Inconsistent Reporting of Interactions Between Warfarin and Medicinal Plants Across Clinical Decision Support Resources

Background: Warfarin, a commonly used anticoagulant, interacts with medicinal plants, potentially complicating patient management. Clinical Decision Resources (CDRs) provide guidance on these interactions, but inconsistencies across resources may impact clinical decisions. This study aims to evaluate the consistency of interaction reports between warfarin and medicinal plants across four online CDRs. Methods: A cross-sectional study was conducted. Medicinal plants assessed were selected from the World Health Organization's Phytotherapy Manual. Interaction reports were manually reviewed across four CDRs: UpToDate, ClinicalKey, DynaMed, and DrugBank. Interactions were categorized by severity as mild, moderate or severe. Results: Of 141 medicinal plants reviewed, 28 were documented as interacting with warfarin in at least one of the four assessed CDRs. DynaMed reported interactions for 18 plants, ClinicalKey for 15, UpToDate for 13, and DrugBank for 3. Only one plant (Ginseng - Panax ginseng) was consistently identified across all CDRs, although discrepancies in the direction of the interaction (whether it increased or decreased anticoagulant effect) were observed. Regarding interaction severity classifications, there was substantial variability, with ClinicalKey identifying the highest proportion of severe interactions (32.1%). Conclusion: We identified significant variability among CDRs in reporting interactions between warfarin and medicinal plants, which may lead to inconsistencies in clinical decision-making. To ensure more consistent and reliable patient care, standardized and comprehensive methodologies for assessing these interactions are needed.