Temporal growth and geographic variation in the use of laboratory tests by NHS general practices: using routine data to identify research priorities

Abstract

BackgroundLaboratory tests are extensively used for diagnosis and monitoring in UK primary care. Test usage by GPs, and associated costs, have grown substantially in recent years. AimThis study aimed to quantify temporal growth and geographic variation in utilisation of laboratory tests. Design and settingRetrospective cohort study using data from general practices in the UK. MethodData from the General Practice Research Database, including patient demographics, clinical details, and laboratory test results, were used to estimate rates of change in utilisation between 2005 and 2009, and identify tests with greatest inter-regional variation, by fitting random-effects Poisson regression models. The study also investigated indications for test requests, using diagnoses and symptoms recorded in the 2 weeks before each test. ResultsAround 660 000 tests were recorded in 230 000 person-years of follow-up. Test use increased by 24.2%, from 23 872 to 29 644 tests per 10 000 person-years, between 2005 and 2009. Tests with the largest increases were faecal occult blood (121%) and C-reactive protein (86%). There was substantial geographic variation in test utilisation; GPs in some regions requested tests such as plasma viscosity and cardiac enzymes at a rate more than three times the national average. ConclusionIncreases in the use of laboratory tests have substantial resource implications. Rapid increases in particular tests may be supported by evidence-based guidelines, but these are often vague about who should be tested, how often, and for how long. Substantial regional variation in test use may reflect uncertainty about diagnostic accuracy and appropriate indications for the laboratory test. There is a need for further research on the diagnostic accuracy, therapeutic impact, and effect on patient health outcomes of the most rapidly increasing and geographically variable tests.

‘I’m fishing really’ — inflammatory marker testing in primary care: a qualitative study

“… 1 , 2 Testing rates have since significantly increased: CRP testing in the UK rising by 85.8% between 2005 and 2009. 3 Large regional variations in testing rates have been noted, particularly with regard to PV. 3 This could reflect different regional policies, but may indicate that GPs are uncertain about the appropriate use of these tests.…”

“… 3 Large regional variations in testing rates have been noted, particularly with regard to PV. 3 This could reflect different regional policies, but may indicate that GPs are uncertain about the appropriate use of these tests. There is also considerable inter-practice variation in GPs’ responses to abnormal inflammatory markers.…”

Using clinical practice variations as a method for commissioners and clinicians to identify and prioritise opportunities for disinvestment in health care: a cross-sectional study, systematic reviews and qualitative study

“…Similar studies of unplanned admissions, 70 diagnostic tests, 71 referral, prescription rates 72 and other process measures 45 will be useful in identifying other aspects of health care where uncertainty manifests through variation. We chose hospital procedures because there are a nationwide routine data set and a financial incentive for hospitals to document procedures.…”

Presentation of Diagnostic Information to Doctors May Change Their Interpretation and Clinical Management: A Web-Based Randomised Controlled Trial

“…Accurate diagnosis is fundamental to the provision of appropriate health care. The volume of diagnostic tests performed in the UK National Health Service (NHS) has increased dramatically in recent years due to technological innovation and an ageing population [ 1 ]. Doctors order diagnostic tests for a variety of reasons other than for making a diagnosis [ 2 ].…”