Boersema et al. in 2018 found that in 47 patients after colorectal surgery, the serum IL-6 ratio (preoperative/POD) cannot predict postoperative ileus but can predict infectious complications on POD1 and POD 3 with a larger AUC than CRP (0.825 and 0.801 vs. 0.732 and 0.731) [36]. Here, CRP is linked to ileus.