Complement component 3 (C3) index (quotient of complement component 3 (Q C3)/quotient of alpha2 macroglobulin (Q α2MG)).

<p>(A) Comparison of C3 index between NPSLE and non-NPSLE. (B) Comparison of C3 index among the subsets of NPSLE. ACS, acute confusional state; non-ACS, diffuse NPSLE other than ACS; Focal, focal NPSLE. Data are shown as box plots. The boxes indicate the upper and lower interquartile range (IQR), the lines within the boxes indicate the median, the whiskers indicate the minimum and maximum IQR. Each dot represents an individual sample. Statistical analysis was performed using the Mann-Whitney <i>U</i>-test.