 Statistical analysis Descriptive statistics were presented with frequency and percent for categorical data, and with mean and standard deviation for numerical data. Comparisons between 2 independent groups were conducted with Mann-Whitney U test, and Chi-Square test for non-normally distributed numerical, and categorical variables, respectively. Pairwise Pearson correlation was executed to estimate linear relationship between characteristics. Receiver operating characteristic ROC curve analysis was utilized to determine the optimum cutoff level of the association of RDW with MPA. All statistical calculations were performed using SAS version 9.3 SAS, 2014. The results were considered statistically significant when the p value was 0.05. 