Comparison of cortisol and inflammatory response between aged and middle-aged patients undergoing total hip arthroplasty: a prospective observational study

BACKGROUND To investigate the differences in the perioperative serum cortisol, C-reactive protein (CRP) and interleukin-6 (IL-6) levels between aged and middle-aged patients undergoing total hip arthroplasty (THA). METHODS Sixty patients (30 aged and 30 middle-aged) undergoing THA for osteoarthritis between August 2016 and January 2017 participated in this study. Blood samples were collected preoperatively and at 6 hours, 24 hours and 3 days after surgery to measure the cortisol, CRP and IL-6 concentrations. The clinical outcomes were assessed using the visual analogue scale (VAS) pain score and Harris hip score (HHS). RESULTS No significant differences were found between the two groups before the operation in the cortisol, IL-6 and CRP levels; the VAS score; or the HHS. Cortisol was significantly lower at 6 hours after surgery in the aged group than in the middle-aged group (P < 0.05). IL-6 at 6 and 24 hours after surgery, CRP at 3 days after surgery and the VAS score at 6 and 24 hours after surgery in the aged group were significantly higher than those in the middle-aged group (P < 0.05). In the aged group, weak correlations were found between the cortisol concentration 6 hours after THA and the IL-6 level 24 hours after THA (r = -0.37, P = 0.04) and between the IL-6 level 6 hours after THA and the VAS score 24 hours after THA (r = 0.42, P = 0.02). CONCLUSION Aged patients showed lower cortisol levels at 6 hours after surgery and higher IL-6 levels at 6 and 24 hours after surgery than middle-aged patients undergoing THA.