To investigate salivary gland ultrasound (SGUS) abnormalities in relation to clinical phenotype and patient characteristics, disease activity, and disease damage in patients with primary Sjögren syndrome (pSS).
Consecutive outpatients included in our REgistry of Sjögren Syndrome LongiTudinal (RESULT) cohort were selected. Patients with pSS who were included were classified according to the American College of Rheumatology/European League Against Rheumatism (EULAR) criteria and underwent full ultrasonographic examination (Hocevar score 0-48) at baseline. Total SGUS scores of ≥ 15 were considered positive. Patient characteristics, disease activity, and disease damage were compared between the different SGUS groups.
In total, 172 of 186 patients with pSS were eligible, of whom 136 (79%) were SGUS positive. Compared with patients who were SGUS negative, SGUS-positive patients had significantly longer disease duration, higher EULAR Sjögren Syndrome Disease Activity Index, higher Sjögren Syndrome Disease Damage Index, and were more likely to have a positive parotid gland biopsy, anti-SSA/SSB antibodies, and abnormal unstimulated whole saliva (UWS) and ocular staining score (OSS), and higher levels of IgG and rheumatoid factor. Regarding patient-reported outcome measurements (PROM), patients who were SGUS positive scored significantly lower on the EULAR Sjögren Syndrome Patient-Reported Index for fatigue and pain, and more often found their disease state acceptable compared with patients who were SGUS negative. SGUS total score showed significant associations with various clinical and serological variables, and with PROM. Highest associations were found for UWS (ρ = -0.551) and OSS (ρ = 0.532).
Patients who were SGUS positive show a distinct clinical phenotype in all aspects of the disease compared with patients who were SGUS negative: clinical, functional, serological, and PROM. SGUS could be a helpful tool in selecting patients for clinical trials and estimating treatment need.