Health-care resources are wasted when doctors overuse diagnostic tests. The tests may be redundant or inappropriate in the first place, and may also generate false-positive results, which prompt further needless investigation, or cause adverse effects.
Over the past decade, the use of pathology laboratory tests is thought to have increased by 5% to 10% each year. At the same time, requests for diagnostic imaging (radiology) investigations have increased by approximately 9% per year. These services now account for approximately 15% of all Medicare outlays.
It’s difficult to ascertain the proportion of diagnostic investigations that represents genuine overuse because of the problem of defining “appropriate” testing. But in hospital settings, as many as two-thirds of requests for some common pathology tests may be avoidable, because they’ve been shown to have no impact on diagnosis or management.
Still, the reasons for uncritical overuse of investigations are complex. They include inexperience, lack of awareness of the evidence base for using tests, lack of awareness of tests’ costs, patient requests, the practice of “defensive medicine” (investigating for unlikely alternative possibilities, primarily to minimise risk of later litigation), as well as various non-clinical factors such as geographical location.
In hospital settings, most test requests are submitted by junior medical officers. So there’s been support for strategies targeted at doctors in the early years of postgraduate training, which is recognised as a critical period. These have included restricting the range of testsjunior doctors may request, an approach found to be effective in emergency departments.
More broadly, management systems with budgetary controls as well as online systems with decision support have also been promoted.
Education may have a valuable role to play. Several studies indicate that education, audit and feedback can be useful in limiting demand for diagnostic investigations.
In collaboration with the Royal College of Pathologists of Australasia, my colleagues and I have developed an open-access website to educate junior medical officers about the rational use of diagnostic investigations. Users interact with simulated cases and can request investigations as they attempt to establish a diagnosis.
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As they progress through each case, they’re presented with a running tally of the costs of the tests sought. At the end, they receive feedback via comparison with what an expert senior doctor would have done.