Objective To describe the cost–benefits of pharmacy-led medicines reconciliation (MR) on admission by applying a theoretical model (University of Sheffield School of Health and Related Research—SCHARR model) to real-world data.

Methods This was a retrospective, single-centre study. Setting 1000-bedded teaching hospital in London, UK. Clinical pharmacy contributions related to unintended medication discrepancies (averted preventable adverse drug events, pADEs), documented by pharmacy staff on prearranged days during 2012, were assessed for clinical significance by a panel of senior clinical pharmacists using the SCHARR model. Costs avoided were allocated according to the SCHARR model. Pharmacy staff carrying out admission MR were timed. Net cost avoidance was calculated by subtracting cost of time taken to carry out MR from the costs avoided by averting pADEs. Sensitivity analyses were carried out.

Results 118 pADEs averted as a result of MR were recorded over the 6 reporting days. 116 were rated for clinical significance. Gross costs avoided were £36 135–£75 249 (€44 446–€92 556). The admission MR process was timed for 48 patients. The mean time to complete MR for one patient was 14 min (range 1–40 min). The cost of carrying out one MR, based on the cost of employing a first-level post-foundation clinical pharmacist was £7.56 (€9.30). The net benefit of one MR was £34–£80 (€42–€98). The benefit:cost ratio was 5.53:1–11.51:1.

Conclusions Pharmacy-led MR on admission has significant economic, as well as clinical benefits. Further work is required for full economic evaluations of MR.