Authors of the University of Bristol-led study, published in the British Journal of General Practice, say that while these findings may be unsurprising to clinicians, they may be concerning or confusing to patients, especially when accessing results online.
The audit, which collected anonymised data on blood tests for over 2,500 patients from 57 GP practices in England, Scotland, Wales and Northern Ireland, also found that a quarter of tests may have been partially or fully unnecessary when reviewed retrospectively by another clinician.
Around half of tests (48%) did not lead to any change in management or reassurance, 13.4% led to further blood tests or repeat blood tests, and 2.7% led to further radiology tests.
The most common reasons for testing were symptoms (43.2%), monitoring of existing disease (30.1%), and monitoring of existing medications (10%).
Only around half of tests were requested by GPs, reflecting the multidisciplinary nature of primary care. On average 4.5 tests were requested simultaneously per patient.
The study, Why Test?, is the first from a new national collaborative of academics and primary care clinicians (PACT) and was supported by the National Institute for Health and Care Research Applied Research Collaboration West (NIHR ARC West) and NHS Bristol, North Somerset and South Gloucestershire Integrated Care Board Research Capability Funding.
Dr Jessica Watson, a GP and NIHR Clinical Lecturer in General Practice in Bristol's Centre for Academic Primary Care, said: "Rates of blood testing in primary care have increased over the last twenty years. In this study, we wanted to explore who requests blood tests and why, and what the outcomes are.
"The results have important implications for how primary care clinicians talk to patients about blood tests, to ensure that they have a better of understanding of why a test may or may not be necessary and realistic expectations of the role of blood tests in their care. Many tests don’t lead to a diagnosis or change in treatment, although they may still be important to rule something out or provide reassurance.
"There is also a need for better evidence to inform judgements on whether a test is necessary or not, as sometimes this judgement is only possible with hindsight when test outcomes are known. Unnecessary tests could lead to increased anxiety for patients, increased workload for GPs and increased costs for the NHS. We need better evidence to help us ensure that patients get the right test at the right time.
"We are grateful to PACT members for collaborating on this research. Without their help, this data collection would not have been possible."
The findings were presented this week at the Society for Academic Primary Care Annual Scientific Meeting in Brighton.
Paper
'Why test? Study: a UK-wide audit using the Primary Care Academic CollaboraTive to explore the reasons for primary care testing' by in British Journal of General Practice