Background/Purpose: Subjects with Systemic Lupus Erythematosus (SLE) are at elevated risk for end-organ damage. Lupus nephritis continues to be the complication with the highest standardized mortality ratio in SLE, yet clinicians have few tools to identify patients at risk. A complete blood count is a readily available test but little is known about its usefulness in tracking lupus nephritis and activity. In recent years, neutrophil/lymphocyte (NLR), monocyte/lymphocyte (MLR), and platelet/lymphocyte (PLR) ratios have emerged as markers of systemic inflammation. This study sought to evaluate the association between NLR, MLR, and PLR and its individual components and lupus disease activity and lupus nephritis.

Methods: 25 matched healthy controls and 85 patients fulfilling ACR or SLICC criteria for SLE were enrolled in the study and demographics, disease activity, as measured by the Hybrid SLEDAI, medications, and clinical manifestations were recorded. 20 lupus patients included in the study had active lupus nephritis, as defined by proteinuria greater than 500 mg/g creatinine. A complete blood cell count was assessed on all patients and healthy controls. Patients with platelet counts less than 100K or on nonsteroidal anti-inflammatory drugs were excluded from the study.

Results: Overall, SLE patients had a significantly higher PLR (p=0.0001), NLR (p=0.0003), and MLR (p=0.0035) compared to healthy controls. Lymphocyte counts alone negatively associated with SLEDAI (beta=-0.31, p=0.006) but monocyte, neutrophil, or platelet counts did not show a significant association with SLEDAI. All three ratios showed a significant positive association with SLEDAI in linear regression analysis with PLR being a better predictor than lymphocyte counts alone (beta=0.38, p< 0.0001). The associations between PLR or MLR but not NLR and SLEDAI remained significant in a multivariate linear regression model adjusting for age, race, sex, ethnicity, and medications. Specifically, the dose of glucocorticoids did not explain the clinical associations with these cellular ratios.  When evaluating active lupus nephritis, PLR (p=0.118) was not significant in a logistic regression and NLR (p=0.007) and MLR (p=0.007) performed equally well. These associations between NLR or MLR and active lupus nephritis persisted in a multivariate logistic regression model adjusting for age, race, sex, ethnicity, and medications. Interestingly, lymphocyte, monocyte, neutrophil, or platelet counts alone did not associate with active lupus nephritis.

Conclusion: These data suggest that by using standard clinical labs to calculate NLR, MLR, and PLR clinicians may be able to better characterize lupus activity and current lupus nephritis.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/association-between-neutrophil-to-lymphocyte-monocyte-to-lymphocyte-and-platelet-to-lymphocyte-ratios-and-lupus-disease-activity-and-lupus-nephritis/