To determine the clinical symptoms and the panel of autoantibodies of patients with early undifferentiated connective tissue disease (UCTD) followed for at least 1 year.
716 UCTD patients with manifestations suggestive but not diagnostic of specific connective tissue disease (CTD) were recruited and followed up between 1994-1999. The patients with early UCTD were subdivided into those with isolated Raynaud's phenomenon (RP) (50 patients), unexplained polyarthritis (31 patients) and "true" UCTD (665 patients). UCTD was diagnosed on the basis of clinical manifestations suggestive of a connective tissue disease and the presence of at least one non-organ specific autoantibody. The patients' sera were tested for anti-nuclear (ANA), as well as for nine different specific autoantibodies (anti-dsDNA, -Sm, -RNP, -SSA, -SSB, -Scl-70, -centromere, -Jo1 and -PM-Scl).
The most common clinical manifestations of UCTD included RP, arthritis/arthralgias, pleuritis/pericarditis, sicca symptoms, cutaneous involvement (photosensitivity, rash), central nervous symptoms, peripheral neuropathy, fever, vasculitis, less pulmonary involvement and myositis. 230 of the 665 true UCTD patients (34.5%) developed a defined CTD (28 systemic lupus erythematosus [SLE], 26 mixed connective tissue disease [MCTD], 19 progressive systemic sclerosis [PSS], 45 Sjögren's syndrome, 3 polymyositis/dermatomyositis [PM/DM], 87 rheumatoid arthritis [RA], and 22 systemic vasculitis. 435 of 665 patients (65.4%) remained in the UCTD state, and 82 of 665 patients (12.3%) achieved complete remission with symptoms not reappearing within the 5-year period. The highest probability of evolution to a defined CTD was during the first 2 years after onset: of 230 UCTD patients 183 (79.5%) developed major organ symptoms and signs. In particular skin and cardiac complications seemed to spread during the follow-up period in those patients who progressed to SLE. The condition of 18/50 patients with isolated RP evolved to UCTD and 3 of 31 patients with unexplained polyarthritis progressed to definite CTD (2 patients RA and one MCTD).
In our study most of the UCTD patients did not develop a definite CTD, but during the follow-up period we found new clinical and serological manifestations. One-third of the UCTD patients showed progress into different types of specific CTD.