SENSITIVITY AND SPECIFICITY OF THE ANTINE UTROPHIL CYTOPLASMIC ANTIBODY (C-ANCA) IN SYSTEMIC VASCULITIS

The diagnostic value of c-ANCA as a specific marker of systemic vascul itis (particularly Wegener's granulomatosis) is well established. The pronostic value of c-ANCA for determining disease activity is controve rsal. We have prospectively studied in ten patients with systemic vasc ulitis over a mean period of 34 months (extreme 2-61 months). All pati ents had c-ANCA at the moment of the diagnosis: four patients had high titer of c-ANCA all over the period study; three clinical and biologi cal exacerbations of the disease was observed without variation of the c-ANCA titer In four patients c-ANCA disappeared within 6 months afte r the beginning of the treatment correlated with disease activity. Som etimes a rise of c-ANCA titer was observed with or without disease act ivity. In one case c-ANCA titer had a serrated evolution. The sensitiv ity and the specificity of the c-ANCA for disease activity in the ten studed patients were respectively 1 and 0.28. In patients with systemi c vasculitis and c-ANCA at the time of the diagnosis, variation in c-A NCA titer alone is of limited prognostic value for predicting disease course.