Lax screening methods lead to unnecessary and expensive imaging

Millions of back pain patients around the world risk being sent for unnecessary and expensive x-rays and MRIs due to screening methods that are too lax, an Australian study has found.

The study, led by PhD student Aron Downie of The George Institute, the University of Sydney and published in the British Medical Journal, says screening tests designed to identify patients in need of imaging are too loose. For every 25 patients given x-rays or MRI scans for lower back pain, only about one is found to have serious issues.

Back pain is Australia’s leading cause of disability, and a major cause of disability around the world, leading to significant health care expenditure.

Senior author Professor Chris Maher, head of the Musculoskeletal Division at The George Institute, the University of Sydney, said: “International guidelines must be streamlined and standardised”.

"Currently, doctors are advised to refer patients with lower back pain for imaging if they answer yes to key questions about their medical history – referred to as “red flags”.

Professor Maher says a major part of the problem is that although the review found 53 different red flags many of these did not accurately indicate the potential for a serious problem.

Some guidelines recommended immediate referral if any red flag was present. “For example, the Diagnostic Imaging Pathways provides a large list of red flags and directs clinicians to image patients when any single red flag is present. If this advice were to be followed, it would lead to substantial and arguably unwarranted referrals for imaging, as some of the endorsed red flags are both very common and uninformative (for example presence of thoracic pain)."

Professor Maher says data shows that in 2009-2010 there were about 3.9 million GP visits relating to lower back problems in Australia.

Another Australian study, says Professor Maher, found that one quarter (25.3%) of GP patients with lower back pain were sent for imaging. However in primary care, patients who present with low back pain are very unlikely to have cancer or fracture as the cause of their low back pain, at the rate of about one per cent.

“Clinicians naturally worry about false negatives - missing the disease - but as the diseases we are screening for in this scenario are rare, false negatives are also quite rare. People tend to forget about the issue of false positives. The downside of unnecessary testing is extra cost, radiation exposure and you worry the patient unnecessarily.”

Professor Maher has been working for the past year with the Royal Australian and New Zealand College of Radiologists, rheumatologist Associate Professor Michelle Leech, and radiologist Professor Stacy Goergen to develop education modules for medical students about appropriate imaging in patients with acute low back pain.

Professor Goergen, Director of Research at the Department of Diagnostic Imaging, Monash University, agrees on the need for streamlining the red flag system. She says private patients in Australia could be paying millions for imaging they do not need, at up to $300 for an MRI. Taxpayers are footing the bill for millions more, with the Government paying $180 for every lumbar spine MRI.

In addition, she says, while some negative consequences from unnecessary imaging might be obvious, such as opportunity costs for other patients who might be trying to access imaging services when these are limited or constrained, such as in a public hospital, other consequences are not often considered by GPs. These include incidental findings, such as a simple kidney cyst that is of no importance, that can trigger more needless tests, costs and worry for patients.

“Studies in Australia, the US and the UK are reasonably consistent in indicating that most imaging performed in patients with acute low back pain does not change diagnosis or treatment. Patients often think that imaging in non-specific lower back pain will provide an answer or diagnosis for the pain, but this is generally not the case for patients seen by GPs,” said Professor Goergen.

The study recommends an approach that involves clinical risk assessment of the patient with acute low back pain to enable better estimation of the probability of serious disease when making decisions about the need for and timing of imaging.

Professor Maher says: “Our results suggest that many guidelines will need revision so that they provide advice for practice that is more firmly grounded in the relevant diagnostic research.

“The good message for practising clinicians and students is that there is no need to remember all those 53 different red flags because many of them have no value.“