The causes and clinical significance of fever in systemic lupus erythematosus: a retrospective study of 487 hospitalised patients.

The causes of fever in systemic lupus erythematosus (SLE) are complicated. Differential diagnosis of fever in SLE is crucial for optimal management of these patients. To better understand the causes and characteristics of fever in SLE, the medical records of 1949 consecutive patients hospitalised for SLE from January 2002 to May 2007 were reviewed. A total of 487 SLE-hospitalised patients with fever were identified and retrospectively analysed. Among them, 265 patients had fever from infection, 206 had fever related to SLE, 8 had fever caused by both SLE activity and infections, 4 had fever caused by malignancies and 4 had fever ascribed to miscellaneous causes. The most common sites of infection were the respiratory tract (62.6%), urinary tract (8.6%), skin and mucosa (8.3%). A prednisone dose of <or=100 mg/d was able to suppress SLE fever in 80.6% of the patients, usually within 1-5 days. Compared to patients with infection fever, those with SLE fever were more likely to have lower serum complement C3 and a higher SLE Disease Activity Index score. Infection fever was found to be associated with the use of azathioprine within the last six months. In conclusion, infection and disease activity are the most common causes of fever in SLE. Those patients for whom SLE fever could not be suppressed by a higher dose of steroids usually had severe lupus encephalopathy or hemophagocytic syndrome.