The ratio of superoxide dismutase to standard deviation of erythrocyte distribution width as a predictor of systemic lupus erythematosus

Abstract

Background: To explore the clinical value of the serum superoxide dismutase-to-standard deviation of erythrocyte distribution width ratio (SRSR) in systemic lupus erythematosus (SLE).

Methods: A total of 222 SLE patients from the Rheumatology and Immunology Department in the Second Affiliated Hospital of Chongqing Medical University from January 2017 to April 2019 were collected as the experimental group, and a total of 202 healthy physical examiners were extracted as the control group. Neutrophil-to-lymphocyte ratio (NLR), superoxide dismutase-to-standard deviation of erythrocyte distribution width ratio (SRSR), and platelet-to-lymphocyte ratio (PLR) were calculated from the collected data and then compared the level of the above three indexes between the two groups. In addition, we analyzed the association between SRSR and clinically relevant indicators.

Results: We found that the SRSR of SLE patients was significantly lower than healthy control group, by analyzing the receiver operating characteristic (ROC) curve; it revealed that the SRSR had higher specificity and sensitivity than either superoxide dismutase (SOD) or standard deviation of erythrocyte distribution width (RDW-SD) alone. The area under the curve (AUC) for SRSR was significantly larger than either SOD or RDW-SD alone, and the AUC for SRSR was also larger than NLR and PLR. And it was found that SRSR was independently correlated with SLE disease activity through multiple linear regression analysis.

Conclusion: SRSR is a useful biomarker for the diagnosis of SLE, and it is of great significance in the clinical application.

Keywords: predictor; ratio; standard deviation of erythrocyte distribution width; superoxide dismutase; systemic lupus erythematosus.

Figure 1

Comparison of SRSR, NLR, and PLR between SLE and control groups by scatter plot, ^*** P < .05. A, shows the difference of SRSR in the two groups; B, shows the difference of NLR in the two groups; C, shows the difference of PLR in the two groups. NLR, neutrophil‐to‐lymphocyte ratio; PLR, platelet‐to‐lymphocyte ratio; SRSR, superoxide dismutase‐to‐standard deviation of erythrocyte distribution width ratio.

Figure 2

Correlation analysis and fitting curve. A, shows the correlation and curve between SRSR and ESR; B, shows the correlation and curve between SRSR and CRP; C, shows the correlation and curve between SRSR and anti‐dsDNA; D, shows the correlation and curve between SRSR and C3; E, shows the correlation and curve between SRSR and C4; F, shows the correlation and curve between SRSR and SLEDAI; G, shows the correlation and curve between NLR and ESR; H, shows the correlation and curve between NLR and CRP; I, shows the correlation and curve between NLR and anti‐dsDNA; J, shows the correlation and curve between NLR and C3; K, shows the correlation and curve between NLR and C4; L, shows the correlation and curve between NLR and SLEDAI; M, shows the correlation and curve between PLR and ESR; N, shows the correlation and curve between PLR and CRP; O, shows the correlation and curve between PLR and anti‐dsDNA; P, shows the correlation and curve between PLR and C3; Q, shows the correlation and curve between PLR and C4; R, shows the correlation and curve between PLR and SLEDAI; SRSR, superoxide dismutase‐to‐standard deviation of erythrocyte distribution width ratio; NLR, neutrophil‐to‐lymphocyte ratio; PLR: platelet‐to‐lymphocyte ratio. SLEDAI, SLE Disease Activity Index; C3, complement 3; C4, complement 4; ESR, erythrocyte sedimentation rate; CRP, C‐reactive protein; anti‐dsDNA, anti–double‐stranded DNA antibodies

Figure 3

Receiver operating characteristic curve of indicators in SLE patients. A, shows the ROC curve of SRSR; B, shows the ROC curve of NLR; C, shows the ROC curve of PLR; D, shows the ROC curve of SOD; E, shows the ROC curve of RDW‐SD; F, shows the ROC curve of WBC; G, shows the ROC curve of PLT; H, shows the ROC curve of C3; I, shows the ROC curve of C4; J, shows the ROC curve of anti‐dsDNA. C3, complement 3; C4, complement 4; NLR, neutrophil‐to‐lymphocyte ratio; PLR, platelet‐to‐lymphocyte ratio; PLT, platelet; RDW‐SD, standard deviation of erythrocyte distribution width; SOD, superoxide dismutase; SRSR, superoxide dismutase‐to‐standard deviation of erythrocyte distribution width ratio; WBC, white blood cell count.