Diagnostic imaging tests ordered by GPs increase forty-five per cent

Higher cost CT and MRI scans are increasingly replacing the humble X-ray, study finds.
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01.Technology puts pressure on Medicare


Diagnostic imaging tests ordered by GPs increased by 45% over a 10-year period, according to a study of almost 10,000 GPs by University of Sydney researchers. 

The increase was explained by more GP visits, a rising number of problems managed at consultations, and a higher likelihood that GPs will order imaging tests for these problems.

Diagnostic imaging tests were ordered for about one in 10 GP visits at the end of the study period. 

The most common imaging tests ordered in the study were X-rays (54%) and computerised tomography (CT) scans (36%), with magnetic resonance imaging (MRI, 5%) and ultrasound (3%) less common. Over the study period, the use of X-rays decreased in favour of CT scans, which increased by 25%, and MRI, which doubled – albeit from a low base.

While MRIs don’t have the same radiation risks as X-rays and CT scans, these weren’t widely used by GPs as they weren’t covered by Medicare and had to be funded privately – though this changed after the study ended. This is good news for patients, who’ll benefit from less exposure to radiation, though MRI is still 15-20% more expensive than CT in a high-volume public facility (and up to 50% more for private facility).

Increased costs to Medicare

This shift to more expensive technologies is associated with an increased cost to Medicare – while the number of tests (ordered by all types of medical practitioners) increased by around 50% over the 10 years covered by the study, the costs more than doubled from $1.17bn to $2.53bn.

GPs were more likely to order imaging for musculoskeletal problems, male and female genital disorders, urinary problems, neurological disorders and pregnancy and family planning. The likelihood of diagnostic imaging tests being ordered increased with the number of problems a patient had, and for new patients.

GPs 'too quick' to order imaging tests for back problems

"Most imaging tests ordered by GPs comply with expert guidelines," says the report’s lead author, Dr Helena Britt. "However, the study indicates that GPs are too quick to order imaging tests during their initial assessment of back problems. GPs are twice as likely to order an imaging test during the initial examination of new back-problems compared to follow-up consultations.

"Expert guidelines advise caution in ordering tests for presenting back problems unless there is a 'red flag' to prompt investigation,” says Dr Britt. "'Red flags' can include issues such as major trauma, unexplained weight loss, unexplained fever, history of malignancy, inflammatory conditions and neurological issues." However, she points out, such patients account for only a small proportion of people presenting with new back problems, suggesting some unnecessary use of imaging tests.

Other research has found that for uncomplicated lower back pain, the risks from imaging radiation may outweigh the benefits, as it doesn’t improve the outcomes of treatment and may result in inappropriate treatment.

To avoid unnecessary radiation exposure, CHOICE recommends that if CT scans and X-rays are ordered you ask if it will change the way your condition is managed, or prevent a more invasive procedure, like exploratory surgery.

Also ask about alternatives – MRI is best for bones, joints, tendons, the spine and brain tumours, while CT is best for the lungs and chest cavity in general – though it delivers 400 times the radiation dose of a chest X-ray, which may suffice.

See our article on medical imaging for more.



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