Secondary Sjogren's syndrome in systemic lupus erythematosus defines a distinct disease subset

Sjögren's syndrome (SS) may occur in patients with systemic lupus erythematosus (SLE). We sought to determine whether the presence of SS in a large cohort of patients with SLE defines a subset with distinctive sociodemographic, clinical, and laboratory features.

The Johns Hopkins Lupus Cohort was divided into 2 groups, based on the presence or absence of SS, defined by the presence of an objective measure of sicca or an abnormal minor salivary gland biopsy in a patient with sicca symptoms. These groups were compared with regard to sociodemographic, clinical, and laboratory features. Multivariable logistic regression was then performed to adjust the findings for potential sociodemographic, clinical, and laboratory confounders.

The 259 patients with SS (14% of the cohort), when compared with the 1531 patients without SS, were older at the time of SLE diagnosis and were more commonly women and white. Photosensitivity, oral ulcers, Raynaud's phenomenon, anti-Ro antibodies, and anti-La antibodies had a significant positive association while renal disease, anti-ribonucleoprotein (RNP) antibodies, and anti-dsDNA antibodies had a negative association with the presence of SS after adjustment for age (at last cohort visit), gender, ethnicity, and anti-Ro antibodies. The older age at diagnosis of SLE among the patients with SS did not remain a significant finding after adjustment for the age of the patient at last cohort visit.

The subset of patients with SLE and SS has a distinct clinical and laboratory phenotype, with a higher frequency of older white women with photosensitivity, oral ulcers, Raynaud's phenomenon, anti-Ro antibodies, and anti-La antibodies and a lower frequency of renal disease, anti-dsDNA antibodies, and anti-RNP antibodies.