The neutrophil-to-lymphocyte ratio as a surrogate marker for disease activity in systemic lupus erythematosus: a correlation study using the SLE-DAS.

BACKGROUND

The neutrophil-to-lymphocyte ratio (NLR) is a potential surrogate marker for disease activity in many rheumatic diseases.

OBJECTIVE

To study the correlation between NLR and disease activity of systemic lupus erythematosus (SLE) using the SLE disease activity score (SLE-DAS).

DESIGN

Retrospective, cross-sectional.

METHODS

Consecutive adult patients who fulfilled the American College of Rheumatology (ACR) or Systemic Lupus International Collaboration Clinic (SLICC) criteria for SLE were recruited between March 2023 and February 2024. SLE activity was assessed by physicians' global assessment (PGA), SLE-DAS, and SLE disease activity index-2000 (SLEDAI-2K). The calculated NLR was correlated with disease activity indices and serological parameters (anti-dsDNA, C3/4) by Spearman's rank correlation. Patients were stratified into SLE-DAS remission, mild, and moderate/severe disease activity, and a comparison of the NLR was performed among these subgroups by one-way ANOVA.

RESULTS

A total of 420 SLE patients were studied (93.1% women, age 31.6 ± 13.1 years, SLE duration 15.7 ± 8.1 years). Moderate/severe, mild disease activity and SLE-DAS remission were present in 70 (16.7%), 65 (15.5%), and 285 (67.9%) patients, respectively. SLE-DAS correlated significantly with SLEDAI-2K (rho 0.90; p < 0.001) and PGA (rho 0.60; p < 0.001). The mean NLR of all patients was 3.54 ± 4.0 and NLR correlated significantly with SLE-DAS (rho 0.17; p < 0.001). The NLR was significantly higher in patients with active disease in the SLE-DAS renal domain than those in remission (5.17 ± 7.11 vs 3.22 ± 3.19; p = 0.03). The NLR in patients with moderate/severe SLE-DAS activity (5.25 ± 6.89) was significantly higher than those with mild activity (3.12 ± 2.26; p < 0.01) or remission (3.22 ± 3.19; p < 0.01). ROC analysis showed that an NLR cut-off of 3.11 showed a sensitivity of 55.6% and specificity of 68.7% in detecting moderate/severe SLE-DAS activity (area under the curve 0.67 (0.6-0.7); p < 0.001).

CONCLUSION

The NLR is a convenient marker that correlates significantly with disease activity in SLE.