Research into inflammatory marker testing has led to a reduction and rationalisation in their use by GPs in both Bristol, North Somerset and South Gloucestershire (BNSSG) and the South West Peninsula.

In BNSSG alone, data suggests the research saved the local NHS nearly £115,000 and GPs more than 600 hours a year. Further savings will have come from avoiding follow-on appointments for thousands of false positives.

The research was led by Dr Jessica Watson, an academic GP at the Centre for Academic Primary Care (CAPC) at the University of Bristol, as part of her ARC West supported PhD.

Jess explored the use of inflammatory marker blood tests in primary care. They detect inflammation in the body, caused by many diseases including infections, auto-immune conditions and cancers. The tests don’t identify what’s causing the inflammation: it might be as simple as a viral infection, or as serious as cancer.

Nationally the use of inflammatory markers has been increasing, with significant geographic variation in testing rates. Jess’s previous research has shown that GPs aren’t certain about how to use inflammatory markers appropriately. This is important as unnecessary tests can cause anxiety for patients, while increasing costs for the NHS and workload for clinicians.

The research

As part of the PhD, Jess analysed the primary care data of 200,000 people from the Clinical Practice Research Datalink. She looked at the use of three inflammatory marker tests, CRP, ESR and PV, and showed that:

• Inflammatory markers aren’t a useful non-specific ‘rule-out’ test for underlying disease, because they aren’t sensitive enough
• Testing both CRP and PV together doesn’t improve diagnostic accuracy
• CRP has superior accuracy for infections and is equivalent for autoimmune conditions and cancers. It is also cheaper.

She also explored how these tests were communicated to patients. She found a mismatch between patients’ and doctors’ expectations and understanding of these blood tests. Patients described being unaware which tests had been done, or why. Patients were frustrated and anxious when test results did not fulfil their expectations.

Normal results were perceived by doctors to offer reassurance. However, patients could feel these results invalidated their symptoms and left them uncertain about the cause of their problems. The study concluded that better communication from doctors about the purpose of testing, and their expectations, could reduce patients’ frustration and lay the foundations for better shared decision-making. This work was selected for an NIHR Alert.

Changing practice

The findings of the data study informed a clinical effectiveness project in the Bristol, North Somerset and South Gloucestershire (BNSSG) area. Jess worked with a project team of five local GPs and the Integrated Care Board (ICB) Clinical Effectiveness team. Following feedback from GPs, the team developed a guideline for inflammatory marker testing, with input from hospital specialists, which was published in December 2019.

To help bring the guideline’s recommendations into practice, the online system used by clinicians to order blood tests was changed in January 2020. This included new popups to require a valid indication for testing to be chosen for ESR and PV, and discourage the use of CRP as a non-specific rule-out test. ESR and PV were also moved to a less prominent position on the ordering screen, and tests were removed from profiles where inflammatory marker testing was not clinically indicated.

In the South West Peninsula region, the Peninsula Pathology Effectiveness Group developed a similar guideline to reduce the use of PV testing, implemented in December 2021. Changes were made to the blood test ordering system to remove PV from the front screen in June 2022.

Saving NHS resources

In 2020, the first year after the new guidelines in BNSSG were brought in, there were 36,256 fewer inflammatory marker tests, with a direct cost saving of £114,611. If we assume a GP spends 1 minute reviewing each test, this reduction in testing saved around 604 hours of GP time in the first year.

In addition, Jess’ research indicates that 36,245 fewer tests would avoid approximately 8,556 false positive results. In turn this would save 25,741 GP appointments, 8,302 blood test appointments and 870 referrals, that would otherwise have resulted from these positive results.

Data on testing rates in 2020 is likely to have been impacted by the Covid-19 pandemic, however more recent data from one laboratory in the BNSSG area has confirmed the reductions in PV testing have been sustained since 2020, with 4,441 tests conducted in 2022 compared to 59,235 in 2018.

Data collected by an Exeter laboratory since the guidelines were implemented in Devon and Cornwall showed PV testing reduced by 75%, which is about 3,000 fewer tests per month.

Improving communication with patients

Jess was asked to review and update patient information leaflets about the inflammatory markers CRP, ESR and PV for the Lab Tests Online website. This website is produced by the Association for Clinical Biochemistry and Laboratory Medicine, and is a source of trusted information on blood test for clinicians and patients.

She has also been invited to speak to the NHS App Team at NHS England. They have used the findings about communication to patients to improve the way test results are presented to patients on the NHS App.

Jess is building on this aspect of the work with Test Talk Tools. This project looks at the evidence on how blood test communication in primary care can be improved.

Jess says: “Our research into inflammatory marker testing is important to help ensure that patients get the right test at the right time. By collaborating with the clinical effectiveness team in BNSSG we were able to maximise the impact of these findings.

“Despite the additional challenges of the COVID-19 pandemic, the data from 2022 shows a sustained reduction in the use of PV tests, which were shown to be more costly and less accurate than CRP tests for most patients. This has important implications for primary care workload, NHS costs and sustainability.”

Jess has also just published findings from the Why Test? project funded by BNSSG ICB, which builds on her PhD. Why Test? aims to find out who orders blood tests and why, and how GPs use the results. Read Jess’s latest blog, with Dr Ola Abdellatif from the Primary Care Academic Collaborative (PACT), on the power of collaboration in the Why Test? project.