Mean Platelet Volume (MPV) as an indicator of  disease activity and severity in lupus

Background: Amongst the different clinical and laboratory parameters used to monitor disease activity in systemic lupus erythematosus (SLE), mean platelet volume (MPV) is a novel biomarker. Although MPV has been studied in other rheumatological conditions like rheumatoid arthritis, its role in adult SLE needs to be defined, especially in Pakistan. Methods: The aim of this study was to evaluate the role of MPV as a biomarker of disease activity in SLE. Fifty patients were recruited through a consecutive non-probability sampling technique for this cross-sectional study. On the basis of their SLE disease activity index (SLEDAI) score of greater or lesser than 5, these 50 participants were divided into two equal groups respectively;25 patients with active SLE, and another 25 participants with stable, inactive lupus. MPV was measured in each group and compared using SPSS version 16. MPV was also correlated with SLEDAI and erythrocyte sedimentation rate (ESR). Independent sample t-test and Spearman’s rho and Pearson’s correlation tests were applied. Sensitivity and specificity of MPV were checked through ROC analysis. Results: The MPV of patients with active SLE (n=25, mean [M]=7.12, SD=1.01) was numerically lower than those in the inactive-SLE group (n=25, M= 10.12, SD=0.97), and this was statistically significant ( P<0.001). MPV had an inverse relationship with both ESR (r=-0.93, P<0.001) and SLEDAI (r (s)= -0.89, P<0.001). However, there was a strong positive correlation between ESR and SLEDAI (r (s)=0.90, P<0.001). For MPV, a cutoff value of less than 8.5fl had a sensitivity of 92% and a specificity of 100% ( P< 0.001). Conclusions: Higher disease activity in SLE is associated with a correspondingly low MPV.