Diagnostic and prognostic significance of different antinuclear antibodies in more than 1000 consecutive Albanian patients with rheumatic diseases.

ABSTRACT

In an unselected population of 1390 consecutive Albanian patients with rheumatic diseases (RD) and other miscellaneous non-rheumatic diseases (MNRD), for whom antinuclear antibody (ANA) testing was requested, we calculated the diagnostic sensitivity, specificity and positive predictive value (PPV) of ANA positive results, ANA titres over 1100, anti-native DNA (nDNA), anti-Sm, anti-U1 RNP, anti-SSA (Ro) anti-SSB (La) and anti-non-identified extractable nuclear antigen (NIENA) antibodies. The PPVs of these ANA types were found to be appreciable only for systemic lupus erythematosus (SLE); only the positive predictive value of ANA for SLE (26.4%) was lower than that for RA (34.3%). The anti-snRNP (Sm/U1RNP) positive SLE patients were more likely to have over 4 of the ARA criteria for SLE, ANA titres over 1100, and anti-nDNA antibodies, in contrast with the anti-snRNP negative subgroup. On the other hand, the anti-ENA positive and anti-nDNA positive SLE patients generally showed higher frequencies of renal disease, over 4 of the criteria for SLE and ANA titres over 1100, compared to anti-ENA positive and anti-nDNA negative patients. Our data suggest that the association of anti-snRNP antibodies with a more severe form of SLE is not to be attributed to these antibodies themselves, but rather to their close association with the concomitant presence of anti-nDNA antibodies.