinations, 310 with a conditional and 164
with a minimal risk of adverse outcomes. The ZHIAS classification also provides categorical
information on expected adverse outcomes and management recommendations, which are
presented in detail. We identified 56 prescriptions without recommended dose adjustment for
impaired renal function.
Conclusions CDSS identified a large number of drug interactions in surgical discharge
medication, but according to ZHIAS criteria only a minor fraction appears to involve a
substantial risk. CDSS should aim at reducing over-alerting and improve usability in order to
become more efficacious regarding the prevention of adverse drug events in clinical practice.