The Significance of Newly Derived Disease Activity Parameters Neutrophil/Albumin Ratio, Neutrophil/Complement C3 Ratio, and Albumin/Globulin Ratio in a Group of Patients With Lupus Nephritis

Introduction: Lupus nephritis (LN) is the most serious manifestation of systemic lupus erythematosus (SLE), which worsens the course and prognosis of this autoimmune disease. The standard assays we use to assess LN activity still do not have sufficient sensitivity. The aim of this study was to determine the parameters neutrophil/albumin ratio (NAR), neutrophil/complement C3 ratio (NC3r), and albumin/globulin ratio (AGR) in patients with LN, as well as the significance of these parameters in comparison with the standard parameters that we use to determine the activity of lupus nephritis. Methods: Of the total number of subjects (72 patients) with lupus nephritis (mean age: 43.62 ± 14.38 years), who were included in this study, 50% (36) of the patients had active disease (group A-LN), and the other half had disease in remission (group R-LN). In addition to standard laboratory parameters, we also determined the derived parameters NAR, NC3r, and AGR. Results: In the group comparison, a significant difference was observed in the following parameters: albumin, complement C3, antinuclear antibody (ANA), anti-double-stranded DNA antibody (anti-ds-DNA Ab), proteinuria g/24h (proteins from 24 hours collected urine), and Systemic Lupus Erythematosus Activity Index/renal (SLEDAI/r) (p < 0.000). Correlation of NAR with total proteins (r = -0.359, p = 0.003), albumin (r = -0.590, p < 0.001), SLEDAI/r (r = 0.460, p < 0.001), and proteinuria g/24h (r = 0.515, p < 0.001) was significant in the A-LN group. Correlation of NC3r with total proteins (r = -0.340, p = 0.003), albumin (r = -0.584, p < 0.001), C3 (r = -0.474, p < 0.001), anti-ds-DNA Ab (r = 0.283, p = 0.019), proteinuria g/24h (r = 0.586, p < 0.001), and SLEDAI/r (r = 0.559, p < 0.001) was significant in the A-LN group. AGR in the A-LN group significantly correlated with albumin (r = 0.581, p < 0.001), C3 (r = 0.376, p = 0.023), and SLEDAI/r score (r = -0.354, p = 0.036). According to the coordinates on the receiver operating characteristic (ROC) curve for NAR, the cutoff value is 0.104, the sensitivity is 72.2%, and the specificity is 66.7%; for parameter NC3r, the cutoff value is 4.849, the sensitivity is 83.3%, and the specificity is 69.4%; and for AGR, the cutoff value is -1.608, the sensitivity is 30.6%, and the specificity is 63.9%. Conclusion: Our data show a significant relationship between NAR, NC3r, and AGR and lupus activity. NC3r has proven to be the most significant in providing valuable data for identifying patients with active LN and as a simple indicator in clinical practice.