A US study found that displaying the cost of commonly used or expensive tests on a hospital's ordering system reduced the number requested without affecting patient care.
The tertiary care hospital participating in the research saved £400,000 in just six months.
Lead author Dr Leonard Feldman from the Johns Hopkins University School of Medicine in Baltimore, Maryland told GP the benefits could be replicated in UK primary care.
GPC clinical and prescribing chairman Dr Bill Beeby said many GPs had 'absolutely no idea' of some test costs, adding that too many tests are ordered at the same time in an attempt to accelerate diagnosis and reduce the need for patients to return to the surgery multiple times.
But it would need 'more than just a price code' to change behaviour, he said. 'You need to consider how to manage the risk differently, or the present defensive practices will continue.'
Previous research from Australia found that 67.9% of inpatient lab tests ordered over a six-month period did not contribute to patient care.
In the study, published in JAMA Internal Medicine, researchers selected 61 common or expensive lab tests ordered by clinicians at the Johns Hopkins Hospital in Baltimore, Maryland.
They randomly assigned half of these tests to display the price per test on computer order forms and half to show no prices. Over six months, clinicians ordered almost 1.2m tests.
Researchers saw a 9% fall in the number of tests ordered when price information was displayed. In contrast, numbers rose by 5.1% when price information was absent.
They said clinicians who were given prices opted for cheaper tests when these would accomplish the same goal as more expensive comprehensive tests.
Researchers said it was unclear whether extending the scheme past six months would lead clinicians to become be 'desensitised' to price information.
They assumed the decrease in tests ordered reflected cutting of waste and not rationing of care, which could prove a false economy.
Nevertheless, researchers said the practice had potential to cut inappropriate testing and waste in many healthcare settings.
Professor Feldman said: 'Our study offers evidence that presenting providers with associated test fees as they order is a simple and unobtrusive way to alter behaviour.
'In the end, we ordered fewer tests, saved money and saved patients from extra needle sticks without any negative outcomes.'
Earlier this year, Labour peer and former health minister Lord Warner said CCGs could save up to £750m to reinvest in primary care by changing how pathology services were commissioned.
The NHS is currently conducting a review into the quality of pathology services.
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