Assessment of anti-desmoglein antibodies levels and other laboratory indexes as objective comprehensive indicators of patients with pemphigus vulgaris of different severity: a single-center retrospective study

The aim of this study is to assess the utility of anti-desmoglein (Dsg) antibodies levels, hematological biomarkers levels, the albumin to globulin (A/G) ratio, blood lipids levels, and lymphocyte subpopulation percentages as objective laboratory indicators of disease severity of pemphigus vulgaris (PV). A retrospective study of 187 PV patients with 256 medical records between January 2013 and December 2020. PV patients were divided into three groups by disease severity according to the pemphigus disease area index (PDAI) score: mild (0–8), moderate (9–24), and severe (≥ 25). The levels of anti-Dsg antibodies, hematological biomarkers, A/G ratio, blood lipids, and the percentage of lymphocyte subpopulations were measured. We assessed the correlations of quantitative variables by Pearson correlation (r). Multivariable linear regression was used to identify the variables associated with the disease severity of PV (PDAI score). The results show that the levels of Dsg1 (r = 0.294, P < 0.001) and Dsg3 (r = 0.206, P = 0.011), monocyte count (r = 0.210, P = 0.001), neutrophil-to-lymphocyte ratio (NLR) (r = 0.123, P = 0.049), and platelet-to-lymphocyte ratio (PLR) (r = 0.170, P = 0.006) were positively correlated with the PDAI score. However, the A/G ratio (r = − 0.399, P < 0.001), and the levels of total serum cholesterol (r = − 0.140, P = 0.026) and HDL (r = − 0.143, P = 0.023) were negatively correlated with the PDAI score. Multiple linear regression showed that the factors associated with the PDAI score were higher level of anti-Dsg1 antibody (P = 0.001), a higher NLR (P = 0.005), and a lower A/G ratio (P < 0.001). The linear regression equation was Y_(PDAI) = 32.798 + 0.058X_(Dsg1) + 0.846 X_(NLR)−16.472 X_(A/G) (R² = 0.586). Therefore, high levels of anti-Dsg1 antibody and NLR combined with a low A/G ratio could explain the PDAI score. These findings might provide a more comprehensive and objective evaluation system for reflecting the disease severity of PV based on laboratory indicators.