Mortality risk stratification in elderly trauma patients based on initial arterial lactate and base deficit levels

Elderly trauma patients have worse outcomes than their younger counterparts. Early risk stratification remains difficult, particularly because traditional vital signs are less reliable. We hypothesized that arrival lactate and base deficit (BD) could be used to predict mortality in elderly trauma patients with a normal admission blood pressure. We retrospectively evaluated the prospectively collected trauma registry at our urban Level I trauma center between 2003 and 2009. Patients sustaining blunt trauma, age 55 years or older, with a systolic blood pressure 90 mmHg or higher, and who had arterial lactate and/or BD measured within 4 hours of arrival comprised the study group. Primary outcomes were in-hospital and 24-hour mortality. There were 364 patients with a lactate and 324 with a BD drawn. Patients with a lactate 2.5 mmol or greater were 3.7 times more likely to die than those with a lactate less than 2.5 mmol (95% CI, 1.6 to 8.2; P = 0.0018). The OR for mortality was 5.2 (95% CI, 2.5 to 11.2; P < 0.0001) in patients with a BD -4 or less. Elevated lactate and BD were even stronger predictors of early mortality (within first 24 hours). After increasing the hypotension threshold to a systolic blood pressure 110 mmHg or greater, lactate and BD remained highly predictive of in-hospital and 24-hour mortality.