Shared learning database

Nottingham Universities Hospitals NHS Trust
Published date:
January 2021

Patients on warfarin need to be within a therapeutic range in order to remain safe. We looked at the time pre-COVID-19, pre lockdown, lockdown and post lockdown, and noted that patients time in therapeutic range during lockdown dropped. This means that patients were less safe during lockdown and at higher risk of developing clots or bleeding issues.

This service improvement study noted that this may have been due to changes relating to alcohol intake, diet, lifestyle and stress / bereavement. As a service, we looked to ensure that we are in a position to combat this in the event of another lockdown. When this did, we were better prepared to manage patients however this is an ongoing learning experience. We have attempted to offer ‘drive through’ blood taking sessions, plan smaller clinics, and switched more patients to Direct Oral Anticoagulants (DOACs) when suitable, (NICE KTT16) amongst other solutions.

We will also be sending a letter to all patients and GPs reminding them of the things that can affect the international normalised ratio (INR) results and therefore their time in therapeutic range. This service improvement approach is best suited to work when following NICE Clinical guideline CG180.

Guidance the shared learning relates to:
Does the example relate to a general implementation of all NICE guidance?
Does the example relate to a specific implementation of a specific piece of NICE guidance?


Aims and objectives

The aim of this service improvement project is to ensure that patients are kept as safe as possible during difficult times. Patients taking warfarin should remain within a set therapeutic range. Failure to do so puts them at higher risk of developing clots or bleeding issues. It was noted during lockdown that the amount of time patients spent in therapeutic range dropped. This was found following discussion with patients who noted changes in lifestyle, diet and alcohol intake amongst other issues.

NICE guidelines (CG180) clearly state the importance of monitoring patients’ time in therapeutic range and through using these recommendations we wanted to ensure that our patients were kept as safe as possible.

We aimed to understand the barriers that affected patients’ INR results and how we could combat these if we were to fall into another COVID-19 related lockdown. We believe that this information can be useful to all units nationally and internationally in helping maintain high standards regarding patient time in therapeutic range and patient safety.   

Reasons for implementing your project

Patients are counselled when commenced on warfarin but they may be on the medication for many years without being given any further education. If patients are tested at their GP surgery they may not have any contact with the anticoagulation team regarding such issues. We noted that pre-COVID-19, pre lockdown and post lockdown, patient time in therapeutic range remained generally consistent.

However, during lockdown the percentage of patients in safe therapeutic range dropped significantly. We measured the same period during the previous year to further explore this point. We noted that if patients were reminded of the impact of certain lifestyle choices upon their INRs we may be able to prevent such fluctuation. We also aimed to review patients who were suitable for the newer DOAC medication that involved no blood tests. We aimed to leave patients longer between tests during this lockdown period if possible to reduce the number of trips to hospital. The combination of these issues will no doubt save the trust money and the patients a lot of time. We wanted to make the experience of coming to hospital safer for those patients who needed to come to hospital so offered drive through services in correspondence with patients to help ease their stress during this time. We used information from around 3,200 INR tests during each period.

How did you implement the project

NICE guideline CG180 recommends that factors that may contribute to poor anticoagulation therapy should be regularly assessed. These include illness and lifestyle factors such as diet and alcohol consumption.

Following discussions with patients we noted many were mentioning such changes so decided to determine if these had an effect on patient Time in Range (TIR). We used the DAWN AC software to determine all patients who tested in each period TIR. When identifying a drop in patient TIR during lockdown we noted patients were therefore less safe. We reviewed patients that could be swapped to DOACs to reduce the number of interacting issues and made other plans as noted above to make testing easier for patients. This incurred no extra costs to our service only time of staff already on shift.

A nurse specialist performed the service improvement study before taking it to management who helped implement the required changes. Patients and GPs will be contacted with education information reminding them of the drug interactions with warfarin. The funds for this were applied for through charity services at the hospital.

Key findings

It can be seen that in the period prior to any COVID-19 cases being reported in the UK, 82.5% of patients who tested were within their therapeutic time for the majority of time. This remained fairly consistent in the period leading up until lockdown where 81.5% of patients were within range for 55-100% of the time period.

However, from the period of lockdown it can be seen that this number dropped to 77.5 percent. This is a 5% drop in figures since the pre lockdown period. In contrast in the period post lockdown the number of patients within their therapeutic range for the majority of time rose once more to 80.9%. It can be seen therefore that the period of lockdown for the UK did see a detrimental effect on patient’s time in therapeutic range.

In order to provide a more thorough look at the importance of this period, it was decided to monitor the figures from the same dates the year before (2018-2019). The pre-COVID-19 dates (9th September – 14th December 2019) showed 82.5% of patients within therapeutic range for the majority of time in 2019. In 2018 these figures were 80.4%. In the period from December 16th – March 23rd the 2019-20 numbers were 81.5% and the 2018-19 period were consistent at 80.1%.

On March 23rd 2020, the UK went into lockdown and the number dropped to 77.5% whereas the year before this number was 82.4% Showing a decrease in lockdown of 4.9%. Post-lockdown this number was 80.9% and the previous year’s results were 83%.

Complete results are set out in the table below:



% of Time in Therapeutic Range

Number of patients (percentage)


Pre covid

9.9.19 – 14.12.19

Pre lockdown

16.12.19 – 23.3.20


23.03.20 – 04.07.20

Post lockdown

06.07.20 – 12.10.20



146 (4.6%)

169 (5.2%)

191 (5.9%)

196 (5.9%)


154 (4.8%)

172 (5.3%)

212 (6.5%)

172 (5.2%)







258 (8.1%)

256 (7.9%)

326 (10.1%)

263 (8%)


346 (10.9%)

365 (11.3%)

391 (12.1%)

384 (11.6%)


2276 (71.6)

2263 (70.2%)

2120 (65.4%)

2288 (69.3%)






What was also interesting to note was the number of patients who were significantly out of their therapeutic range during this time, this is noted in the table below.




Percentage of patients significantly out of therapeutic range


Pre covid

9.9.19 – 14.12.19

Pre lockdown

16.12.19 – 23.3.20


23.03.20 – 04.07.20

Post lockdown

06.07.20 – 12.10.20







>5 <8















It is clear to see from these figures that patient’s time in therapeutic range was impacted during the period of lockdown. It was also noted that patients were more likely to get high INRs than low INR results at this time. This shows that patients were more likely to be at risk of developing complications due to bleeding than increasing their risk of developing a clot. 

Knowing this information, we can plan for further lockdown events and manage patients appropriately, hopefully preventing serious events, patient admissions and as many blood tests as many patients were swapped to DOACs

Key learning points

Through this study it was learnt that patients would benefit with more persistent education; if patients are aware of interactions they can be helped to be more involved in their care which is the gold standard of any care service.

We want patients to feel they are involved in their treatment and by involving them in the process with education we are able to implement this.

It is important to regularly monitor patients’ TIR and to make this a part of the anticoagulation nurse specialist role.

NICE guidelines recommend patients’ TIR is reviewed six-monthly to ensure patients are kept as safe as possible. This can be challenging with staff issues so it would be wise to implement this process as soon as possible so that areas can be in the best possible position ahead of any further lockdown events.

We found extending our clinic times reduced patients in the waiting room at one time and allowed more flexibility to patients to fit in testing around their work schedules. We found that this greatly helped patients to continue to test during difficult times.

Contact details

Matthew Roberts
Clinical Nurse Specialist
Nottingham Universities Hospitals NHS Trust

Secondary care
Is the example industry-sponsored in any way?