When the metatarsophalangeal (MTP) joints are excluded, synovial thickening on ultrasonography (US) can predict clinical arthritis development in seropositive patients with arthralgia, according to study results published in Arthritis Research & Therapy. The results indicate that US may be able to identify patients at higher risk for developing arthritis in individuals with an intermediate risk for rheumatoid arthritis (RA).
The study included participants with arthralgia who were positive for anti-citrullinated protein antibodies and/or rheumatoid factor but did not have clinical arthritis (n=163). The researchers performed US at baseline in 16 joints:
- bilateral metacarpophalangeal 2–3,
- proximal interphalangeal 2–3,
- wrist and MTP joints 2–3 and 5.
They scored the images for synovial thickening and for positive signs on power Doppler (PD).
The researchers evaluated the association between US abnormalities and arthritis development at the joint and patient level and also explored the added value of US over clinical parameters.
After a median follow-up of 12 months, 31% of participants (n=51) developed clinical arthritis. Of these, 86% (n=44) satisfied the 2010 American College of Rheumatology/European League Against Rheumatism classification criteria for RA.
Using US, the researchers found synovial thickening in at least 1 joint in 30% of participants (n=49) and with PD in at least 1 joint in 4% of participants (n=7).
When MTP joints were excluded from US assessment, synovial thickening was associated with both the development and timing of clinical arthritis in any joint at the patient level, with an odds ratio of 6.6 and hazard ratio of 3.4. The mean time to arthritis was 23 months when synovial thickening was present compared with 45 months when it was not.
The results did not indicate any association between US and arthritis development at the joint level. “Based on our data we do expect that US can be of additional use for clinicians in those patients who have an intermediate risk of developing arthritis when calculating the prediction rule, as compared to those patients for whom the risk is more clearly defined based on clinical parameters (low and high risk),” the researchers wrote.
van Beers-Tas MH, Blanken AB, Nielen MMJ, et al. The value of joint ultrasonography in predicting arthritis in seropositive patients with arthralgia: a prospective cohort study. [published online December 19, 2018.] Arthritis Res Ther. doi: 10.1186/s13075-018-1767-1769.