Are isolated antinucleolar antibodies a marker of scleroderma?

This study was designed to determine the prevalence and positive predictive value of isolated antinucleolar antibody (ANA) in scleroderma patients. We identified 73 rheumatology clinic patients with isolated ANAs. ANA titers greater than 1:160 were considered positive. The overall prevalence of isolated ANAs was 2.9%. The prevalence of isolated ANAs in scleroderma, systemic lupus erythematosus (SLE), and rheumatoid arthritis were 20.3%, 2.68%, and 3.3%, respectively. Scleroderma and SLE were present in 12 patients (16.4%) each. Other rheumatologic disorders identified in these patients were RA (12.3%), undifferentiated connective tissue disease (8.2%), mixed connective tissue disease (4.1%), vasculitis (6.8%), fibromyalgia (8.2%), osteoarthritis (5.4%), crystal-related arthropathy (6.8%), seronegative arthritis (2.7%), sarcoidosis (4.1%), and others (8.2%). There were no statistically significant differences in the median ANA titers in scleroderma versus systemic lupus (P = 0.16) or undifferentiated connective tissue disease (P = 0.18). The median titers were higher in scleroderma in comparison with rheumatoid arthritis (P = 0.01), osteoarthritis (P = 0.007), fibromyalgia (P = 0.001), and crystal-related arthropathy (P = 0.009). Isolated ANAs have poor sensitivity (20.3%) and the positive predictive value for this test is only 16.4% for scleroderma.