Serum lactate as a marker of mortality in patients with hip fracture: A prospective study

Outcomes from patients suffering hip fracture remain poor, with 9% mortality at 30 days and 35% at 1 year. Despite robust guidelines these mortality rates have undergone little change. Admission serum lactate in patients with sepsis or suffering general trauma has been shown to be an indicator of adverse clinical outcomes. We investigated whether venous lactate can predict mortality for hip fracture patients. Over a 12-month period the admission venous lactate of all patients presenting to our institution with hip fractures was prospectively collated. Demographic and patient survivorship data were also prospectively recorded. Multivariate binary logistic regression and Cox proportional hazards ratio analysis was used to evaluate the relationship between admission venous lactate and 30-day mortality and early survivorship, whilst adjusting for age and gender. 770 patients were included in the study. The mean age was 80 years. The overall 30-day mortality for this cohort was 9.5%. Admission venous lactate was associated with early death. A 1mmol/L increase in venous lactate resulted in a 1.9 (95% CI 1.5-2.3 p<0.0001) fold increase in the odds of 30-day mortality and a 1.4 (95% CI: 1.2-1.6 p<0.0001) factor increase in the risk of death at any time after hip fracture. Admission venous lactate remained a predictor of mortality despite adjustment for patients American Society of Anesthesiologists (ASA) grade. Those with an admission serum lactate of 3mmol/L or greater were particularly at risk. This cohort had a 30-day mortality odds that was 5-fold higher than those whose level was less than 3mmol/L (p<0.0001) and at any-time risk of death that was 1.9 times higher (p<0.0001). Those with a level of less than 3mmol/L had a 30-day mortality of 6.8%. For those with an admission venous lactate of 3mmol/L or greater this was four times higher at 28%. The difference was statistically significant (p<0.0001). Elevated admission venous lactate following hip fracture is a predictor of early death. Venous lactate may be useful as a prognostic indicator or risk stratifier in patients with proximal femoral fractures.