Ultrasonography of the salivary glands in the diagnosis of Sjögren’s syndrome secondary to rheumatoid arthritis – a probabilistic approach

Introduction and aim. To evaluate the role of salivary gland ultrasound (SGUS) in differentiating rheumatoid arthritis (RA) patients with or without Sjogren’s syndrome (SS) using a probability method and to study the relation between secondary SS (sSS) and RA disease characteristics. Material and methods. One hundred RA patients with disease duration ≥5 years underwent detailed history taking, examination, routine laboratory testing, Schirmer’s test, unstimulated salivary flow rate and SGUS of the 4 major salivary glands using Salaffi and Outcome Measures In Rheumatoid Arthritis Clinical Trials (OMERACT) scores. Results. Patients sum with probabilities for sSS ≤20% and ≥80% were (39/100) before and (90/100) after SGUS with a highly significant difference (p<0.001).There was significantly more frequent carpal tunnel syndrome (CTS), longer RA disease duration and higher anti-cyclic citrullinated peptide antibodies (anti-CCP) in RA patients with sSS compared to those without (p<0.05). There was highly significant agreement between Salaffi and OMERACT scores in gland evaluation by kappa test. The highest ultrasound OMERACT score of SG showed significant positive correlation with