Drug Safety 2005; 28 (9): 817-824 ORIGINAL RESEARCH ARTICLE 0114-5916/05/0009-0817/$34.95/0  2005 Adis Data Information BV. All rights reserved. Computer Calculated Dose in Paediatric Prescribing Richard C. Kirk, 1 Denise Li-Meng Goh, 1,2 Jeya Packia, 3 Huey Min Kam 4 and Benjamin K.C. Ong 2,5 1 Department of Paediatrics, The Children’s Medical Institute, National University Hospital, Singapore 2 Faculty of Medicine, National University of Singapore, Singapore 3 Information Technology Division, National Health Care Group, Singapore 4 Department of Pharmacy, National University Hospital, Singapore 5 Department of Medicine, National University Hospital, Singapore Background and objective: Medication errors are an important cause of hos- Abstract pital-based morbidity and mortality. However, only a few medication error studies have been conducted in children. These have mainly quantified errors in the inpatient setting; there is very little data available on paediatric outpatient and emergency department medication errors and none on discharge medication. This deficiency is of concern because medication errors are more common in children and it has been suggested that the risk of an adverse drug event as a consequence of a medication error is higher in children than in adults. Objective: The aims of this study were to assess the rate of medication errors in predominantly ambulatory paediatric patients and the effect of computer calculat- ed doses on medication error rates of two commonly prescribed drugs. Methods: This was a prospective cohort study performed in a paediatric unit in a university teaching hospital between March 2003 and August 2003. The hospital’s existing computer clinical decision support system was modified so that doctors could choose the traditional prescription method or the enhanced method of computer calculated dose when prescribing paracetamol (acetaminophen) or promethazine. All prescriptions issued to children (<16 years of age) at the outpatient clinic, emergency department and at discharge from the inpatient service were analysed. A medication error was defined as to have occurred if there was an underdose (below the agreed value), an overdose (above the agreed value), no frequency of administration specified, no dose given or excessive total daily dose. The medication error rates and the factors influencing medication error rates were determined using SPSS version 12. Results: From March to August 2003, 4281 prescriptions were issued. Seven prescriptions (0.16%) were excluded, hence 4274 prescriptions were analysed. Most prescriptions were issued by paediatricians (including neonatologists and paediatric surgeons) and/or junior doctors. The error rate in the children’s emer- gency department was 15.7%, for outpatients was 21.5% and for discharge medication was 23.6%. Most errors were the result of an underdose (64%; 536/ 833). The computer calculated dose error rate was 12.6% compared with the