Are laboratory tests useful for monitoring the activity of lupus nephritis? A 6-year prospective study in a cohort of 228 patients with lupus nephritis.
OBJECTIVE
To evaluate the role of immunological tests for monitoring lupus nephritis (LN) activity.


METHODS
C3, C4, anti-dsDNA and anti-C1q antibodies were prospectively performed over 6 years in 228 patients with LN.


RESULTS
In membranous LN only anti-C1q antibodies differentiated proteinuric flares from quiescent disease (p = 0.02). However, in this group 46% of flares occurred with a normal value of anti-C1q antibodies versus 20% in proliferative LN (p = 0.02). In patients with antiphospholipid antibodies (APL), 33% of flares occurred with normal levels of anti-C1q antibodies versus 14.5% in patients that were APL-negative (p = 0.02). In proliferative LN, anti-C1q antibodies showed a slightly better sensitivity and specificity (80.5 and 71% respectively) than other tests for the diagnosis of renal flares. All four tests had good negative predictive value (NPV). At univariate analysis anti-C1q was the best renal flare predictor (p<0.0005). At multivariate analysis, the association of anti-C1q with C3 and C4 provided the best performance (p<0.0005, p<0.005, p<0.005 respectively).


CONCLUSIONS
Anti-C1q is slightly better than the other tests to confirm the clinical activity of LN, particularly in patients with proliferative LN and in the absence of APL. All four "specific" tests had a good NPV, suggesting that, in the presence of normal values of each, active LN is unlikely.
Moroni
G
G
Division of Nephrology, Fondazione Ospedale Maggiore, Mangiagalli, Regina Elena, Milan, Italy. gmoroni@policlinico.mi.it
Radice
A
A
Giammarresi
G
G
Quaglini
S
S
Gallelli
B
B
Leoni
A
A
Li Vecchi
M
M
Vecchi
M L
ML
Messa
P
P
Sinico
R A
RA
D000328:Adult; D000974:Antibodies, Antinuclear / Q000097:blood; D001323:Autoantibodies / Q000097:blood; D015415:Biomarkers / Q000097:blood; D015922:Complement C1q / Q000276:immunology; D003176:Complement C3 / Q000378:metabolism; D003181:Complement C4 / Q000378:metabolism; D004247:DNA / Q000276:immunology; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D008181:Lupus Nephritis / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D055815:Young Adult
D000974:Antibodies, Antinuclear; D001323:Autoantibodies; D015415:Biomarkers; D003176:Complement C3; D003181:Complement C4; D015922:Complement C1q; D004247:DNA