Predictive utility of ultrasound in a cohort of patients with clinically suspect arthralgia

To demonstrate the predictive utility of ultrasound in a cohort of patients with clinically suspect arthralgia (CSA). Prospective longitudinal study of a cohort of patients fulfilling the EULAR criteria for CSA. Exclusion criteria were: clinical synovitis on physical examination, previous treatment with DMARDs or corticosteroids, and a diagnosis of fibromyalgia or osteoarthritis. Patients were followed for 2 years, with evaluation of clinical and sociodemographic characteristics and of progression to inflammatory arthritis. An extensive blinded ultrasound examination was performed at baseline (36 joints and 14 tendon compartments), and various ultrasound scores were calculated. Descriptive and comparative analyses were performed between patients who developed clinical inflammatory arthritis and those who did not, as well as a subgroup analysis specifically for the rheumatoid arthritis (RA) subgroup. Multivariate logistic regression analysis (backward stepwise, likelihood ratio) was used to assess the predictive value of clinical and ultrasound parameters for progression to inflammatory arthritis. Of the 69 patients included (90% women), 17% were seropositive for rheumatoid factor and 13% for anti-citrullinated peptide antibody (ACPA). After 2 years of follow-up, 29 patients (42%) developed inflammatory arthritis (17% RA). The independent predictors of progression to inflammatory arthritis in the multivariate model were: subjective sensation of swelling (OR 6.292, 95% CI 1.391–28.460, p = 0.017), ACPA positivity (OR 24.527, 95% CI 2.051–293.343, p = 0.011), and global PD score (OR 1.272, 95% CI 1.065–1.519, p = 0.008). Model fit was satisfactory (Hosmer-Lemeshow p = 0.249; Nagelkerke R²=0.473; overall classification accuracy 76.6%). In ACPA-negative patients specifically ( n = 60), subjective sensation of swelling and global PD score remained independent predictors of progression to IA. Significant differences were also observed for ultrasound findings, with higher scores in both greyscale and power Doppler, especially in the wrists, proximal interphalangeal joints, and metatarsophalangeal joints. Notably, all patients with baseline erosions progressed to RA. In patients with clinically suspect arthralgia, the independent predictors of progression to inflammatory arthritis were subjective sensation of swelling, ACPA positivity, and global power Doppler ultrasound score. These findings support the combined use of clinical assessment, serological testing, and baseline Doppler ultrasound evaluation in the risk stratification of CSA patients, irrespective of seropositivity, pending validation in larger, multicentre cohorts.