Body mass index interaction effects with hyperglycemia and hypocholesterolemia modify blunt traumatic brain injury outcomes: a retrospective study.

INTRODUCTION There is controversy regarding obesity or body mass index (BMI) effects on postinjury mortality and mechanical ventilation. The aim was to assess outcome associations with BMI and postinjury blood glucose and cholesterol. METHOD Adult blunt traumatic brain injury patients admitted to a level I trauma center and requiring ≥ 3 days of intensive care were investigated. Admission blood glucose and day-4 total cholesterol were captured from the medical records. Cholesterol ratio was calculated by dividing day-4 values by published national normative levels according to sex, age, and injury date. RESULTS The parent cohort included 588 patients. The ventilator days ≥ 10 or died group, when compared to the ventilator days < 10 and lived group, had higher Injury Severity Score (ISS) (29.2±9.9 versus [vs.] 23.7±9.7, P < 0.0001), BMI (27.9±6.8 vs. 26.0±5.5, P = 0.0002), and admission glucose (182.6±79 vs. 155.4±59 mg/dl, P < 0.0001, n = 476) and lower emergency department Glasgow Coma Scale score (ED GCS) (6.9±4.7 vs. 10.3±5.0, P < 0.0001) and cholesterol ratio (0.64±0.2 vs. 0.70±0.2, P = 0.0018, n = 364). The ventilator days ≥ 10 or died group had independent associations with increased ISS (P = 0.0709), decreased ED GCS (P = 0.0078), and increased BMI÷cholesterol ratio (P = 0.0003). The ventilator days ≥ 10 or died group had independent associations with increased ISS (P = 0.0013), decreased ED GCS (P < 0.0001), and increased BMI × glucose (P < 0.0001). Ventilator days were increased with higher ISS (P < 0.0001), BMI (P = 0.0014) and glucose (P = 0.0031) and with lower ED GCS (P < 0.0001) and cholesterol ratio (P = 0.0004). Ventilator days had independent associations with increased ISS (P < 0.0001), decreased ED GCS (P = 0.0041), and increased BMI÷cholesterol ratio (P = 0.0010). Ventilator days had independent associations with increased ISS (P < 0.0001), decreased ED GCS (P < 0.0001), and increased BMI × glucose (P = 0.0041). CONCLUSION For TBI patients, valid risk assessment measurements include ISS (anatomic injury burden), ED GCS (brain function), BMI (preinjury weight status), admission glucose (postinjury metabolism), and day-4 cholesterol ratio (postinjury inflammation).