An elderly patient’s lactate level measured at the point of hospital admission does not predict mortality and complications following a hip fracture, a new study suggests.
Hip fracture is a serious condition in the elderly patient population: The rate of four-month mortality is approximately 20%, according to researchers from Lund University, in Sweden. More than 250,000 people aged 65 years or older are hospitalized for hip fractures annually in the United States, according to the Centers for Disease Control and Prevention. Falling causes more than 95% of hip fracture incidents, and the risk for hip fracture increases with age.
The researchers noted that some studies (J Trauma 2009;66:1040-1044 and Crit Care 2013;17:R197) have suggested that lactate levels exceeding the normal 2 to 2.5 mmol/L predict poor outcomes in multitrauma and ICU patients. The increased lactate levels might also help identify patients at high risk for death, and help clinicians to initiate treatment strategies to normalize lactate levels to improve outcomes. The researchers analyzed patient data collected from a prospective observational study to determine the usefulness of lactate level at admission for predicting mortality and complications in hip fracture patients.
“Other groups have looked at lactate levels in trauma patients and in septic patients, and they found that even relative hyperlactatemia does have some prognostic indications,” said Magnus Jonsson, MD, lead study author and a consultant anesthesiologist. “Our aim is to try to find something that can identify the patients who need more care and more attention during the hospital stay.”
The study included 1,012 patients (mean age, 83.5 years; 72% women). The types of hip fracture reported were 52% cervical, 42% trochanteric and 8% subtrochanteric. No patients had a systolic blood pressure below 90 mm Hg at admission. Data on venous lactate levels at admission and 30-day outcomes were available for 474 patients. The primary outcome measure was 30-day mortality using the cutoff of 2 mmol/L, suggested in the medical literature. Secondary measures were postoperative complications such as kidney injury, infection, thromboembolic events or cardiovascular events.
There were 39 deaths within 30 days in the group with lactate data. This group also had 114 patients who died or experienced postoperative complications. There were no significant differences in morbidity and mortality between the two groups. The researchers concluded that lactate level had limited clinical value.
“We found that lactate at admission is not very helpful. It does have some statistical significance, but clinical significance is doubtful,” Dr. Jonsson said.
The researchers also found that a lactate level of 2.8 mmol/L was the optimal threshold for predicting death. Levels greater than 2.8 were associated with a “modest increase in likelihood of death” (positive likelihood ratio, 3.7; 95% CI, 1.57-8.82). Levels less than 2.8 did not change the likelihood of death (negative likelihood ratio, 0.88; 95% CI, 1.77-1.01). The accuracy of this outcome measure was even lower when the standard threshold of 2 mmol/L was used.
Dr. Jonsson said he and his team are currently investigating if other predictors (e.g., biomarkers and Physiological and Operative Severity Score) may be applicable for this elderly patient population. The findings were presented at the 2015 annual meeting of the American Society of Anesthesiologists (abstract A2099).