Time-course of cytokines during delirium in elderly patients with hip fractures

To compare the time-course of cytokine levels in patients with and without delirium and investigate differences in cytokine concentrations in delirium subtypes.

Prospective cohort study.

Academic Medical Center, Amsterdam, 2005 through 2007.

Patients aged 65 and older admitted for surgery after hip fracture.

Experienced geriatric physicians used the Confusion Assessment Method to assess delirium and the Delirium Symptom Interview to assess delirium subtype. Tumor necrosis factor alpha (TNF-alpha) and interleukin (IL)-1beta, IL-6, IL-8, IL-10, and IL-12 were assayed in repeated serum samples using a cytometric bead array immunoassay.

Of 221 admitted patients, 98 (mean age 84, 50 patients with delirium) were included, resulting in a total of 324 samples. Ninety-six percent of these samples had TNF-alpha, IL-1beta, and IL-10 levels below the reliable detection level. Differences between patients with and without delirium were observed in IL-6 (median 51 vs 36 pg/mL, P=.01) and IL-8 (median 15 vs 9 pg/mL, P=.03) levels. Changes over time in IL-6 and IL-8 levels in patients with delirium differed significantly from changes in levels in patients without delirium. The highest levels of IL-6 were present during delirium, and the highest levels of IL-8 were present before the development of delirium. Patients with the hyperactive (median 71 pg/mL) or mixed (median 73 pg/mL) subtype of delirium had higher IL-6 levels than patients with hypoactive delirium (median 16 pg/mL) (P=.02).

IL-6 and IL-8 may contribute to the pathogenesis of postoperative delirium in elderly people. IL-6 may play a role in the hyperactive behavior of delirium.