Diagnostic value of combined evaluation of neopterin and anti-DNA antibody levels for assessment of disease activity in systemic lupus erythematosus.

Objective: The present study was designed to investigate whether the combined evaluation of laboratory tests could improve their diagnostic value. Laboratory parameters of systemic lupus erythematosus (SLE), such as anti-dsDNA, neopterin, soluble IL-2 receptor (sIL-2R), C3, C4, and complement haemolytic activity (CH50), and a logistic model that provides the probable clinical activity (PCA) of a given patient, calculated by stepwise multiple logistic regression analysis from the parameters mentioned above--were evaluated as SLE activation markers.

Methods: Serum samples from 101 patients were assayed by ELISA (neopterin, sIL-2R, anti-dsDNA), radial immunodiffusion (C3, C4) and haemolytic complement assay (CH50).

Results: Among the parameters investigated, PCA showed the greatest difference between the values representing active and inactive stages of the disease (p < 0.001), the highest correlation with SLEDAI (p < 0.001) and the highest sensitivity and specificity values (0.91, 0.88, respectively). Moreover, this value of PCA was the most useful in discriminating between active and inactive sample pairs.

Conclusion: We conclude that PCA is more useful in evaluating SLE activity than the single parameters studied.