Patients with pre-operative depression are 3.5x more likely to stay in a hospital for a week following surgery (p = 0.007)Every unit of increase in high sensitivity CRP measured between postoperative day 1–3 increased the odds of an increased length of stay by 1% (p = 0.030)Elevations in the level of CRP measured between postoperative days 4–8 significantly contributed to depression status and longer hospital stay (t = 2.62, p = 0.010). This evidence concerns the gene CRP and major depressive disorder.