Older Patients Are Immunocompromised by Cytokine Depletion and Loss of Innate Immune Function After HIP Fracture Surgery

Abstract

Purpose/Introduction: We have examined the immune status of elderly patients who underwent surgery for a hip fracture, an injury associated with poor postoperative outcomes, to identify specific immune defects. Methods: In a cohort observational study, 16 patients undergoing surgery for hip fractures had immune function evaluation prior to surgery, and then at 3 and 7 days postoperatively, using flow cytometry for phenotype and for monocyte and granulocyte phagocytic function and respiratory burst. Serum samples were stored and batch analyzed using a human cytokine 25-plex panel. Results: We report significant loss of innate immune function, related specifically to reduced granulocyte numbers by day 7 ( P < .0001, flow cytometry; P < .05 white blood cells), and although granulocyte ability to take up opsonized Escherichia coli was increased ( P < .05), the ability of those cells to generate a respiratory burst was reduced at days 3 and 7 ( P < .05). Monocyte respiratory burst was also significantly reduced ( P < .05). Serum cytokine levels indicated very poor T-cell function. Conclusion: We have demonstrated that the antimicrobial immune response is profoundly reduced after surgery in elderly patients with hip fractures. The effect was sustained up to 7 days postoperatively, identifying these patients as particularly vulnerable to bacterial infections.