Research suggests that 237 million medication errors occur at some point in the medication process in England per year.

When errors occur in prescribing high-risk medications for older patients with multiple medical problems, there is a significant risk of serious harm. High-risk medicines are those which risk significant patient harm or death when used in error, such as warfarin.

Reference event

The reference event in this investigation is an incident where a hospital inpatient was administered repeated doses of warfarin in error and suffered significant harm as a result. The error was detected after six days by a ward-based clinical pharmacist.

Investigation summary

This patient safety investigation looks at the:

  • Systems and processes which underpin the identification, prescribing and administration of warfarin for older inpatients.
  • Main patient safety risks arising from the prescribing and administration of warfarin and other high-risk drugs.
  • Main patient safety defences that act to protect people from medication errors with high-risk medicines.

Download and read the full report.

Safety recommendations

We’ve made three safety recommendations as a result of this investigation. Safety recommendations have been made to NHS England and NHS Improvement, the Royal Pharmaceutical Society, and the NHS Specialist Pharmacy Service.

We expect a response to our safety recommendations within 90 days of publication of the investigation report. The responses will be shared here when they’re available.

NHS England and NHS Improvement

It is recommended that NHS England and NHS Improvement carry out work to understand and further define the work of hospital clinical pharmacy teams, including the period between initial medicine reconciliation and discharge, in consultation with relevant stakeholders.

Royal Pharmaceutical Society

It is recommended that the Royal Pharmaceutical Society, supported by NHS England and NHS Improvement, should provide guidance on models of hospital clinical pharmacy provision. The guidance should provide information on the models’ ability to enhance safety and healthcare resilience and include consideration of the appropriate skill mix and experience within the clinical pharmacy team.

NHS Specialist Pharmacy Service

It is recommended that the NHS Specialist Pharmacy Service should update its resource on the prioritisation of hospital clinical pharmacy services to facilitate the dissemination of developments in good practice and policy with respect to pharmacy prioritisation and the issues highlighted in this report.


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