Nicolás Serrano, Eliseo J Plasencia, Juan José Jiménez, Jose María De la Rosa, Javier Málaga, Maria Teresa Brouard, Maria Luisa Mora.
Servicio de Medicina Intensiva, Hospital Universitario de Canarias, La Laguna, Tenerife, Spain.

• Supported by a Grant of Research from the Health Administration of the Autonomic Govern of the Canary Islands, Spain.
• Presented to the 4th Congress of the Euroacademy for Multidisciplinary Neurotraumatology.

OBJECTIVE: To validate in our setting the performance of the general severity systems Acute Physiology and Chronic Health Evaluation II (APACHE II), Simplified Acute Physiology Score II (SAPS II), and Mortality Probability Models II (MPM II) for head trauma patients.

PATIENTS AND METHODS: Patients (n = 85, 18% female and 82% male, mean age±SD = 34±21 years) who were diagnosed with head trauma (with/without multiple trauma), leading to intensive care unit (ICU) admission, and who were not brain dead at the time of arrival, were prospectively studied to evaluate the performance of the severity systems APACHE II, SAPS II, MPM II-0 (at ICU admission), MPM II-24 (at 24 hours of ICU admission), by means of calibration and discrimination tests. Discrimination was compared measuring the area under the receiver operating characteristic curve (AUC ROC) and the percent correct classification at the cut-point 0.5. Calibration was assessed using the Hosmer-Lemeshow (H-L) chi-square statistics.

RESULTS: Because the follow-up of the first 2/3 of the sample until hospital discharge revealed no new hospital deaths after ICU discharge, mortality at the time of ICU discharge (20 patients, 23.5%) was finally assumed as the only outcome measure in head trauma patients.

Overall mortality predictions by APACHE II SAPS II, MPM II-0, and MPM II-24 were 16.02, 22.59, 31.35, and 29.91 respectively, against the actually observed 20 deaths.

The discrimination of APACHE II was only sligthly better than SAPS II:
 

However, calibration of SAPS II was quite superior to APACHE II and also better than MPM II systems:
 

CONCLUSIONS: The APACHE II, SAPS II, and MPM II systems can provide an adequate estimation of the mortality experienced in patients with head trauma. In our setting, the SAPS II system seems to perform better than MPM II and APACHE II in these patients. APACHE II and MPM II are also appropriate tools to assess severity of illness in head trauma patients.