Ultrasound Predictors for Persistence or a Change in the Diagnosis of Rheumatoid Arthritis After 5 Years—A Prospective Cohort Study of Patients with Early Rheumatoid Arthritis

<b>Aim:</b> To identify ultrasound (US) predictors of persistence or change in the diagnosis of rheumatoid arthritis (RA) after five years in a cohort of patients with early RA. <b>Patients and Methods:</b> One hundred and twenty patients with early arthritis who met the 2010 ACR/EULAR classification criteria for RA were followed for a period of five years. The US assessment at baseline included a bilateral evaluation of the wrists, second to fifth metacarpophalangeal (MCP) joints, second to fifth proximal interphalangeal (PIP) joints, the IV and VI extensor compartments of the wrists, and the flexor tendons of the second to fifth fingers. This evaluation was conducted using both grayscale ultrasound (GSUS) and power Doppler ultrasound (PDUS). The following scores were recorded for each patient: synovitis score, mini-enthesitis score (including paratenonitis of the finger extensor tendon at the MCP joint, central slip enthesitis at the PIP joint, pseudotenosynovitis, and the A1 pulley of the second finger), finger flexor tenosynovitis score, and tenosynovitis score for the IV and VI wrist extensor compartments. The receiver operating characteristic (ROC) curve was utilized to identify the ultrasound predictors for either maintaining or revising an initial diagnosis of RA. <b>Results:</b> At month 6, 82 (68%) patients were classified as having RA according to 1987 ACR RA criteria, 23 (19.2%) were diagnosed with psoriatic arthritis (PsA), 10 (8.3%) with systemic connective tissue disease (SCTD)-8 (6.7%) patients with Sjogren Syndrome and 2 (1.7%) patients with systemic lupus erythematosus (SLE)-and 5 (4.2%) patients with calcium pyrophosphate deposition disease (CPPD). The most significant predictor of RA in the fifth year was the VI extensor compartment tenosynovitis score, with an AUC of 0.915 and a criterion value > 0, associated with a sensitivity of 82.93% and a specificity of 100% (<i>p</i> < 0.001). The PDUS synovitis score demonstrated the second-best prognostic ability with an AUC of 0.823, a criterion value > 2, a sensitivity of 82.93%, and a specificity of 73.68% (<i>p</i> < 0.001). The mini-enthesitis score showed the best prognostic ability of a PsA diagnosis with an AUC of 0.998, a criterion value > 1, a sensitivity of 95.65%, and a specificity of 100% (<i>p</i> < 0.001). The paratenonitis score, pseudotenosynovitis score, and thickened A1 pulley were also predictive of PsA diagnosis with AUCs of 0.977, 0.955, and 0.919, respectively (<i>p</i> < 0.001 for all). <b>Conclusions:</b> Nearly one-third of the patients who were initially classified as having RA had their diagnosis revised at the end of the fifth year. Ultrasound of joints, tendons, and mini-entheses at baseline may serve as potential imaging predictive biomarkers for persistence or change in diagnosis after 5 years.