Research Reports - Chronic inflammation after traumatic brain injury: Associations with outcome at 6-12 months postinjury
J Head Trauma Rehabil. 2014 Jun 4
Kumar RG(1), Boles JA, Wagner AK
OBJECTIVE:: Examine associations between chronic inflammatory profiles and
outcome 6 to 12 months following severe traumatic brain injury (TBI).
SETTING:: University-affiliated level 1 trauma center and community.
PARTICIPANTS:: Adults with severe TBI (n = 87); healthy controls (n = 7).
DESIGN:: Prospective cohort study.
MAIN MEASURES:: Glasgow Outcome Scale; serum cytokines (interleukin [IL]-1β,
IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12, tumor necrosis factor α), 2 weeks to
3 months, 4- to 6-month averages, 6- and 12-month levels.
RESULTS:: Serum levels of IL-1β, IL-6, IL-8, IL-10, and tumor necrosis factor α
were elevated over 3 months following TBI. Multivariate analysis showed that
increased cytokine load score was associated with a 1.21 (95% confidence
interval, 1.06-1.38) and 1.18 (95% confidence interval, 1.02-1.37) increase in
odds of unfavorable Glasgow Outcome Scale score at 6 and 12 months, respectively.
Also, elevated IL-6/IL-10 ratios were associated with increased odds of
unfavorable outcomes at 6 months (adjusted odds ratio = 1.76; 95% confidence
CONCLUSIONS:: Chronic inflammation has not been well characterized following TBI.
Our subacute cytokine load score classifies individuals at risk for unfavorable
outcomes following injury. Higher proinflammatory burden with IL-6, relative to
the anti-inflammatory marker IL-10, is significantly associated with outcome.
Further research should examine whether inflammatory genes and other inflammatory
biomarkers affect risk for unfavorable outcomes and TBI complications.