Table 3.

Diagnostic value of the classic diagnostic parameters and detectable u-IL-16 for PLN

Parameters	Sensitivity	Specificity	PPV	NPV	P value*
PLN vs other active SLE
Positive a-dsDNA, %	81.8	39.0	43.4	79.0	0.025
Low C3, %	78.4	71.3	55.8	87.7	<0.0001
Low C4, %	91.9	55.0	48.6	93.6	<0.0001
u-IL-16†, %	67.0	91.0	77.5	85.1	<0.0001
PLN vs other LN classes
Positive a-dsDNA, %	81.8	51.4	66.0	63.3	0.012
Low C3, %	78.4	60.0	77.8	60.0	0.0082
Low C4, %	91.9	55.0	78.6	78.6	0.0002
u-IL-16†, %	67.0	83.8	83.3	66.0	<0.0001

*P value for two-tailed Fisher’s exact test.

†The most optimal threshold value to calculate u-IL-16 sensitivity and specificity for PLN was determined as 15.8 pg/mL or higher, based on receiver operator characteristic curve analysis. Information on missing data is provided in the legend of tables 1 and 2.

a-dsDNA, anti-double-stranded DNA; LN, lupus nephritis; NPV, negative predictive value; PLN, proliferative lupus nephritis; PPV, positive predictive value; SLE, systemic lupus erythematosus; u-IL-16, urinary interleukin 16.