Prognostic significance of serum lactic acid in evaluation of acute paraquat poisoning patients

Abstract

To discuss the role of serum lactic acid (Lac) level in evaluation of prognosis of acute paraquat poisoning (APP) patients. Clinical data from 168 APP patients were retrospectively analyzed. The serum Lac level and the plasma paraquat concentrations at admission were collected, and the severity index of paraquat poisoning (SIPP) were calculated. The patients were divided into <10, 10-50, ≥50 h×mg×L(-1) groups on the basis of SIPP. The correlation between Lac and SIPP was analyzed, as well as the role in evaluating prognosis. The higher the SIPP level, the higher the Lac level [2.00 (1.50, 2.83) mmol/L, 3.10 (1.73, 5.15) mmol/L, 8.95 (5.90, 13.10) mmol/L, all P<0.05]; Lac was correlated positively with SIPP (r=0.569, P<0.05). The higher the SIPP, the higher the mortality of patients [17.4% (15/86), 61.5% (24/39), 97.7% (42/43), all P<0.05]. The survival days of SIPP≥50 h×mg×L(-1) group was shorter than that in SIPP<10 h×mg×L(-1) group and 10-50 h×mg×L(-1) group [2.0 (1.0, 3.0) days vs. 9.0 (4.0, 11.0) days and 5.0 (3.0, 10.0) days, both P<0.05]. A negative correlation was found between Lac, SIPP and survival days in non-survivors (r1=-0.778, r2=-0.621, both P<0.05). Logistic regression analyses showed either Lac or SIPP was of prognostic significance [odds ratio (OR) of Lac: 1.758, 95% confidence interval (95%CI) 1.278-2.417;OR of SIPP: 1.063,95%CI 1.025-1.103, both P=0.001]. The area under the receiver operating characteristic curve (ROC curve) of Lac, SIPP and prognosis were 0.885 and 0.897 respectively (both P<0.05), Lac≥3.35 mmol/L was the best cut-off value, the sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio and accuracy for predicting the death were 74.07%, 90.80%, 88.24%, 79.00%, 8.056, 0.286 and 82.74% respectively; the evaluation value was closed to SIPP≥13.83 h×mg×L(-1) (77.78%, 91.95%, 90.00%, 81.63%, 9.677, 0.242 and 85.12%, respectively). The change in serum Lac level has evaluation value of the severity and prognosis for APP patients, and Lac≥3.35 mmol/L can be made as a simple and easy indicator for prognosis of APP patients.