RESEARCH ARTICLE Adverse-drug-reaction related admissions to a hospital in Scotland Yvonne Hopf Æ Margaret Watson Æ David Williams Received: 3 February 2008 / Accepted: 4 July 2008 / Published online: 25 July 2008 Ó Springer Science+Business Media B.V. 2008 Abstract Aims To apply established methods to identify ADR-related admissions and to determine the proportion which was preventable and which were caused by non- prescription medicines (NPMs). Methods This prospective, observational study screened all acute hospital admissions (n = 1,101) by ward pharmacists over a 2-week period. Suspected ADR-related admissions were reported to the researcher and established criteria were used to evaluate probability, causality and preventability of the ADR-rela- ted admissions. Results Of the 1,101 emergency admissions which occurred during the study period, 30 were categor- ised as ADR-related, equating to a prevalence of 2.7% (95% CI, 1.8–3.7%). Three (9.7%) of the 30 admissions were associated with NPMs. The ADR was the dominant reason for admission in 56.7% (n = 17/30) and only 13.3% (n = 4/30) of all reported admissions were assessed as unavoidable. Conclusion The proportion of ADR-related admissions was lower than in previous studies in the UK. A substantial proportion of ADRs was associated with NPMs, highlighting the need for greater awareness amongst patients, prescribers and other health care professionals regarding possible serious adverse effects caused by these medicines. Keywords Adverse drug reaction Á Hospital admission Á Non-prescription drug Á OTC medicines Á Prescription medicines Á Scotland Impact of findings on practice • Most ADR related hospital admissions are caused by medicines that have been on the market for some time. • Potential ADRs in the primary care setting need to be monitored better. • Hospital admissions can also be caused by ADRs of products that are available without prescription. Introduction An adverse drug reaction (ADR) is defined as a noxious and unintended response to a drug which occurs at doses normally used in man [1]. In a recent review of interna- tional studies, ADRs were shown to account for 2–6% of all hospital admissions [2] and contribute substantially to health care costs as a result of prolonged hospital stay or additional intervention. A meta-analysis of 25 international studies, found that 4.2–6% [median 5.8%] of all admissions to medical departments were caused by ADRs [3]. A large prospective observational study of 18,820 patients showed a prevalence of 6.5% (95% CI, 6.2–6.9%) ADR-related hospital admissions in two hospitals in Merseyside, England [4]. In 80% of these cases, the admissions were directly related to the ADR. Most reactions were definitely or possibly avoidable with 28% being rated as unavoidable. It is estimated that up to 250,000 admissions per annum are related to ADRs in the UK with associated costs of £466 million for the NHS [5]. Most studies aim to identify ADRs Y. Hopf Department of Pharmacy, Aberdeen Royal Infirmary, Foresterhill, Aberdeen AB25 2ZN, Scotland, UK M. Watson Department of General Practice and Primary Care, University of Aberdeen, Aberdeen, Scotland, UK D. Williams (&) Department of Clinical Pharmacology, Aberdeen Royal Infirmary, Foresterhill, Aberdeen AB25 2ZN, Scotland, UK e-mail: davidwilliams4@nhs.net 123 Pharm World Sci (2008) 30:854–862 DOI 10.1007/s11096-008-9240-5