73.1% of patients with pre-operative depression had a length of stay over 7 days. In comparison, 56.5% of patients without preoperative depression had a length of stay over 7 days.Following stratification of preoperative BDI scores into depressed or non-depressed (BDI < 10), there was no association between binary BDI scores and length of postoperative hospital stay.Post-operative CRP measured at postoperative day 4–6 was associated with a prolonged hospital stay (OR: 1.017, 95% CI: 1.005–1.029, p = 0.009).No association detected between pre-operative BDI scores and CRP levels. This evidence concerns the gene CRP and major depressive disorder.