Perioperative inflammatory response and protein S-100β concentrations - relationship with post-operative cognitive dysfunction in elderly patients

Background: One major concern in about one third of elder patients after total hip-replacement surgery is post-operative cognitive dysfunction (POCD). Previous studies have suggested that cognitive impairment is accompanied with changes in serum S-100 beta protein (S-100 beta) and inflammatory markers. Thus, the aim of the current study was to investigate the value of serum S-100 beta and interleukin(IL)-1 beta, IL-6, tumour necrosis factor-alpha (TNF-alpha), and C-reactive protein (CRP) in reflecting POCD after total hip-replacement surgery. Methods: Forty-two elderly patients were enrolled, and 37 patients completed the follow-up. Serum S-100 beta protein and IL-1 beta, IL-6, TNF-alpha, and CRP were determined pre-operatively, as well as 1 h and 6 h post-operatively. Neuropsychological tests were performed pre-operatively, as well as on day 1, 3, and 7 post-operatively. Results: Seventeen (45.9%, 17/37) patients developed POCD 1 day after surgery, and three (8.1%, 3/37) developed POCD 7 days after surgery. [Correction added after publication 7 February 2012: in the preceding sentence (54.1%, 17/37) was corrected to (45.9%, 17/37)]. Patients with POCD 1 day after surgery had significantly higher serum levels of IL-6 at 6 h (135 +/- 32 pg/ml vs. 91 +/- 29 pg/ml, P < 0.05) and S-100b at 1 h (1872 +/- 385 pg/ml vs. 1289 +/- 143 pg/ml, P < 0.05. No significant post-operative change was detected in levels of TNF-alpha, IL-1, or CRP. Conclusion: The serum levels of pro-inflammatory marker IL-6 and S-100 beta protein increased after total hip-replacement in elderly patients, and such increase may serve as predicting parameters for the occurrence of POCD.