A mixed methods analysis of clozapine errors reported to the National Reporting and Learning System

Keval Dabba, Matthew Elswood, Ahmed Ameer, Ian Maidment

Research output: Contribution to journalArticlepeer-review


Purpose: To review and analyse medication errors related to clozapine, an atypical antipsychotic, that were reported to the National Reporting and Learning System (NRLS). Methods: Following extraction of one year of clozapine related errors from the NRLS, a qualitative analysis (thematic analysis and re-classification) and quantitative analysis was performed. An incident was considered a clozapine error if there was a failure in its medication process (i.e. an error in the prescribing, dispensing, preparing, administering, monitoring or advising of clozapine). Results: “Issues with stock/supply/ordering” was the most common theme derived from the qualitative thematic analysis (n = 338), followed by wrong dose/strength/frequency (n = 221) and medication omissions (n = 202). Most errors occurred in the “administration/supply” medication stage. Over half of reported clozapine incidents involved people 26 to 55 years old (n = 830) and 82% of errors were reported by mental health services (n = 1270). Only 1.5% of reports were classed as moderate/severe harm. Conclusion: Issues with availability, stock, and supply were found to be the most common causes. This usually entailed a lack of stock to fulfil a patient's dose/supply. Such incidents could potentially be reduced by improved management of the supply process, and liaison between pharmacy and clinical staff. The implementation of emergency drug cupboards at the discretion of an on-call pharmacist may prove to be a preventative measure for such errors. Despite the potential adverse effects associated with clozapine, very few incidents led to moderate/severe harm. Encouragement of NRLS reporting is recommended for incidents of all degrees of harm.

Original languageEnglish
Pages (from-to)657-664
Number of pages8
JournalPharmacoepidemiology and Drug Safety
Issue number5
Early online date10 Feb 2019
Publication statusPublished - 1 May 2019

Bibliographical note

This is the peer reviewed version of the following article: Dabba K, Elswood M, Ameer A, Gerrett D, Maidment I. A mixed methods analysis of clozapine errors reported to the National Reporting and Learning System. Pharmacoepidemiol Drug Saf. 2019;1–8, which has been published in final form at https://doi.org/10.1002/pds.4727.  This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.


  • clozapine
  • drug safety
  • medication errors
  • mental health
  • near misses
  • patient safety
  • pharmacoepidemiology
  • pharmacovigilance
  • qualitative analysis
  • quality improvement
  • thematic analysis


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