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.