Ultrasound helps early identification of polyarthritis

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Rheumawire

May 5, 2004

Ultrasound helps early identification of polyarthritis

Leeds, UK - One third of patients initially diagnosed as having

oligoarthritis will go on to develop polyarthritis. New research shows

that ultrasound examination may help to identify these patients early,

allowing more intensive therapy to be started sooner, UK researchers

say.

Dr J Wakefield (General Infirmary at Leeds, UK) and colleagues

report their findings in the April 2004 issue of the ls of the

Rheumatic Diseases [1]. " This study shows we can spot polyarthritis

patents earlier using ultrasound. This may have important implications

for disease management, " Wakefield told rheumawire.

Wakefield explains that oligoarthritis is an inflammatory arthritis

characterized by clinical swelling of only a few joints. Definitions are

varied, however, and range from 2 to 4 joints or less than 6. The term

encompasses a group of diseases, including reactive arthritis, psoriatic

arthritis, and undifferentiated arthritis, in addition to rheumatoid

arthritis in evolution.

Currently, a definition of oligoarthritis is based on clinical

examination alone, " but this is relatively inaccurate, " Wakefield adds.

Those identified as having oligoarthritis will generally receive

intra-articular steroid injections only, until they progress further.

Generally, some patients with oligoarthritis get better, some become

symptomatic, and some go on to develop inflammatory arthropathies. Those

who do go on to develop polyarthritis (swelling in more than 6 joints)

will require more intensive treatment with disease-modifying drugs such

as methotrexate, he says.

Together with colleagues, Wakefield set out to determine the prevalence

of subclinical synovitis defined by ultrasound in 80 patients with early

(<12 months), untreated oligoarthritis in 5 or fewer joints. The

ultrasonographer was unaware of the clinical findings and scanned all

painful joints. In addition, in the final 40 patients, a standard set of

joints was scanned to establish the frequency of synovitis in

asymptomatic joints.

There were 644 painful joints (with and without clinical synovitis)

among the 80 patients. In these joints, ultrasound detected synovitis in

79% of those with clinical synovitis and 33% of joints without

synovitis. In asymptomatic joints, the prevalence of synovitis was 13%.

" This study, for the first time, describes the ultrasound phenotype of

patients with early, treatment-naïve 'oligoarthritis,' " the researchers

say. " It highlights the relative insensitivity of routine clinical

examination and demonstrates that subclinical synovitis as detected by

ultrasound is common in these patients. Synovitis may occur in both

painful (but not clinically synovitic) joints and asymptomatic joints. "

" This will teach us to look more carefully at those joints that are

painful but not swollen, " Wakefield commented to rheumawire.

Wakefield says ultrasound represents a safe and relatively inexpensive

tool for joint examination, but " it is underused in the UK, with only

around 5 or 6 centers employing it. " The technology is used much more

widely in Europe, he adds, where it is " sold as an extension to a

clinical examination. "

And the US is even further behind. " There are only around a dozen

centers in the whole US using ultrasound, " says Wakefield, who is chair

of the American College of Rheumatology ultrasound study group.

Comparing ultrasound with magnetic resonance imaging (MRI), Wakefield

says ultrasound is much quickerit only takes about 15 minutes compared

with around 1 hour for MRIand it is noninvasive (whereas MRI often

involves gadolinium enhancement) and cheaper. In addition, MRI is

limited to predesignated anatomical areas at the time of scanning, while

with ultrasound, lots of joints can be assessed at the same time.

Nevertheless, there is no doubt that MRI is more sensitive than

ultrasound and it gives good images of cartilage and bone marrow, which

ultrasound can't do. He suggests that ultrasound be used as a " screening

tool " to help select the minority of patients who really need MRI.

" Waiting lists for MRI are also long, " he adds, " so using ultrasound in

this way ensures that only those people who really need MRI join the

waiting list. "

Nainggolan

Source

1. Wakefield RJ, Green MJ, Marzo-Ortega H, et al. Should oligoarthritis

be reclassified? Ultrasound reveals a high prevalence of subclinical

disease. Ann Rheum Dis 2004 Apr; 63(4):382-5.

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