Red Blood Cell Distribution Width is a Reliable Marker of Inflammation in Plaque Psoriasis

Psoriasis is a systemic inflammatory disease accepted as an independent risk factor for cardiovascular diseases (CVD). Elevated levels and correlation of red cell distribution width (RDW) with inflammatory markers has recently been shown in studies investigating CVD risk and prognosis in rheumatoid arthritis and ankylosing spondylitis. The aim of this study was to evaluate levels and correlation of RDW with inflammatory markers in patients with plaque psoriasis. Data including demographics, disease severity indices, laboratory parameters, and bioelectrical impedance analysis was collected from medical charts of patients who were diagnosed with plaque psoriasis at the Hacettepe University Department of Dermatology between March 2014 and August 2015. Patients were evaluated for major CVD risk factors defined by international guidelines. 199 patients with psoriasis and 73 volunteers were included. Patients had statistically significant higher values of metabolic age, visceral fat rating, body-mass index (BMI), red blood cells (RBC), white blood cells (WBC), red blood cell distribution width (RDW), alanine aminotransferase (ALT), uric acid, low-density lipoprotein (LDL), and C-reactive protein (CRP) (p=0.044, p=0.047,p=0.029, p= 0.005, p=0.02, p<0,01, p=0.001, p=0,016, p=0,014, p<0.01). A statistically significant relationship and positive correlation between RDW and CRP levels was found in the patient group (p=0.01, r=0.396). Patients without major CVD risk factors (n=79) had significantly higher values of RDW, LDL, and CRP (p=0.01, p=0.031, p=0.03, respectively). Patients with psoriasis who had one or more CVD risk factors (n=120) had significantly higher values of BMI, RDW, thrombocytes, ALT, and CRP (p=0.038, p=0.01, p=0.017, p=0.02, p=0.01, respectively). RDW, which is elevated as well as CRP, reflects the systemic inflammatory burden and can be used for prediction of CVD in psoriasis. In fact, patients with psoriasis who do not have any major CVD risk factors still have high levels of CRP and RDW, supporting the hypothesis that psoriatic inflammation itself can simultaneously cause CRP and RDW elevation. Coexistence of CVD risk factors is associated with ALT elevation since additional CVD risk factors may predict psoriatic comorbidities such as non-alcoholic fatty liver disease.