Study: Ultrasound Offers Early Clues Into Development of Inflammatory Arthritis

Diagnosing inflammatory diseases such as rheumatoid arthritis early and initiating treatment with disease-modifying anti-rheumatic drugs is important in slowing disease progression and joint damage. However, it has been difficult for clinicians to identify which patients with joint pain will develop inflammatory arthritis (IA) prior to the clinical appearance of inflammation of the synovial membrane, or synovitis. A new study, published in Arthritis Research and Therapy, suggests that ultrasound technology could allow for the earlier detection of inflammation, and therefore earlier treatment of inflammatory diseases, in patients with early joint pain.

The multi-center prospective cohort study followed patients (n = 196) who had inflammatory joint complaints that could not be explained by other conditions, for a period of 1 year. Data collected at baseline and at 6-month and 12-month follow-ups included swollen joint count, tender joint count, diagnosis, medications, and laboratory values including rheumatoid factor and erythrocyte sedimentation rate.

At baseline, ultrasound examiners used a high-frequency linear array probe to evaluate 26 joints using both greyscale and power Doppler imaging, and found that 72 patients with joint pain (37%) had synovitis, as identified on the greyscale image, and 29 patients had a positive power Doppler signal. After 1 year of follow-up, 16% of patients with joint pain developed IA, and ultrasound had shown synovitis in 59% of those patients at the time of the baseline scan.

The researchers also found the following with respect to ultrasound’s predictive value:

• The positive predictive value (PPV) for developing IA if 1 joint was identified as having synovitis using greyscale ultrasound was 26%, and the negative predictive value (NPV) was 74%
• If a power Doppler signal was present for 1 joint, the PPV for a patients’ developing IA was 33%, and the NPV was 67%
• When no joints were positive for synovia using ultrasound, NPV was 89%

The authors concluded that a positive power Doppler signal is associated with the development of IA after 1 year, and that ultrasounds can also help to identify which patients with joint pain will not develop IA. Further research is necessary, they write, to confirm their results regarding the diagnostic value of ultrasound to predict progression from early joint pain to an inflammatory disease.