Changes of Platelet Indices in Patients with Systemic Lupus Eythematosus and their Correlation with Disease Activity

Background: Systemic lupus erythematosus (SLE) is autoimmune disease needs continuous assessment of disease activity. There is no single biomarker used for that purpose. Platelet indices have recently been found to be a simple inflammatory marker used in the assessment of systemic inflammation in many diseases like, rheumatoid arthritis, ankylosing spondylitis and inflammatory bowel diseases.Aim of Study: To evaluate platelet indices [mean platelet volume (MPV), platelet distribution width (PDW) and platelet-crit (PCT)] as markers of disease activity in patients with SLE.Patients and Methods: In this cross sectional study we tested 100 subjects; 20 healthy control and 80 SLE patients recruited from rheumatology unit in Internal Medicine De-partment, Tanta University, Tanta, Egypt. Then the lupus patients were divided according to SLEDAI into 20 patients without flare (SELEDAI <4), 17 patients mild flare (SELEDAI 4– <8), 25 patients moderate flare (SELEDAI 8 – <12) and 18 patients severe flare (SELEDAI >_12). Platelet indices (MPV, PDW, PTC) were assessed in all of them and their correlation to SLEDAI score were analyzed.Results: MPV and PDW had no clinical significance in assessing lupus activity, PCT significantly lower with SLE patients with severe flare and it had a significant negative correlation with SELEDAI score with cutoff value equals <_0.173, sensitivity 61.11%, specificity 79.03%, PPV 45.8% and NPV 87.5%. Finally there was no significant difference between lupus nephritis and lupus without nephritis patients in Platelet indices.Conclusion: Plateletcrit (PCT) can be used as a new marker for SLE activity.