Associations of Plasma Lipids with Traumatic Brain Injury Outcomes: A Transforming Research and Clinical Knowledge in Traumatic Brain Injury Study.

Hypocholesterolemia has been observed in acute trauma, but less is known about lipid levels in acute traumatic brain injury (TBI). Our objectives were to (1) compare day 1 post-injury lipid levels from individuals with acute TBI to orthopedic trauma and healthy controls and (2) investigate associations of day 1 post-TBI lipid levels with clinical outcomes over the first-year post-injury. A subset of 266 participants with TBI, 68 orthopedic trauma controls, and 58 healthy controls from the Transforming Research and Clinical Knowledge in TBI Study were included in analyses. Plasma total cholesterol and triglycerides were measured using the enzymatic colorimetric method, and high-density lipoprotein (HDL) was measured via direct homogeneous/enzymatic colorimetric methods. Low-density lipoprotein (LDL) values were calculated using the Friedewald formula. The primary TBI outcome was the Glasgow Outcome Scale-Extended (dichotomized as favorable [score = 5-8] versus unfavorable [score = 1-4] outcome and complete [score = 8] versus incomplete [score = 1-7] recovery; administered at 2 weeks, 3 months, 6 months, and 1-year post-injury). Age- and sex-adjusted total cholesterol and LDL cholesterol were lower among participants with TBI compared with orthopedic trauma and healthy controls (total cholesterol: 116.7 mg/dL [95% confidence interval or CI = 112.1-121.3] versus 137.8 mg/dL [95% CI = 129.1-146.5] and 130.2 mg/dL [95% CI = 120.6-139.9]; LDL cholesterol: 59.3 mg/dL [95% CI = 55.8-62.9] versus 77.7 mg/dL [95% CI = 71.1-84.3] and 72.4 mg/dL [95% CI = 65.1-79.7]). Adjusted levels of HDL cholesterol and triglycerides were similar by group. Among participants with TBI, higher day 1 post-injury total cholesterol, LDL, and triglyceride levels were associated with greater adjusted odds of favorable versus unfavorable outcome after injury. In conclusion, our study found that day 1 post-injury levels of total and LDL cholesterol were lower among individuals with TBI compared with both orthopedic trauma and healthy controls. Furthermore, our results suggest that individuals who did not have acutely low total cholesterol and LDL cholesterol, and, to a lesser extent, triglycerides, had better functional outcomes over the first-year post-TBI.