In this secondary analysis of consecutive ED patients with CAP from a large multicentre antibiotic stewardship trial , we used adjusted multivariate regression models to determine the magnitude and statistical significance of differences in mean baseline concentrations of five biomarkers ( procalcitonin -LSB- PCT -RSB- , C-reactive protein -LSB- CRP -RSB- , white blood cells count -LSB- WBC -RSB- , proadrenomedullin -LSB- ProADM -RSB- , copeptin ) associated with six pre-analytic factors ( antibiotic or corticosteroid pretreatment , age , gender , chronic renal failure or chronic liver insufficiency ) .