ACR2013: Joints erode in systemic lupus erythematosus and primary Sjӧgren’s Syndrome. But French researchers say their MRI studies don't justify classing them as erosive disorders like rheumatoid arthritis.
Joints erode in systemic lupus erythematosus (SLE) and primary Sj?gren’s Syndrome (pSS), but French researchers say these disorders can’t be classified as erosive diseases like rheumatoid arthritis (RA).
Prediction of erosions is important, even in sicca syndrome patients, in order to characterize patients and monitor them to tailor treatment, because bone erosions and joint space narrowing lead to joint destruction and loss of function, said Frdrique Gandjbakhch MD at the recent 2013 meeting of the American College of Rheumatology in San Diego.
Gandjbakhch was lead author of an observational study at two university rheumatology departments, looking for signs of bone erosions and joint space narrowing on MRI images from 90 patients with SLE, pSS, and RA seen between 2009 and 2011 and from controls unaffected by rheumatic disease.
“MRI is more sensitive than x-ray to detect joint erosions," said Gandjbakhch,"and may show at the same time inflammation and other features of joint disease, and is quite useful,” .
In fact, 83% of the RA patients showed erosions even on X-rays (which were among inclusion criteria), while all the SLE and pSS patients had normal X-rays of hand and feet.
Using a dedicated musculoskeletal MRI system, the investigators took images of metacarpal phalanges two to five and the wrist of the dominant hand from all patients -- SLE (n=21), pSS (n=19), RA (n=30), and Controls (n=90). To evaluate erosions and osteitis according to the definitions set by OMERACT (the Outcome Measures in Rheumatology Consortium), the images were taken in the coronal and axial planes without contrast , and adapted to differentiate between a physiological cortical break (i.e. vascular foramen) and erosion due to a pathological process.
Frequencies and scores for erosion and for osteitis were statistically different between RA and SLE/pSS, but not between SLE/pSS patients and controls.
“Although bone erosions can be observed on MRI in SLE and Sj?gren’s, they were different in size and location from RA, as well as in pathologic and physiologic characteristics," concluded Gandjbakhch. "So we cannot consider them erosive diseases similar to RA,”