Background Neutrophil-lymphocyte ratio (NLR) integrates the deleterious effects of neutrophilia and lymphopenia, and has been used as diagnostic and prognostic biomarker in various diseases (1). NLR was recently proposed as an inflammatory biomarker in systemic lupus erythematosus (SLE) (2).
Objectives 1. To compare the neutrophil count (NEU), lymphocyte count (LYM) and NLR between lupus patients with active disease and those with inactive disease. 2. To determine the diagnostic accuracy of these markers for detecting disease activity. 3. To compare the diagnostic accuracy of these markers.
Methods A retrospective comparative study. We compared two groups of lupus patients according to disease activity status (determined by Mex-SLEDAI). Subjects were age- and gender-matched. Normal distribution of the data was tested by the Shapiro-Wilk test. Comparisons between groups were performed by using Mann-Whitney U test. Associations between the variables were explored using Spearman's rho. A ROC curve was generated to determine the cutoff value in the NLR (and other markers) with the highest level of accuracy in identifying patients with active disease. Sensitivity and specificity were also calculated. Unless indicated otherwise, all results are expressed as median (25, 75%). A p-value below 0.05 was considered significant.
Results We included a total of 72 patients in this study, of whom 36 were classified as having active disease (34 females, aged 18-64 years), and 36 patients as having inactive disease (35 females, aged 20-53 years). Age and gender distributions were similar in the two groups. NEU was not significantly different between groups. LYM was comparatively lower in the group with active disease (963 [601.25, 1447.5] vs. 1540 [1110, 2030]). NLR was significantly higher in patients with active disease (4.784 [2.768, 6.885] vs. 2.306 [1.709, 4.605]). There were no significant relationships between NLR and Mex-SLEDAI, erythrosedimentation rate, serum albumin, or hemoglobin. ROC curve analysis for NLR showed an area under the curve (AUC) of 0.724 (95% CI 0.605-0.824, p=0.0002) with an optimal cutoff value of 2.42. Sensitivity and specificity were 82% and 55%, respectively. The AUC for predicting disease activity was 0.705 (95% CI 0.585-0.808, p=0.0012) for LYM. At a cutoff level of 993 cells/microliter, sensitivity and specificity were 62% and 80%, respectively. The pairwise comparison among the ROC curves showed no statistical difference (Fig. 1).
Conclusions NLR is not superior to LYM alone in differentiating disease activity in SLE. Therefore, NLR is probably not useful in clinical practice.
Eur J Gastroenterol Hepatol. 2015 Jan;27(1):108.
Acta Med Indones. 2013 Jul;45(3):170-4.
Acknowledgements We would like to extend our gratitude to Drs. Jesús Alberto Cárdenas-de-la-Garza and Raymundo Vera-Pineda for their help.
Disclosure of Interest None declared