Background The medication reconciliation (MR) is a key point to increase patient safety that allows to detect medication errors, called discrepancies. MR at hospital admission consists in comparing the patient's usual treatment with intrahospital prescription.

Purpose To measure the incidence of medical error in the admission process in our hospital in internal medicine service (third level hospital). Solve possible unintended discrepancies to assess the need to implement a MR process into the clinical practice.

Materials and methods Observational and interventional pilot study in September 2011. The pharmacological history was obtained from patient history completed with an interview, and then compared to the prescription of the hospital within 24 h of admission. Discrepancies were recorded and classified as justified or not justified, and these were reported to the prescriber by written notice and then classified as intentional or non-intentional (medication error, ME).

Results 71 patients from 126 admitted in the service were included. The mean age of the patients was 79.6 years old, 53.7% were women. The authors reconciled 616 drugs, with an average of 8.68 drugs/patient (SD 3.75) at admission. Pharmacist detected 112 discrepancies not justified which 43 was ME in 26 patients (omission, discrepancies on dosage or frequency, extra medicine ‘unnecessary’, different drug). That represents a rate of 36.6% patients with ME and the 6.9% of drugs reconciliated. The pharmaceutical interventions in reconciliation were accepted by physicians in 23 cases (53.5%). The average of drugs in patients with ME were 9.9 and in those without 8 (p<0.038).

Conclusions An important number of patients have a ME, particularly those with a higher number of drugs. Despite half pharmaceutical interventions were accepted, the authors must design a MR record file to make the intervention easier and improve patient safety at admission. To develop the MR in the patient with more incidence of ME in all the services, we will need a full-time pharmacist.