Identifying waste: diagnostic tests

February 16, 2018

Jack O’Sullivan

Healthcare systems around the world are desperately searching for ways to reduce costs. High on the agenda of health secretaries is identifying and eliminating waste. Waste can be thought of as the delivery of tests and treatments than cause more harm than good (overuse) or the failure to deliver tests and treatments that would cause benefit (underuse). Mitigating both forms of waste can help ease financial burden and prevent avoidable patient harm.

There is a paucity of evidence directly quantifying healthcare waste, especially for diagnostic tests. Tests are costly in themselves – laboratory tests account for £2.5 billion in the NHS alone – and can also have knock-on resource consequences. We set out to quantify which tests are most frequently over and underused.

What did we do?

We identified all observational studies that quantified over and under. These studies measured the appropriateness of a diagnostic test request, measured against a national or international guideline.

What did we find?

17 tests were underused >50% of the time (Figure 1). Of these, echocardiography (n=4 measures) was consistently underused. There was large variation in the rate of inappropriate underuse of pulmonary function tests (38%–78%, n=8). Eleven tests were inappropriately overused >50% of the time (Figure 2). Echocardiography was consistently overused (77%–92%). Echocardiography was consistently overused (77%–92%), whereas inappropriate overuse of urinary cultures, upper endoscopy and colonoscopy varied widely, from 36% to 77% (n=3), 10%–54% (n=10) and 8%–52% (n=2), respectively.

Strengths and weaknesses

We looked at all the available evidence and produce a useful list of tests that are commonly over and underused. Limitations to be aware of when interpreting the data include: not all tests had data quantifying over and underuse (there could be other tests, that were not measured that higher or lower rates than the ones included in our study) and our data comes from primary care setting all over the world (tests may be over or underused more or less in your own setting).


There is substantial variation in the how often GPs follow diagnostic test guidelines. Echocardiogram is consistently both under and overused. There is evidence that the ordering of echocardiogram, urinary cultures, upper endoscopy and colonoscopy could be improved.

Lastly, our methods can be used by doctors or policy makers to try and identify wasteful testing in their own setting.

 You can view the full paper at


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