FROM ARTHRITIS RESEARCH AND THERAPY
Ultrasound evaluations to look for subclinical inflammation in joints of patients with arthralgia appear best at ruling out inflammatory arthritis (IA) 1 year in the future rather than ruling it in, according to findings from a multicenter cohort study published online in Arthritis Research and Therapy.
The imaging modality’s ability to identify those who will not go on to develop IA complemented the serologic and clinical factors that help to discriminate the individuals with arthralgia who are most at risk of the condition.
First author Myrthe van der Ven, PhD, of University Medical Centre Rotterdam (the Netherlands) and her colleagues chose to examine the ability of ultrasound to predict IA in arthralgia patients because of its flexibility and ease of use in the clinic in comparison to MRI, which is more time consuming and expensive to use.
The ultimate goal of using imaging such as ultrasound in patients with arthralgia is to identify those who would benefit from starting treatment with disease-modifying antirheumatic drugs as early as possible to potentially improve outcomes, but it also could help to discriminate between the anti-citrullinated protein antibody (ACPA)-positive and seronegative individuals without clinical signs of inflammation at baseline who may progress from arthralgia to IA.
“Although ACPA positivity is a very good predictor for those patients who will develop IA within 1 year, it is still difficult to identify the exact individuals who will develop IA, because any ACPA-positive individual has an a priori chance of 50% of developing IA. In seronegative patients, the prediction of IA is even more difficult, because only 5% develop IA within the subsequent year. Imaging techniques have been shown to be able to detect synovitis before its clinical appearance and could be of help in identifying those at risk of IA,” the investigators wrote (Arthritis Res Ther. 2017;19:202. doi: 10.1186/s13075-017-1405-y).
Dr. van der Ven and her associates found that 31 (16%) of 196 patients who had arthralgia for less than 1 year in the hands, feet, or shoulders went on to develop IA after 1 year of follow-up. In this group of 196 patients at baseline, 72 (37%) had synovitis on ultrasound – defined as a greyscale grade of 2 or 3 and/or the presence of power Doppler signal (grade 1, 2, or 3) – including 32 with a positive power Doppler. A total of 18 patients were lost to follow-up during the first 6 months and another 19 were lost during months 6-12.
Rheumatologists who were unaware of ultrasound findings had to confirm soft-tissue swelling as arthritis at 1 year to classify it as incident IA. The positive predictive value of ultrasound for IA was only 26% when at least 1 joint out of 26 assessed was positive, but the negative predictive value when no joints were positive on ultrasound was 89%.
Overall, at 1 year, 15 of the 31 patients with IA had started therapy with a disease-modifying antirheumatic drug and 22 did not have a definite diagnosis; 12 had monoarthritis and 10 had polyarthritis. The remaining nine patients included four with rheumatoid arthritis, four with psoriatic arthritis, and one with spondyloarthritis.
At baseline, individuals with IA were more often older (mean age 50 vs. 44 years; P = .005), had synovitis on ultrasound (59% vs. 32%; P = .007), and had a positive power Doppler signal (31% vs. 12%; P = .012). A multivariate analysis revealed that IA at 1 year of follow-up could be independently predicted according to age (odds ratio, 1.06), morning stiffness lasting more than 30 minutes (OR, 2.80), ACPA positivity (OR, 2.35), and synovitis on ultrasound (OR, 2.65).
The investigators noted that the study’s limitations relate to requirements for patients to have at least two painful joints in hands, feet, or shoulders at baseline and two criteria related to inflammation. The possible inflammation-related criteria required for entry included morning stiffness for more than 1 hour, inability to clench a fist in the morning, pain when shaking someone’s hand, pins and needles in the fingers, difficulties wearing rings or shoes, family history of rheumatoid arthritis, and/or unexplained fatigue for less than 1 year.
Rheumatologists who enrolled patients into the cohort also may have “recruited clinically suspected patients with possibly more severe symptoms,” the investigators noted. Another potential source of bias related to the group of 38 patients who chose not to participate: It’s possible these patients had less severe symptoms than those who participated in the study.
The study was funded by an investigator-initiated grant from Pfizer. The authors declared that they have no competing interests.