FOLLOW-UP OF 151 PATIENTS WITH HIGH-TITER U1RNP ANTIBODIES

We performed a longitudinal follow-up study of clinical findings in 15 1 patients,vith high-titer antibodies against U1 ribonucleoprotein (U1 RNP) as measured by haemagglutination, Formal connective tissue diseas e (CTD) diagnoses were assigned and diagnostic transitions analysed. O ne-hundred eighteen females and 33 males entered the study; the mean d uration of follow-up was 7.1 years. Mean age at entry was 34.7 years; 73% of the patients had early disease (duration <2 years). Fifty-six p atients (37%) presented with a definite diagnosis, most often mixed co nnective tissue disease (MCTD, n = 40), followed by systemic lupus ery thematosus (SLE, n = 11) and systemic sclerosis (SSc, n = 5), Of 84 pa tients (56%) presenting with nonspecific symptoms of possible, ''undif ferentiated'' CTD, 58 developed MCTD, 4 SSc and 2 SLE. By the end of t he follow-up period, 127 patients had developed a well-defined CTD; fi nal diagnoses were: MCTD (n = 97), SLE (n = 18), SSc (n = 12). We conc lude that CTD in the context of high-titer anti-U1RNP antibodies may b e transitive and sequential in nature, although the diagnostic criteri a for MCTD previously proposed by our group seem to delimit a clinical ly stable condition in most patients in this subgroup.