MIAMI – Ultrasound-detected enthesitis was associated with both destructive and bone formation lesions on radiography of peripheral and axial joints in a study of 222 patients with psoriatic arthritis. But its lack of correlation to clinically detected enthesitis in this study and in others has made its clinical usefulness somewhat controversial.
“This is not first time we see this result in the literature,” Ari Polachek, MD, said when presenting the research at the annual meeting of the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA). The findings suggest ultrasound reveals something different than a physical examination does, and because it’s more sensitive and specific, ultrasound is more accurate, he said.
Some differing opinions arose during a discussion after Dr. Polachek’s presentation. “When you look at the enthesitis measures [with ultrasound] ... you don’t necessarily measure the same enthesitis points you measure in clinical practice,” said Dafna D. Gladman, MD, a senior scientist at Toronto Western Hospital’s Krembil Research Institute and a rheumatologist at the University of Toronto. “We have to be careful. I don’t think we should immediately cancel the relationship between the ultrasound and clinical exam.”
“Well, I disagree entirely,” said Philip Helliwell, DM, PhD, senior lecturer in rheumatology at the University of Leeds, England, and president of GRAPPA. “We have looked at the Leeds [Enthesitis Index] with ultrasound and MRI and found no significant relationship at all.” Although Dr. Helliwell said there is a possible role for ultrasound to detect enthesitis in the Achilles, “We are fooling ourselves if we are measuring enthesitis as a pathologic entity. I don’t really know what we’re measuring when we do these scores.”
“My message is you do not need to scan every patient,” Dr. Polachek said in an interview. If a physician remains unsure about the physical exam results, it can be useful. Dr. Polachek, who completed his medical training in Israel, added: “In Israel, we say that ultrasound is ‘the final judge.’ ”
Association with radiographic joint findings
The investigators achieved their study aim: demonstrating that the severity of sonographic enthesitis is a marker of radiographic peripheral and axial joint damage in psoriatic arthritis. They found an association for both destructive and bone formation lesions.
“These findings highlight the potential role of enthesitis in the pathogenesis of articular damage in psoriatic arthritis,” said Dr. Polachek, clinical and research fellow at the University of Toronto.
The researchers assessed 12 entheseal sites with ultrasound. They used the Madrid Sonography Enthesitis Index scoring system (MASEI) to determine the global extent of enthesitis in each patient. In addition, they used the modified Steinbrocker score to assess peripheral joint damage, and the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) to assess spinal damage. Patients also underwent a clinical exam and were asked about their medical history.
Multivariate analysis revealed a significant association between higher MASEI score and joint ankylosis (odds ratio, 2.09; P = .0001) and arthritis mutilans (OR, 1.73; P = .005). The total MASEI score was associated with the modified Steinbrocker score (OR, 9.3; P less than .0001) in a logistic regression analysis; total MASEI also significantly correlated with the mSASSS measure of spinal damage (OR, 1.55; P less than .0001) in a linear regression analysis.
Participants had a mean age of 56 years and a 17-year mean duration of psoriatic arthritis. They presented with a mean of 2.4 tender joints and 1.1 swollen joints. At study entry, their mean scores were 15.6 on MASEI, 18.1 on modified Steinbrocker, and 1.72 on mSASSS.
The strengths of the study included a large number of participants and control of multiple possible confounders (age, sex, body mass index, duration of psoriatic arthritis, and use of disease-modifying antirheumatic drugs and biologics). It is limited by its cross-sectional design, which rules out inferences of causality.
“Traditionally, patients came in with a tender joint, and we might not see anything. Now I can put the sensor down and say they have inflammation,” Dr. Polachek said. In such cases, he may suggest more aggressive treatment. However, if an asymptomatic patient has ultrasound findings, “right now the recommendation is not to do anything. Otherwise, it could be overtreatment.”
“This is the future,” Dr. Polachek said. “I started doing ultrasound myself – it’s a game changer.”
Dr. Polachek has received funding from Janssen and the Krembil Research Institute.