Differential approach to peripheral blood cell ratios in patients with systemic lupus erythematosus and various manifestations

New markers of systemic lupus erythematosus (SLE) activity are under investigation. In recent years, the researchers have been focusing increased attention on the role of haematological indicators in assessing the disease activity. Specifically, neutrophil-, basophil-, eosinophil-, monocyte- and platelet-to-lymphocyte ratios (NLR, BLR, ELR, MLR and PLR) have been considered. The specific objective of this study was to determine the suitability of the haematological markers for the assessment of SLE activity and SLE-related organ damage. This study is a retrospective analysis of 136 patients with SLE (124 women and 12 men) who received chloroquine/hydroxychloroquine (HQ/HCQ) monotherapy or HQ/HCQ therapy combined with low/medium doses of glucocorticoid. All patients were assessed for disease activity using the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) scale. In addition, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) inflammatory parameters were determined in each patient. NLR, BLR, ELR, MLR and PLR were evaluated and correlated with the SLE activity parameters and inflammatory markers. The mean values of the haematological indicators were compared in particular manifestations of SLE-induced organ damage. For numerical variables, descriptive statistics were calculated: median, standard deviation, minimum and maximum values. The Mann–Whitney U test was used for the comparison of continuous variables in the two groups. The Spearman rank correlation test was used to search for any relationships between variables. A p value < 0.05 was considered to be statistically significant. We have found a positive correlation between ELR, MLR and the SLEDAI scale (r = 0.22 and r = 0.27, respectively). NLR, MLR and PLR ratios were significantly correlated with ESR and CRP. Considerably higher NLR values were found in patients with cutaneous and/or mucosal symptoms and with kidney involvement compared to patients without such involvement (4.26 ± 4.2 vs 3.27 ± 2.7; p = 0.05 and 5.45 ± 5.6 vs 3.05 ± 2.0; p < 0.001 respectively). BLR and MLR were significantly higher in patients manifesting symptoms of vasculitis (0.09 ± 0.1 vs 0.02 ± 0.01; p < 0.001 and 3.1 ± 4.2 vs 0.3 ± 0.1; p < 0.001 respectively), arthritis and/or myositis (0.04 ± 0.09 vs 0.02 ± 0.01; p = 0.01 and 1.02 ± 2.6 vs 0.35 ± 0.4; p = 0.01 respectively), whereas elevated ELR ratios were observed in patients with vasculitis (0.4 ± 0.5 vs 0.08 ± 0.06; p < 0.001) compared to patients without such organ involvement. The PLR marker was substantially higher in patients exhibiting haematological disorders in the course of SLE (276.6 ± 226.4 vs 192.6 ± 133.5; p = 0.01). The results indicate that ELR and MLR are effective markers of SLE activity. The haematological indicators may predict SLE-dependent organ damage, particularly cutaneous, mucosal, arthritic, myositic, haematological and kidney involvement.