Prevalence of Sjögren's syndrome in autoimmune diseases.

Investigations were carried out in 122 patients in order to identify features of Sjögren's syndrome (keratoconjunctivitis sicca and xerostomia). There were 78 patients with autoimmune diseases (rheumatoid arthritis 21, scleroderma 16, sicca syndrome 16, primary biliary cirrhosis 14, and other autoimmune disorders 11), 11 patients with chronic liver disease other than primary biliary cirrhosis, and 33 patients with a variety of non-autoimmune conditions or no obvious disease. Keratoconjunctivitis sicca was diagnosed by Schirmer's test and rose bengal staining. The oral component was diagnosed by labial biopsy and salivary scintigraphy. Forty nine patients had a definite Sjögren's syndrome, and 77 patients had the syndrome definitely or probably. Definite Sjögren's syndrome occurred in 62% of patients with rheumatoid arthritis, in 69% of patients with scleroderma, and in 71% of patients with primary biliary cirrhosis. Sjögren's syndrome was not present in any of the patients with non-autoimmune conditions. These results show that in an unselected group of patients with Sjögren's syndrome the prevalence of rheumatoid arthritis (26%), scleroderma (22%), sicca syndrome (22%), and primary biliary cirrhosis (20%) is similar. Also the occurrence of Sjögren's syndrome in primary biliary cirrhosis is even higher than that in rheumatoid arthritis.