Objective: To analyze and compare the prognostic value of the pediatric index of mortality (PIM) score and lactate values on admission to a pediatric intensive care unit (PICU).
Patients and methods: We performed a prospective study of 500 consecutive children: 237 girls (47.4 %) and 263 boys (52.6 %) with a mean age of 51.5 59.7 (range: 3 days-18 years) admitted to our PICU. PIM scores and blood lactate concentrations were determined on admission. The predictive ability of PIM and lactate concentrations in relation to mortality and length of stay in the PICU were analyzed.
Results: Thirty-six patients (7.2 %) died. According to the PIM score, the mean probability of death in children who died was 23.6 % 28.9, which was significantly higher than that in surviving children (3.4 % 7.3; p < 0.001). The area under the ROC curve for PIM was 0.81 0.03 (95 % CI: 0.74-0.89). Lactate level in nonsurvivors was 4.9 % 3.5 mmol/L, which was significantly higher than that in survivors (1.9 % 1.5 mmol/L; p < 0.001). The area under the ROC curve for blood lactate was 0.76 0.04 (95 % CI: 0.67-0.85). No statistically significant differences were found between either ROC curves. In survivors, a significant relationship was found between PIM score and length of stay in the PICU while in nonsurvivors an inverse relationship was found between blood lactate concentrations and length of stay.
Conclusions: Both PIM score and blood lactate concentrations on admission to the PICU have a moderate prognostic value in critically-ill children. The prognostic value of the PIM score is greater than that of blood lactate concentration but is more difficult to obtain, whereas blood lactate determination is fast and easy.