Neutrophil-to-C3 ratio and neutrophil-to-lymphocyte ratio were associated with disease activity in patients with systemic lupus erythematosus

Background Systemic lupus erythematosus is prone to recurrent attacks, and its treatment is related to disease activities. It is important to accurately assess the patient's disease activity. So, the purpose of this study was to investigate the relation between neutrophil-to-C-3 ratio (NC3R), neutrophil-to-lymphocyte ratio (NLR), and disease activity in patients with Systemic lupus erythematosus (SLE). Methods This was a retrospective study. One hundred and ninety-four patients with SLE and 71 healthy controls were included in this study. We divided the patients into two groups according to the SLE disease activity (SLEDAI). Group 1 included patients with a score of >9 (patients with severe disease activity), and Group 2 included patients with a score of 9 and lower (patients with mild disease activity). Correlations between NC3R, NLR, and disease activity were analyzed. Results NC3R and NLR in patients with SLE were obviously higher compared to healthy controls (P < 0.05). There was an obviously significant difference in NC3R and NLR between Group 1 and Group 2 (P < 0.05). SLEDAI scores were positively correlated with NC3R (r = 0.353, P < 0.01) and NLR (r = 0.237, P = 0.01). Receiver operating characteristic (ROC) curve analysis showed that the cutoff value of NC3R to identify SLE with high disease activity was 5.935, with sensitivity and specificity being 75.9% and 67.0%, while that of NLR was 2.293, with sensitivity being 68.9% and specificity being 82.8%. Conclusion NC3R and NLR are two useful inflammatory markers for evaluating disease activity in patients with SLE.