Association of red blood cell distribution width with plasma lipids in a general population of unselected outpatients.

Background and aim: Increased values of red blood cell distribution width (RDW) are frequent in patients suffering from cardiovascular disorders, and are associated with traditional or less conventional risk factors. Nevertheless, limited and controversial information exists on the association between anisocytosis and plasma lipids. Methods: We performed a retrospective search to retrieve test results of RDW and plasma lipids of unselected outpatients aged 18 years or older referred for routine testing over a six-month period. No restrictive inclusion or exclusion criteria were applied for extracting data of total cholesterol, low density lipoprotein (LDL)-cholesterol, high density lipoprotein (HDL)-cholesterol, total to HDL-cholesterol ratio (COL/HDL) and atherogenic index of plasma (AIP). Cumulative results were retrieved for 4,874 outpatients (2,150 men, 2,724 women). Results: A significantly higher median RDW was found in females than in males (13.2 vs. 13.1; p < 0.01). After stratification of the study population into RDW quartiles, significant differences were observed in all parameters, except triglycerides and COL/HDL in men. RDW was negatively correlated with haemoglobin and mean corpuscular volume (MCV), and positively associated with age. After comparison of lipid values across RDW quartiles by multivariate logistic regression adjusted for age, haemoglobin and MCV, the RDW was negatively associated with HDL-cholesterol (OR 3.20 in females and OR 1.67 in males), and positively associated with AIP (1.53 in females and 1.43 in males), hypertriglyceridaemia (OR 1.66) and COL/HDL (OR 1.28) in women. Conclusions: Higher RDW is associated with a globally unfavourable lipid profile, especially in women.