Clinical Usefulness of Hematologic Indices as Predictive Parameters for Systemic Lupus Erythematosus

Amirhossein Peirovy, MD; Aida Malek Mahdavi, PhD; Alireza Khabbazi, MD; Mehrzad Hajialilo, MD; Ebrahim Sakhinia, PhD; Nadereh Rashtchizadeh, PhD


Lab Med. 2020;51(5):519-528. 

In This Article

Abstract and Introduction


Objective: This study assessed the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), mean platelet volume, platelet distribution width, and red cell distribution width (RDW) in systemic lupus erythematosus (SLE) patients and their correlation with disease activity.

Methods: Two hundred eight SLE patients and 205 age- and sex-matched healthy controls were included. Disease activity was assessed using the systemic lupus erythematosus disease activity index 2000, and hematological indices were determined.

Results: Lymphocyte and platelet counts were significantly lower in SLE patients than in the controls, while the NLR, PLR, and RDW were significantly higher (P < .05). In patients with active disease, the neutrophil counts, NLR, and PLR were significantly higher than in those with inactive disease (P < .05), while the lymphocyte count was significantly lower (P < .05). Based on receiver operating characteristic curve analyses, only for lymphocyte count and PLR. The area under curve was significantly higher (P = .001 and P = .053, respectively).

Conclusion: PLR can serve as a biomarker for indicating SLE disease activity.


Systemic lupus erythematosus (SLE) is a chronic inflammatory disease with periods of exacerbation and remission that is characterized by an autoantibody formation against nuclear and cytoplasmic antigens.[1] Measurement of disease activity in SLE has a central role in clinical research and daily clinical practice for evaluating the response to treatment and clinical outcomes. The main challenges in measuring SLE disease activity are the multisystem nature of disease and the variation in disease activity involving 1 or multiple organs, which may vary between patients and even in the same patient over time.[1] Since no single measure can describe the condition in all SLE patients, complex and standardized measures composed of clinical and laboratory variables have been developed to evaluate SLE disease activity.[1] These measures use laboratory parameters like serum complement protein concentrations, complete blood count (CBC), and anti–double-stranded deoxyribonucleic acid (anti-dsDNA) antibody levels. However, there is still no reliable laboratory test that can independently measure SLE disease activity. Therefore, identifying novel biomarkers capable of monitoring the activity of SLE disease and improving the accuracy of currently available disease activity assessment tools are essential.

The CBC test is a common examination in the diagnosis and follow-up of rheumatic diseases. White blood cell count and its subtypes, like neutrophil and lymphocyte counts, have been identified as biomarkers of inflammation in several diseases. Recently, hematological indices, including the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), mean platelet volume (MPV), platelet distribution width (PDW), and red cell distribution width (RDW), have been proposed as prognostic markers to determine the systemic inflammatory response and have been used in combination with other inflammatory markers to determine inflammation in several diseases, including autoimmune disorders.[2–4] Hematological indices are calculated from the CBC and can be considered inexpensive and easily attainable markers of inflammation.[4]

NLR is a parameter for assessing the inflammatory status of a subject in inflammatory disorders like rheumatoid arthritis (RA) and ulcerative colitis,[5,6] major cardiac events[7] and cancers.[8] NLR tends to increase in inflammatory disorders due to an increased number of neutrophils and decreased number of lymphocytes. Platelets, by releasing proinflammatory mediators such as chemokines and cytokines, play an important role in inflammatory reactions and immune responses.[9] Previous research demonstrated that higher platelet and lower lymphocyte counts were associated with adverse clinicopathological manifestations in some cancers[10] and myocardial infarction.[11] There are few studies that demonstrate an association between PLR and disease activity in autoimmune diseases like RA[12] and SLE.[2,13] MPV, an accurate measure of platelet size, is one of the most commonly used biomarkers of platelet function and activation.[14] MPV has been studied as a simple inflammatory marker in numerous chronic diseases, and a correlation has been demonstrated between the MPV and active inflammatory disorders.[15,16] A previous study showed that MPV was correlated with disease activity in active inflammatory bowel disease.[17] Moreover, MPV was evaluated in chronic inflammatory diseases such as RA, ankylosing spondylitis (AS), and Behcet's disease,[18–20] and it was found to be correlated with inflammatory process, disease activity, and response to treatment in RA and AS.[21,22] PDW is another marker of platelet activation which represents the heterogeneity in platelet morphology. Kisacik et al.[22] reported lower PDW in AS and RA patients than in the controls. In addition, Işık et al.[23] demonstrated PDW to be a negative acute-phase reactant for RA. RDW is a measure of the range of variation of red blood cells. Lippi et al.[24] reported an association between systemic inflammation and RDW.

Despite studies performed on the values of NLR, PLR, MPV, PDW, and RDW in SLE patients, it is not clear which values of these parameters are correlated with a higher risk for SLE patients, which cutoff point for these hematological indices can separate normal from abnormal results, and if there is any association between hematological indices and specific organ involvement. The aim of the current study is to assess NLR, PLR, MPV, PDW, and RDW in patients with SLE, as well as their correlation with the activity of disease.