Medication errors
: capture and prevention by pharmacy

  • Mark Tomlin

Student thesis: Doctoral Thesis


Introduction This thesis looks at the pharmacist’s contribution to the capture of medication errors and preventing harm reaching patients. It has several components: an analysis of annual surveys of interventions made by pharmacists at a large teaching hospital, a re-coding of these surveys to see how many interventions were the result of prescribing errors, and an experiment in A&E where the pharmacist drafted the first prescription chart. Methods One-week surveys of pharmacist interventions were regularly made at Southampton General Hospital between 1999 and 2009. These were analysed for trends, then recoded to identify the proportion that were caused by prescribing errors. In addition, a controlled trial was conducted to investigate the effects on prescribing error rate, of a pharmacist obtaining an accurate medication history in A&E, then transcribing the data onto the first inpatient prescription. Key findings In the period 1999-2001, the average number of interventions in each week long survey was 575 and during 2005-9 it was 973. This was a statistically significant increase. More interventions were recorded as serious in the latter period. The rate of interventions also increased from between one per every five and seven patients (31 to 45 prescribed items) to one per every one to two patients (8 to 20 items). The severity of interventions also increased, with between one and five deaths avoided each week. Almost three quarters of pharmacists’ interventions (73.9%) were triggered by prescribing errors, giving an error rate of 644 prescribing errors per week, or 6.2 per 100 prescribed items. These data are in contrast to the Trust submitting 918 error reports per year to the NPSA, the majority of which were administration errors reported by nurses. Nearly a half (45.3%) of all prescribing errors occurred during the admission phase of the hospital episode. Two thirds (67.1%) of prescribing errors detected were errors of omission - things that had not been done. Prescribing errors of commission occurred mainly during the inpatient phase and errors of omission during the admission phase. A quarter of prescribing errors were planning errors. These were failures to follow guidelines, failures to review patients’ prescriptions, manage interactions, and adjust dosage in liver or renal failure or in response to TDM results. One fifth (21.7%) of the patients had events or symptoms that contributed to the admission that could be explained by the medicines they were consuming. Over half of these were potentially avoidable by better monitoring or product selection. A pharmacist working in A&E to obtain complete and accurate drug histories, then transcribing the data onto the first prescription, produced a trend to reduction in the generation of errors throughout the whole hospital episode. Conclusions Analysing pharmacist’s interventions is a useful method of investigation prescribing errors and ways to stop them happening. First prescriptions written by pharmacists should provide an effective means of reducing errors which may be promulgated throughout the hospital stay.
Date of AwardJun 2011
Original languageEnglish
Awarding Institution
  • University of Portsmouth
SupervisorDavid Brown (Supervisor)

Cite this