Diagnostic Imaging Tests Ordered by General Practitioners in Australia Nearly Double in 10 Years

A 45% increase in diagnostic imaging tests ordered by Australian general practitioners (GPs) is being fueled by increasing GP visits, an escalating number of problems managed at doctor visits, and a higher probability that GPs order imaging tests for these problems, according to a new study.

Based on a long-term national survey of 9,802 GPs between 2002 and 2012, the report pulled data from more than 980,000 GP-patient encounter records to assess the extent to which GP’s order tests in line with diagnostic imaging guidelines.

“Most imaging tests ordered by GPs comply with expert guidelines,” said the report’s lead author, Dr. Helena Britt, from the University of Sydney (Australia). “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.”

The report’s findings were presented by Dr. Megan Keaney, assistant secretary, medical specialist services branch, Medical Benefits Division, Australian Government Department of Health, at the Primary Health Care Research Conference, held July 23-25, 2014, in Canberra (Australia).

“Expert guidelines advise caution in ordering tests for presenting back problems unless there is a ‘red flag’ to prompt investigation,” noted 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, patients with red flags account for a small proportion of people presenting with new back problems.”

Overall, diagnostic radiology (standard X-rays) was the test type most frequently ordered by GPs (54%), followed by computed tomography (36%), magnetic resonance imaging (MRI) (5%) and ultrasound (3%). The study also noted a trend away from diagnostic radiology to CT and MRI orders, in line with changing recommendations in the guidelines.

The four strongest predictors of whether GPs order a diagnostic imaging test are: (1) Number of problems managed at the GP visit—each additional problem managed increases the probability of testing by 41%. (2) Type of medical problem managed—especially musculoskeletal problems, female genital issues, family planning issues, and pregnancy. (3) Patient characteristics—females, those aged 45 years and older, and new patients. (4) GP characteristics—women, GPs aged 35-44 years, those in solo practice, and those in a practice co-located with an imaging service.

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