The role of ultrasound in 2020

7 minute read

In 2016, two pivotal studies of rheumatological ultrasound provided reason to consider the role of ultrasound in the rheumatology clinic of 2020.

In 2016, two pivotal studies of rheumatological ultrasound provided reason to consider the role of ultrasound in the rheumatology clinic of 2020. 

The studies both compared the current “best practice” approach of treat-to-target using DAS against an ultrasonographic treat-to-target approach. The interventions and endpoints in these studies were ambitious. 

The ARCTIC study had 13 assessments over 24 months and was powered to demonstrate an absolute difference of 20% between groups meeting sustained DAS44 remission (<1.6) between 16 to 24 months.  Only 22% and 19% reached the primary endpoint; a difference of 3%, a negative primary endpoint. The ultrasound arm was associated with an increase in biologic and parenteral steroid therapy, although this was not associated with an increased rate of adverse events.

The TaSER study performed assessments three-monthly for 18 months and was powered to demonstrate a between-group difference in the mean change in DAS44 of 0.55, approximately half of a clinically significant change. While the TaSER study similarly didn’t meet its primary endpoint, significantly more patients in the ultrasound-group met DAS44 remission at 18 months.

These two negative studies have fuelled the voices of ultrasound sceptics who have claimed that ultrasound is unnecessary in the rheumatology clinic and may lead to overtreatment. 

However, these studies were never designed to demonstrate the place of ultrasound in the rheumatology clinic of 2020.

They were designed to answer a specific question: Does the addition of ultrasound to DAS at every time point improve DAS outcomes, in the setting of an intensive assessment schedule utilising current best practice of treat to target?

The results weren’t surprising to many sonographers and were actually reassuring; we simply don’t have the resources to apply ultrasound in this way. More importantly, we understood these studies were not designed to understand the place of ultrasound in the rheumatology clinic of 2020.

So, what is the role of ultrasound in the rheumatology clinic of 2020? 

The science tells us that ultrasound is a valid and sensitive technique to detect joint pathology. It is more sensitive and specific to the presence of synovitis and tenosynovitis than clinical examination and performs well compared with MRI; remember conventional radiography cannot be used to demonstrate synovitis.

Additionally, ultrasound is able to demonstrate changes in synovitis over time, indicating a response, or lack of response, to therapy.  Ultrasound is more sensitive to the presence of bone erosions and osteophytes than conventional radiography, and can detect erosions with accuracy compared with MRI. Ultrasound is able to detect smaller erosions in earlier disease than conventional radiology and has also been able to demonstrate erosive change with time. 

Science tells us that in the rheumatology clinic, ultrasound can alter the site-specific and/or systemic diagnosis in a significant proportion of patients and that translates to altered management plans.

In the rheumatology clinic, ultrasound is able to identify individuals at risk of developing an inflammatory arthritis, and those with a poor prognosis. Synovial inflammation detected by ultrasound is a risk factor for developing a persistent inflammatory arthritis requiring therapy.

Ultrasound-detected inflammation also predicts progression of structural damage in people with RA who clinically appear to be quiescent.  Similarly, an absence of ultrasound-detected inflammation predicts those in whom therapy can be withdrawn without inducing a clinical flare. 

So, while ARCTIC and TaSER have demonstrated that not all patients with early inflammatory arthritis require an ultrasound at every appointment, it is likely some will benefit from the information clinicians can obtain from performing a rheumatological ultrasound.

Unfortunately, the evidence doesn’t currently allow us to understand which patients with inflammatory arthritis will achieve better outcomes if we utilise ultrasound to guide their diagnosis and management.

Ultrasound has utility in the rheumatology clinic beyond inflammatory arthritis.

Recently, the European League Against Rheumatism (EULAR) published evidence-driven consensus guidelines recommending early imaging in patients with suspected Giant Cell Arteritis (GCA) and recommend ultrasound should be the first-line diagnostic modality.

Current Australian guidelines (eTGA) recommend temporal artery biopsy for diagnosis, because it is specific, and may “help avoid unnecessary long-term treatment (and its associated toxicities)”.

However, Australian evidence suggests temporal artery biopsies are prone to sampling errors, likely to be adversely affected by prior therapy, are usually negative, are invasive, costly and most importantly, don’t alter management.

While the Australian temporal artery ultrasound validity and reliability data is poor, it is also relatively limited. International evidence suggests that validity and reliability is not only acceptable, but that “fast track GCA” clinics (one-stop shops involving both clinical assessment and temporal artery ultrasound) result in almost a 40% reduction in the rate of temporal artery biopsies, and tripling of the rate of positive biopsies, and an 80% reduction in visual loss. 

Similarly, ultrasonography of muscle, salivary glands, skin, cartilage and lungs in rheumatic conditions is under investigation. In the rheumatology clinic of 2020, we may be performing ultrasound on much more than just inflamed joints. 

The science is incomplete, but the art of good medicine requires us to reach beyond science. Aristotle proposed physicians need to apply practical reasoning based on science, but also on experience and judgment.

In my experience and judgment, the practice of ultrasound in my clinic has benefits that are difficult to measure.  While unsupported by science, I believe I better understand the physical way in which an individual’s disease affects them, and this directs my management decisions.

Performing ultrasound forces me to slow down, and spend time with the patient. It forces me to touch them, and acts as a visual foundation for discussion of disease, therapy and response to therapy.

Carl Honoré, in his 2010 book In Praise of Slowness, explores the concept of slow medicine. He recognises that doctors are increasingly under pressure to deal with patients quickly, and writes of complementary medical practitioners who “talk to and touch the patient.

It may sound trite, but in a world here everyone is constantly dashing around, and real connections between people are few and far between, a little tender loving care goes a long way. It may even trigger healing mechanisms in the body”. 

There is however much misconception about the role of rheumatological ultrasound; it’s important to acknowledge it has limitations.

For example, there is not good evidence that using ultrasound to guide injections improves the analgesic efficacy of steroids in any disease, and in the setting of osteoarthritis, ultrasound-detected inflammation does not predict steroid response.

Another major issue is that it is incredibly user-dependant. For example, the double contour sign, widely regarded as highly specific for gout, has highly variable published reliability and is prone to misinterpretation and observer error. Rheumatological ultrasound is undoubtedly a practical skill that requires significant amounts of training and ongoing education.

The equipment is relatively costly compared to other items found in the rheumatology clinic and is associated with ongoing costs of maintenance and consumables.

Billing Medicare involves ongoing and onerous regulatory requirements, and necessitates equipment upgrades every
few years.

Performing ultrasound in the rheumatology clinic is unlikely to be financially rewarding.

The alternative to clinician-performed ultrasound (referring the patient to a radiological practice) isn’t optimal from the patient’s perspective. It involves third party appointments, diagnostic and thus management delays, and the potential for additional costs.

Notwithstanding the previously described benefits of performing ultrasound myself, I find interpreting reports of ultrasound done by a third party akin to taking a history through interpreter; much seems lost in translation. 

When I was originally asked to imagine the rheumatology clinic of 2020, it was in a wider context than office-based ultrasound. I thought about what my clinic might be like; I imagined that we’ll have some new therapies for inflammatory disease, and the indications for current therapies are likely to have been expanded. We may understand a little more about the role of the microbiome, obesity and perhaps other environmental factors in the development of autoimmunity; but in practical terms I think little will have changed in how we manage our patients.

In my rheumatology clinic in 2020, I’m unlikely to performing microbiome swabs routinely, but I’m pretty confident I’ll still be performing ultrasound.

Dr Helen Keen is Consultant Rheumatologist
at Fiona Stanley Hospital, and UWA

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