Prognostic value of lactate levels and lactate clearance in sepsis and septic shock with initial hyperlactatemia

The 2016 Surviving Sepsis Campaign guidelines suggest guiding resuscitation to normalize lactate levels in patients with sepsis-associated hyperlactatemia as a marker of tissue hypoperfusion. This study evaluated the prognostic value of lactate levels and lactate clearance for 30-day mortality in patients with sepsis and septic shock diagnosed in the emergency department. We performed a retrospective cohort study of sepsis patients with initial lactate levels of ≥2 mmol/L. All patients met the Sepsis-3 definitions. The prognostic value of 6-hour lactate levels, 6-hour lactate clearance, 6-hour lactate metrics (≥2 mmol/L), and lactate clearance metrics (<10%, <20%, and <30%) was evaluated. We compared the sensitivity and specificity between metrics. Of the 363 sepsis and septic shock patients, 148 died (30-day mortality: 40.8%). Nonsurvivors had significantly higher 6-hour lactate levels and lower 6-hour lactate clearance than those of survivors. Six-hour lactate levels and 6-hour lactate clearance were associated with 30-day mortality after adjusting for potential confounders (odds ratio, 1.191 [95% confidence interval (CI), 1.097–1.294] and 0.989 [0.983–0.995], respectively). Six-hour lactate levels had better prognostic value than 6-hour lactate clearance (area under the curve, 0.720 [95% CI, 0.670–0.765] vs 0.656 [0.605–0.705]; P  = .02). Six-hour lactate levels of ≥3.5 mmol/L and 6-hour lactate clearance of <24.4% were the optimal cut-off value in predicting the 30-day mortality. The prognostic value of 6-hour lactate metrics and 6-hour lactate clearance metrics did not differ. Six-hour lactate levels (≥2 mmol/L) had the highest sensitivity (89.2%). Six-hour lactate levels proved to be more accurate in predicting 30-day mortality than 6-hour lactate clearance and initial lactate levels.