The Apache III prognostic system: customized mortality predictions for Spanish ICU patients.

OBJECTIVE

To customize the Acute Physiology and Chronic Health Evaluation (APACHE) III mortality equation for Spanish admissions to the intensive care unit (ICU) and evaluate its discrimination and calibration.

DESIGN

Prospective multicenter inception cohort study.

SETTING

86 ICUs located in all regions of Spain.

PATIENTS

10,929 adult patients selected by a systematic sampling method. All types of critical care patients were included, including coronary bypass patients, but excluding those with burn injury, those admitted for pacemaker implants, patients under 16 years of age, and patients with length of ICU stay < 6 h.

MEASUREMENTS AND RESULTS

Data collection in the first 24 h after patient admission included: APACHE III score, treatment location prior to ICU admission, and main ICU admission diagnosis. Using these variables, a model for predicting hospital mortality was constructed, adapted to Spain, and its discriminating ability was assessed by the area below the ROC curve, which was 0.83. The model was validated using the jacknife method and the area below the receiver operating characteristic (ROC) curve for the cross-validated predictions was 0.82. The percentage of patients correctly classified at 0.50 risk of death was 82.3%. Model calibration was evaluated by analysis of the agreement between the observed and cross-validated predicted mortality using the Hosmer-Lemeshow test, which gave a value of (H) 12.27, with no statistical significance, i.e., good calibration.

CONCLUSIONS

We have customized the APACHE III mortality prediction system for the Spanish population. This adapted model has demonstrated the requisite validation, calibration, and discrimination for its use among Spanish critical care patients.