Early undifferentiated connective tissue disease. II. The frequency of circulating antinuclear antibodies in patients with early rheumatic diseases.

The presence of antinuclear antibodies (ANA) in the serum is a common finding in various connective tissue disorders, but usefulness of these antibodies in making diagnoses or prognoses is not known. We report the results of a panel of ANA determinations including ANA, anti-dsDNA, Sm, RNP, SSA, SSB, Jo-1, Scl-70 and PM-1 in 410 patients in a 5-year descriptive study of 410 patients with rheumatic disease symptoms of less than one year's duration. While some patients met diagnostic criteria for a specific rheumatologic diagnosis, others were classified as undifferentiated connective tissue disease (UCTD) and were subclassified by a constellation of symptoms. Our results show that ANA is sensitive in systemic lupus erythematosus (SLE) and progressive systemic sclerosis even in early disease but is not specific. Other "specific" autoantibodies were seen most frequently in SLE but were relatively insensitive and were seen in low frequency in UCTD. ANA have limited diagnostic value in patients with early disease. The prognostic value of these tests will be assessed as the prospective study of these cohorts progresses.