Why do general practitioners take blood? A cross-sectional study of use of blood tests in UK general practice

Objectives: To describe the reasons UK general practitioners (GPs) give for taking blood, and to examine if high and low testing GPs differ in the reasons given. Methods: Cross-sectional survey of all decisions to take blood by 42 UK GPs in a four-week period. Results: The commonest 'most important' reasons to take blood were monitoring (37.6%), looking for a specific diagnosis (23.0%), and general screening/excluding anything serious (9.9%). Reassurance of the patient (16.1%) or doctor (10.8%) and uncertainty (14.4%) were commonly chosen as relevant. Multiple tests were commonly used, particularly when general screening or uncertainty were the most important reasons for testing. There were no differences between high and low testing doctors in the patterns of reasons chosen. Conclusions: The commonest motivations to test were diagnostic, but the frequent use of multiple tests, particularly for the exclusion of serious disease and when GPs are uncertain, suggests that education and feedback could improve the diagnostic use of tests. Non-diagnostic motivations to test were commonly relevant, particularly reassurance which is a legitimate aim of the consultation in general practice. Rather than simply seeing the use of non-diagnostic blood tests to achieve reassurance as inappropriate, it may be better to ask whether blood tests are effective at reassuring without unintended adverse consequences. There is a need for good research evidence of the utility of blood testing or other strategies to reassure.