Statistical analyses were performed using SPSS 17.0 (SPSS Inc.; Chicago, Illinois USA) and GraphPad Prism 5.0 (GraphPad Software Inc.; La Jolla, California USA) from an anonymous database. Normally distributed continuous variables (Kolmogorov–Smirnov test) were expressed as mean ± SD unless otherwise indicated. Differences between continuous variables were analysed using unpaired t-test with Welch's correction. Differences between two nominal variables were analysed using the chi-square test. ANOVA was used to analyse differences between more than two groups. Associations between variables were assessed by Pearson and Spearman correlation coefficients, respectively. Variables, which significantly correlated with plasma fibrinogen concentrations were further analysed in an univariate linear regression model at first. Multivariate linear regression analysis with forced entry selection of the covariates age, sex and WHO FC was constructed afterwards. Two-sided values of p < 0.05 were considered statistically significant.