Sacroiliitis in systemic lupus erythematosus The rates of involvement of the forgotten joint

Objective Although musculoskeletal system involvement is a well-known manifestation in systemic lupus erythematosus (SLE), the probability of sacroiliac joint involvement and its effect on patients might be ignored. The aim of the study was to investigate the association between SLE and sacroiliitis and to evaluate the relationship between clinical parameters and sacroiliitis in SLE. Methods The study was designed as a case-control study. A total of 63 patients with SLE and 31 age- and sex-matched healthy controls were included in the study. The clinical and demographic variables of the study population were documented. The sacroiliac joints of patients and controls were evaluated with sacroiliac magnetic resonance imaging. Human leukocyte antigen (HLA) B27 was assessed using flow cytometry (Beckman Coulter Navios-model 3, Beckman Coulter Inc., Brea, CA, USA). Multinomial logistic regression analysis was used to determine the clinical risk factors related to sacroiliitis. Results Among the 63 patients, acute sacroiliitis was found in 25 patients (39.7%) and chronic sacroiliitis was found in 21 patients (33.3%). Sacroiliitis was higher in patients than in controls (p= 0.001). Acute sacroiliitis was more frequently observed in patients when compared with the control group (p= 0.001). Higher C-reactive protein (CRP) concentrations (odds ratio= 1.75, 95% confidence interval: 1.30-2.35;p< 0.001) were found to be a risk factor for acute sacroiliitis. Conclusion The ratio of sacroiliitis was higher in patients with SLE than in controls. Increased CRP concentrations were determined as a risk factor for acute sacroiliitis. Thus, one should keep in mind that patients with SLE and higher CRP concentrations may have sacroiliitis.