Baseline neutrophil-to-lymphocyte ratio combined with SLEDAI predicts lupus low disease activity state at 1 year: a cohort study.

BACKGROUND

Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease in which treat-to-target management increasingly emphasizes attainment of Lupus Low Disease Activity State (LLDAS). Complete blood count (CBC)-derived inflammatory indices are inexpensive and readily available markers, but their value for predicting subsequent LLDAS remains unclear.

METHODS

This retrospective cohort study included 165 hospitalized patients with SLE at Peking University International Hospital between 2022 and 2024 who had baseline CBC data and completed 1-year follow-up. Baseline neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), systemic immune-inflammation index (SII), and systemic inflammation response index (SIRI) were calculated from routine hematologic parameters. The primary outcome was LLDAS achievement at 1 year according to Asia Pacific Lupus Collaboration criteria. Univariable and multivariable logistic regression analyses were performed. Multivariable models adjusted for baseline SLEDAI-2K, age, sex, immunosuppressant use, and prednisone dose. Receiver operating characteristic (ROC) analysis, bootstrap internal validation, calibration, and decision curve analysis (DCA) were also conducted.

RESULTS

Compared with non-LLDAS patients, those who achieved LLDAS had lower baseline SLEDAI-2K, lower prevalence of renal involvement, lower neutrophil counts, higher hemoglobin levels, and lower baseline NLR, PLR, SII, and SIRI. In univariable analysis, higher baseline NLR (OR 0.69, 95% CI 0.57-0.83, P < 0.001), PLR (OR 0.96 per 10-unit increase, 95% CI 0.93-0.99, P = 0.008), and SII (OR 0.86 per 100-unit increase, 95% CI 0.79-0.94, P < 0.001) were associated with lower odds of LLDAS. In the adjusted model, baseline NLR remained independently associated with LLDAS attainment (aOR 0.690, 95% CI 0.561-0.848, P < 0.001). The NLR+SLEDAI-2K model achieved an AUC of 0.746, with limited optimism on bootstrap validation.

CONCLUSION

Baseline CBC-derived inflammatory indices, particularly NLR, were associated with 1-year LLDAS attainment in SLE. NLR, combined with SLEDAI-2K, may provide a practical, low-cost adjunct for early risk stratification in treat-to-target-oriented SLE management.