Background Medicines reconciliation studies have produced estimates about rates of patients and drugs involved in unintended discrepancies along the reconciliation process, but to our knowledge no-one has worked out the reasons for these discrepancies.

Purpose To determine and analyse the prevalence of unintended discrepancies in medicines reconciliation at our Emergency Department (ED), in which a Hospital Pharmacist is integrated into a multidisciplinary team.

• To find out the main reasons that justify intended medicines discrepancies.

• To analyse the ATC groups of drugs mostly involved in unintended discrepancies.

Materials and methods Prospective non-interventional study conducted by a fourth-year resident pharmacist from 1–31 May 2012 at the Hospital ED.

In the study we included all patients admitted to the ED from 08:00 to 11:30 am, Monday to Friday. Information regarding the patient’s previous medicines was collected from primary healthcare databases, records of previous hospital discharges and recent medical reports, followed by an interview with the patient or caregiver.

All this information was compared with drug prescription in the computerised prescription order entry (CPOE) system introduced by the ED physician. No discrepancy was considered if a home drug was prescribed with same dose, frequency and route in CPOE. Medicines discrepancies were classified as intended (if the drug was tailored to the clinical situation) or otherwise unintended, after consensus with the attending ED physician. Data were analysed with SPSS v.15.

Results We analysed 1,138 home drug prescriptions in 117 patients, resulting in 76.3% of discrepancies, of which 85.6% were intended and 14.4% unintended. Unintended medicines discrepancies affected 55.6% of patients.

The reasons recorded for intended discrepancies were: PRN medicines (17.9%), limited oral tolerance and drug not essential in treatment of an acute pathology (15.8%), change according to clinical practice guidelines (14.8%), adaptation of dose and/or frequency to current patient situation (12.4%), oral intolerance (11.3%), medicines not indicated in the current situation (7.5%), change of drug because not available in hospital (6.1%) and others (14.2%).

The ATC groups showing higher rates of unintended discrepancies were: B (22.5%), N (19.1%), C (15.7%), A (6.7%) and R (4.8%), with statistically significant differences (p < 0.001).

Conclusions Most discrepancies found were intentional and justified as adaptations of previous home medicines to the acute process. The rate of unintended discrepancies found by clinical pharmacist was 14.4%. This allowed a better medicines reconciliation made by the hospital pharmacist integrated in the ED interdisciplinary team regarding unintended discrepancies.- The most frequent ATC of drugs affected by unintended discrepancies were: Blood and blood-forming organs (group B), central nervous system (group N) and cardiovascular system (group C).

No conflict of interest.