Safe and effective use of Warfarin
In this Audit
Warfarin is the medicine most frequently associated with adverse drug reactions in New Zealand. Improving the safety
of warfarin treatment involves educating patients, ensuring that patient notes are complete and easy to access, and adhering
to safe prescribing practices.
Patient education involves sharing information about bleeding risk, diet, medicines and testing. All patients should
be fully informed prior to beginning anticoagulation treatment and then have their management discussed regularly during
Accurate and complete recording of patient information means that any prescriber is able to easily access key information
about the patient’s management. This includes not only that the patient is prescribed warfarin, but the condition for
which it is prescribed, the brand of warfarin, the planned duration of treatment, the target INR range, their INR levels,
when INR testing last occurred and when it should next occur. The latest INR result and current warfarin dose should also
be clearly stated in the patient’s notes. This information should be immediately obvious to anyone accessing the notes,
i.e. a locum or practice nurse. This can be done in several ways in most practice management software, e.g. using a “screening”
entry in Medtech which makes the information easier to find rather than identifying it from a number of consultation notes.
Safe prescribing means that all necessary information is available to the pharmacist on the prescription and also to
the patient (on the medicine label). A prescription for warfarin should include:
- The brand name of the prescribed warfarin (this is in contrast to the usual recommendation to only prescribe medicines
by generic name; warfarin has a narrow therapeutic range and there may be differences in bioavailability
between brands of warfarin)
- Labelling that highlights the importance of ongoing INR monitoring, e.g. “Take the dose instructed by your doctor
or nurse. You need regular INR tests to make sure this dose is safe for you”, instead of labels such as “PRN” or “as
Regular INR testing is used to ensure that anticoagulation is effective and allows warfarin doses to be changed as required.
For most people, e.g. patients with atrial fibrillation, the recommended target INR range is 2.0 – 3.0. Some people with
prosthetic valves or haemodynamically significant valvular disease require a higher INR, e.g. within the range 2.5 – 3.5.
To minimise confusion and ensure safe and effective anticoagulation, it is recommended that a systematic, practice-wide
approach to warfarin treatment and the maintenance of INR levels within target range is adopted. Common protocols should
- How to initiate warfarin for patients in primary care, i.e. indications and recommended INR range, starting doses,
frequency of monitoring, who will follow patients and their warfarin treatment
- Patient education including the provision of appropriate written material
- A standard method of recording that a patient is on warfarin plus other key information, i.e. the current warfarin
dose, most recent INR result and when the next INR test is due
- How to monitor warfarin treatment, significant medicine interactions, modifying warfarin dosage and frequency of INR
- If the practice has a supply of vitamin K (phytomenadione) and where it is kept
All patients in the practice who are currently being treated with warfarin can be audited to assess whether they have
been prescribed warfarin safely. The following information should be readily available in their patient record or in the
- All necessary information regarding a patient’s warfarin treatment
- Information regarding a patient’s last INR and when the next INR test should be requested
Criteria for a positive result
For a patient to be considered a positive result for the audit, their notes should contain all of the following information:
- That the patient is taking warfarin
- The condition for which they are taking warfarin
- Their target INR range
- When the warfarin was initiated
- When the warfarin will be stopped, i.e. the duration of treatment
- The brand of warfarin
- The current warfarin dose
- The date of their most recent INR test
- The result from their most recent INR test
- When their next INR test should be requested
Recommended audit standards
Given the level of risk associated with warfarin and the high number of adverse medicine events reported each year in
New Zealand, the standard for this audit should ideally be high. A recommended standard would be for 90% of patients to
have all the required information recorded in the patient notes. In addition, there should ideally be an improvement in
the achieved percentage between the first and second audit cycles.
All patients within the practice currently prescribed warfarin are eligible for this audit.
You will need to have a system in place that allows you to identify these eligible patients. Many practices will be
able to identify patients by running a ‘query’ through their PMS system. Identify all patients who have had a prescription
The number of eligible patients will vary according to your practice demographic. If you identify a large number of
patients, take a random sample of 30 patients whose notes you will audit (the first 30 results returned is sufficiently
random for the purposes of this audit).
Use the data sheet provided to record your data.
A positive result is any patient who has a tick in each of the “Patient
notes” columns. The percentage achievement can be calculated by dividing the number of patients with a positive result
by the total number of patients audited.
Identifying opportunities for CQI
The first step to improving medical practice is to identify where gaps exist between expected and actual performance
and then to decide how to change practice.
Decide on a set of priorities for change and develop an action plan to implement any changes.
It may be useful to consider the following points when developing a plan for action.
Problem solving process
- What is the problem or underlying problem(s)?
- Change it to an aim
- What are the solutions or options?
- What are the barriers?
- How can you overcome them?
Overcoming barriers to promote change
- What is achievable – find out what the external pressures on the practice are and discuss ways of dealing with them
in the practice setting
- Identify the barriers
- Develop a priority list
- Choose one or two achievable goals
- No single strategy or intervention is more effective than another, and sometimes a variety of methods are needed to
bring about lasting change
- Interventions should be directed at existing barriers or problems, knowledge, skills and attitudes, as well as performance
Monitoring change and progress
It is important to review the action plan at regular intervals. It may be helpful to review the following questions:
- Is the process working?
- Are the goals for improvement being achieved?
- Are the goals still appropriate?
- Do you need to develop new tools to achieve the goals you have set?
- Following the completion of the first cycle, it is recommended that practitioners complete the first part of the
activity summary sheet (Appendix 1).
Undertaking a second cycle
In addition to regular reviews of progress, a second audit cycle should be completed in order to quantify progress on
closing the gaps in performance.
It is recommended that the second cycle be completed within 12 months of completing the first cycle. The second cycle
should begin at the data collection stage. Following the completion of the second cycle it is recommended that practitioners
complete the remainder of the CQI activity summary
Claiming MOPS credits
This audit has been endorsed by the RNZCGP as an Audit of Medical Practice activity (previously known as Continuous
Quality Improvement - CQI) for allocation of MOPS credits; 10 credits for
a first cycle and 10 credits for a second cycle. General practitioners taking part in this audit can
claim credits in accordance with the current MOPS programme.
To claim points go to the RNZCGP website: www.rnzcgp.org.nz
Record your completion of the audit on the MOPS Online credit summary, under the
Audit of Medical Practice section.
From the drop down menu, select the audit from the list or select “Approved practice/PHO audit” and record the audit name in “Notes”, the audit date and 10 credits.
General practitioners are encouraged to discuss the outcomes of the audit with their peer group or practice.
As the RNZCGP frequently audit claims you should retain the following documentation, in order to provide adequate evidence of participation in this audit:
- A summary of the data collected
- An Audit of Medical Practice (CQI) Activity summary sheet (included as Appendix 1).