Ultrasonography is useful to detect subclinical synovitis in SLE patients without musculoskeletal involvement before symptoms appear

The purpose of this study is to investigate the frequency of the subclinical synovitis in hand or wrist joints of the SLE patients using ultrasonography (US) and to correlate them with clinical parameters. Forty-eight systemic lupus erythematosus (SLE) patients without musculoskeletal (MS) involvement were enrolled and underwent clinical and laboratory examinations. Gray-scale and power Doppler (PD) US was performed for imaging the wrist, second and third metacarpophalangeal (MCP) joints, and flexor tendons on non-dominant sides of the individuals. US synovitis index (USSI) and PD index were calculated as sum of the synovitis and PD semiquantitative scores, respectively, obtained from each joint. Subclinical synovitis was found by US in 28 (58.3 %) out of 48 patients. US revealed synovitis of the wrist in 16 (33.3 %) patients, of the second MCP joint in 14 (29.2 %) and of the third MCP joint in 15 (31.3 %). PD signals in three (6.3 %) patients and tenosynovitis in two (4.2 %) were also detected. USSI scores showed significant positive correlation with erythrocyte sedimentation rate (ESR) levels (r = 0.30, p < 0.05) or anti-dsDNA Ab titers (r = 0.34, p < 0.05). Within 6 months after US examination, new MS symptoms were developed in 11 (22.9 %) patients. Older age at diagnosis (OR 1.283, 95 % CI 1.029–1.601, p = 0.027) or higher USSI scores (OR 12.93, 95 % CI 1.023–163.503, p = 0.048) were independently associated with development of new MS symptoms. Subclinical synovitis is common in SLE patients who do not suffer from MS symptoms. US is useful to detect joint abnormalities before symptoms appear in SLE patients.