Platelet parameters, neutrophil–lymphocyte ratio, platelet lymphocyte ratio, red cell distribution width: can they serve as biomarkers in evaluation of severity of psoriasis?

BACKGROUND: Psoriasis has a multifactorial pathogenesis encompassing genetic, environmental, and immunological factors. There is a dire need for specific, cost effective, reliable, and universally accepted laboratory marker as indicator of severity of psoriasis. MATERIALS AND METHODS: A cross-sectional study was conducted on 50 psoriasis patients and 50 healthy controls. Hematological parameters including platelet indices (platelet count [PC], plateletcrit, mean platelet volume [MPV], platelet large cell ratio, platelet distribution width [PDW]), neutrophil–lymphocyte ratio (NLR), platelet–lymphocyte ratio (PLR), and red blood cell distribution width (RDW) were evaluated and correlation of these indices among themselves and with Psoriasis Area and Severity Index (PASI) analyzed. Statistical analyses were performed using SPSS version 19.0 (SPSS Inc., Chicago, IL, USA). RESULTS: A statistically significant difference in RDW, PC, MPV, PDW, NLR, and PLR was observed between psoriasis versus controls and mild versus moderate to severe psoriasis. There was a significant positive correlation between PASI and RDW, MPV, platelets, PLR while erythrocyte sedimentation rate showed a significant correlation with MPV. MPV and RDW, RDW and NLR, and RDW and PLR were also found to be correlated. MPV showed highest sensitivity and specificity both. MPV (area under the curve: 0.970, P < 0.001) demonstrated better predictive power as per area under curve of receiver-operator curve as compared to other parameters for psoriasis. CONCLUSION: The present study assessed the role of simple and low-cost parameters easily computed from routine tests like complete blood count as biomarkers for severity of psoriasis. Mean values of MPV, RDW, NLR, and PLR were found to be higher in psoriasis patients compared to controls. Moreover, a significant correlation was observed between PASI and these novel markers. However, additional large-scale, multicenter studies need to be conducted before application of these parameters in clinical practice.