Background Medication errors, specifically the lack of continuity of the patient’s usual treatment, are a major cause of adverse effects in hospitalised patients, most of them preventable. Medicines reconciliation is the process of comparing a patient’s prescriptions for medicines to all the medicines the patient has been taking.

Purpose To analyse the impact of reconciliation in different clinical services depending on discrepancies identified and severity of medicines errors (MEs).

Materials and Methods Retrospective, descriptive study conducted at a general hospital over 6 months. Daily, we identified newly-hospitalised patients aged over 75. To determine that a discrepancy existed, we compared the patient’s usual medicines with the prescribed medicines and interviewed patient and/or carers. For each service, we collected: number of patients reconciled, number of drugs evaluated, kinds of discrepancies according to Documento de consenso sobre terminología, clasificación y evaluación de los programas de Conciliación de la Medicación, and severity of MEs identified according to National Coordinating Council for Medication Error Reporting and Prevention.

Results Reconciliation was conducted in 13 clinical services. 558 patients were reconciled (mean age: 83.86). 56% belonged to Internal Medicine (IM), followed by General Surgery (GS) (18%) and Traumatology (13%). 9.33 drugs were evaluated per patient, higher than average numbers of prescribed drugs being found in Ophthalmology (18), Cardiology (17.48), IM (11.62), Pneumology (11.29) and Oncology (10.38). We detected 1140 discrepancies. The services with more discrepancies requiring clarification (n = 412) were: IM (51%), GS (16%) and Traumatology (12%). The services with the highest rates of MEs were Traumatology (60%), Otolaryngology (60%), Pneumology (59%), Urology (57%) and Haematology (50%), while unresolved discrepancies were noted in Gynaecology (78%), Oncology (64%), GS (51%) and Ophthalmology (50%). Most MEs fell into category C (errors that reached patient but did not cause damage) severity but 1% were category E (error that resulted in temporary harm and required an intervention). The omission of a medicine was the most common unjustified discrepancy.

Conclusions Medicines reconciliation is important in IM, GS and Traumatology because of numerous discrepancies requiring clarification, the proportion of patients and, mainly in IM, the amount of drugs for chronic treatment. The role of reconciliation was judged essential in clinical services with more MEs (Traumatology, Otolaryngology). Unresolved discrepancies pose a potential cause of ME, so in Gynaecology and Oncology we should improve communication with clinical teams to encourage patient safety.

No conflict of interest.