The assessment of joint erosion via ultrasound detected more patients with erosive rheumatoid arthritis (RA) compared with radiography, according to study results published in the European Journal of Radiology. Sensitivity was good, and specificity was excellent, according to researchers.
Researchers sought to determine the thresholds for diagnosing erosive RA vs osteoarthritis using musculoskeletal ultrasonography. Investigators evaluated sensitivity, specificity, and agreement with erosive RA diagnosis based on radiography.
The study cohort included 168 consecutive patients hospitalized between 2005 and 2016 with suspicion of RA. For inclusion, patients were required to fulfill the American College of Rheumatology 1987 criteria and/or the American College of Rheumatology/European League Against Rheumatism 2010 criteria. Patients with osteoarthritis served as a control group. In addition to ultrasound, laboratory values for C-reactive protein, erythrocyte sedimentation rate, rheumatoid factor, and anticitrullinated peptide antibody titers were assessed.
The RA group included 72.6% of the patients; these participants were separated into groups based on either early or late RA (n=32 and n=90, respectively). The osteoarthritis group included 46 patients. Gender, age, and demographic characteristics were similar across both groups.
Across 168 exams, 58.9% matched between 2 readers for the number of eroded joints less than or equal to 3. Sixty-nine patients (41.1%) required a third reader; these patients were statistically younger (53.1±11.2 vs 58.8±13.6; P =.0035).
Twelve patients in the osteoarthritis group and 72 in the RA group presented with at least 1 erosion. Per radiography evaluation, 29 and 272 eroded joints were identified in the osteoarthritis and RA groups, respectively. The mean Van der Heijde–modified Sharp scores for erosions were significantly different between these groups (5.98±11.09 vs 1.09±2.58), as well as between the total population and the early and late RA groups.
Within the total patient population, 26.1% and 77.9% of patients in the osteoarthritis and RA groups, respectively, demonstrated erosions. Twelve patients in the osteoarthritis group presented with 1 erosion, whereas 5 patients had a grade 2 erosion. In the RA group, erosion distribution prevailed independently of disease duration, with the metatarsophalangeal (MTP) 5 joints experiencing the most frequent erosions (46.5%) and metacarpophalangeal (MCP) 5 joints experiencing the least (14.7%). In early RA, MCP2, MCP5, and MTP5 joints were “discriminant to establish a diagnosis of erosive RA” on ultrasound.
The presence of 2 eroded joint facets and the presence of at least 1 grade 2 erosion presented the best compromise in terms of sensitivity and specificity (68% and 100%; 72.1% and 89.1%, respectively). Eighty-three patients in the RA group and no patients in the osteoarthritis group satisfied the definition of erosive RA based on the presence of at least 2 ultrasound-identified eroded joint facets. Ultimately, 42 patients in the RA group and 5 in the osteoarthritis group satisfied the European League Against Rheumatism 2013 definition for erosive RA. Agreements between radiographic and ultrasound diagnoses, according to 2 ultrasound thresholds, were 90.4% and 92.8%, respectively.
One study limitation of note is the limitation of the use of ultrasound examination, as not all joints can be assessed in clinical practice.
“[U]ltrasound examination and radiography should be performed together in order to optimize the diagnosis of erosive disease,” the researchers concluded.
Roux C, Gandjbakhch F, Pierreisnard A, et al. Optimization of ultrasonographic examination for the diagnosis of erosive rheumatoid arthritis in comparison to erosive hand osteoarthritis [published online June 18, 2019]. Eur J Radiol. doi: 10.1016/j.ejrad.2019.06.003