Extended reports
Clinical spectrum associated with positive ANCA titres in 94 consecutive patients: is there a relation with PR-3 negative c-ANCA
and hypergammaglobulinaemia ?
a Department of Internal Medicine, b and Laboratory of Immunology, c University Hospital, Leuven,
Belgium
Correspondence to: Dr D Blockmans, General Internal Medicine, UZ Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium.
Accepted for publication 20 January
1998
OBJECTIVE
To calculate the positive predictive
value (ppv) of cytoplasmic anti-neutrophil cytoplasmic antibodies
(c-ANCAs) and anti-proteinase 3 (PR 3) antibodies for Wegener's
granulomatosis (WG) and to evaluate their association with other diseases.
METHODSThe clinical files of all 94 patients who
had a positive c- or perinuclear (p)-ANCA test, or both, in the
laboratory of the University Hospital, Leuven between April 1995 and
March 1996 and who attended the Internal Medicine Department of the
hospital were retrospectively studied.
RESULTSOf the 94 patients with ANCAs
(fluorescence titre 
1/40), 57 were c-ANCA positive and 45 p-ANCA
positive (eight were simultaneously c- and p-ANCA positive). Of the 57 c-ANCA positive patients, 23 had WG. The ppv for WG thus was 40%. This
value did not increase by defining a higher threshold for a positive
ANCA. There was not a good relation between ANCA titres and disease
activity in the WG patients, nor was there a relation between anti-PR 3 antibody levels and WG disease activity. The ppv of anti-PR 3 antibodies for WG however was very high (85%). There was a positive
correlation between the level of (hyper) gammaglobulinaemia and
c-ANCA titres in those patients with final diagnoses not known to be
associated with c-ANCA. Forty five patients had positive p-ANCAs. The
largest group were those with inflammatory bowel disease (n = 20, of whom the majority had colitis ulcerosa or primary sclerosing
cholangitis, or both); the great majority of these patients had no
anti-myeloperoxidase antibodies. Vasculitis was present in eight
patients, of whom two had WG (both were also c-ANCA positive).
CONCLUSIONThere is a low ppv of c-ANCAs for WG,
caused by a high percentage of PR 3 negative, positive c-ANCA
determinations, possibly related to hypergammaglobulinaemia. Anti-PR 3 antibodies have a high ppv for WG. However, neither c-ANCA titre, nor
the level of anti-PR 3 antibodies correlated with the activity of the disease.
© 1998 by Annals of the Rheumatic Diseases
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