PMCH and Behcet disease: Significant ratio changes for 8 pairs of variables were ultimately validated in the discovery set (Table S5), among which TP/MCV, PCT/MONO, TP/MCH, and TP/MCHC were found to be significantly increased in BD compared with HC, AAV and TA in the discovery and validation sets (P < 0.05, Fig. 6, Table 3; Table S5), regardless of immunomodulatory therapy (P > 0.05, Table 3; Table S5).