Potential clinical impact of medication discrepancies at hospital admission.

Background: Medication errors at the interfaces of care are highly prevalent. This study aims to identify unintentional medication discrepancies at hospital admission and to explore their potential clinical impact in elderly patients.

Method: The study was conducted in an Internal Medicine Department. Patients ≥ 65 years admitted through the emergency department were eligible. Best possible medication histories, obtained from different sources by pharmacists, were compared to admission medication prescriptions to identify and correct unintentional discrepancies. A three-category scale was used to rate errors for their potential to cause harm: Level (L) 1 "no potential harm", L2 "monitoring or intervention potentially required to preclude harm", and L3 "potential harm". This scale was also designed to take into account patient's clinical characteristics and high-risk drugs.

Results: 256 patients were included. Mean age was 82.2 ± 7.2 years old. 85 patients (33.2%) had ≥ 1 unintentional discrepancies. Overall, there were 173 unintentional discrepancies. The 3 most common drug classes involved in errors were nervous system (22.0%), gastrointestinal (20.0%) and cardiovascular (18.0%) medications. The most common types of errors were "omission" (87.9%) and "incorrect dose" (8.1%). Among the unintentional discrepancies, 20.8% had the potential to require increased monitoring or intervention to preclude harm (L2) and 6.4% had the potential to cause clinical deterioration (L3).

Conclusion: More than 25% of the identified errors presented a potential clinical impact. These results show that a combined intervention of pharmacists and physicians in a collaborative medication reconciliation process has a high potential to reduce clinical relevant errors at hospital admission.