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Prince of Wales Hospital Releases Investigation Report on Warfarin Incident

Prince of Wales Hospital today (November 12) released the investigation report on wrong dosage of anticoagulant Warfarin being given to an 84-year-old female patient.

The investigation panel was set up on September 13 to investigate the facts of the incident and causes of wrong dosage being given. It has also made recommendations on improvement measures.

According to the report, the patient had chronic rheumatoid heart disease, hypertension, diabetes and history of stroke. She attended the medical outpatient clinic on August 10, 2010. The attending doctor reviewed the patient’s blood coagulation index and adjusted the dosage of Warfarin that she had been taking, from 2.5 mg on odd days and 2 mg on even days, to 2mg daily. The doctor deleted the old entry of 2.5 mg on odd days in the electronic prescription system, and checked that the remaining entry was “2 mg” in the dosage field and “daily” in the frequency field. However, the doctor did not realize that the supplementary frequency field was still showing “on even days” and not updated. Also, the doctor did not notice that the dosage on the prescription print-out was 2 mg on even days, which was only half of the intended dosage.

The patient was admitted to Prince of Wales Hospital due to symptoms of stroke. Her condition deteriorated subsequently and was complicated by urinary tract infection and septicaemia. She passed away on September 5.

The panel identified the following causes which contributed to the incident:
- The electronic prescription system is not user-friendly. The advanced options are especially difficult to use.
- There is lack of training on the proper use of the system.
- It is not easy for pharmacy staff to notice any abnormal prescriptions of Warfarin.
- The designated Warfarin clinic is saturated. Patients are managed in different clinics where doctors may not be familiar with the proper prescription of Warfin.
- The doctor failed to communicate clearly with the patient and relative about the correct drug dosage.

The panel made the following recommendations:
- Improve the design of the electronic prescription system to make it more user-friendly and avoid using misleading wordings.
- Strengthen training on the proper use of the system. New prescriptions should be made instead of modifying old prescriptions in the advanced options.
- Establish a mechanism to alert pharmacy staff to check Warfarin dosage.
- Strengthen the capacity of the Warfarin clinic to meet service needs.
- Enhance communication with patients and carers and engage them in disease management. Give out Warfin booklet to document the drug regime.

The hospital met the deceased’s family to explain the details of the report and follow up measures, and again expressed our sympathy to them. The hospital accepts full responsibility of the incident and will follow up with the relatives on the compensation. The case was reported to the Coroner. The doctor involved will be followed up by the hospital according to the established human resources procedures.

Dr. SO Hing-yu, Cluster Coordinator (Quality & Safety), New Territories East Cluster / Director (Intensive Care Unit), Prince of Wales Hospital served as chairman of the investigation panel. Members included:
- Dr. WONG Kwan-keung, Cluster Coordinator (Drugs & Therapeutics), New Territories East Cluster / Chief of Service (Medicine), North District Hospital / Director (Critical Care Medical Unit), Alice Ho Miu Ling Nethersole Hospital
- Dr. LEUNG Chi Bon, Cluster Coordinator (Clinical Informatics), New Territories East Cluster / Deputy Chief of Service (Medicine), Prince of Wales Hospital
- Dr. CHAN Hiu-ming, Chairman (Medication Safety Committee), Kowloon Central Cluster / Specialist in Neurology, Consultant Physician (Medicine), Queen Elizabeth Hospital
- Mr. KWONG Yiu-sum, Senior Pharmacist, Pharmacy Professional & Clinical Services, Hospital Authority Head Office