Evaluation of prognostic indexes in critical acute renal failure patients

Abstract

Objective. To study different prognostic indexes in acute renal failure (ARF) patients admitted to an intensive care unit (ICU). Design. Prospective, cohort study. Individual Severity Score-Acute Tubular Necrosis (ISS-ATN) obtained prospectively and retrospectively, Acute Physiologic and Chronic Health Evaluation (APACHE II) Score, APACHE II Risk, Lung Injury Score (LIS), and Number of Organ Failures (NOF) were calculated for each patient. the outcome analyzed was death in the ICU. Discrimination was evaluated by the area under the receiver operator characteristic curve (AUC). for calibration analysis, the chi-square goodness-of-fit test was used to compare predicted mortality, calculated by ISS-ATN (obtained prospectively or retrospectively) and APACHE II risk, with observed mortality. Setting. ICU, Sao Rafael Hospital, Salvador-BA, Brazil. Patients. Seventy-six ARF patients admitted to the ICU within 6 months. Interventions. Surgical and medical procedures. Measurements and Results. the observed AUC was 0.69 for LIS, 0.73 for prospective ISS-ATN, 0.75 for retrospective ISS-ATN, 0.76 for APACHE II Score, 0.78 for APACHE II Risk, and 0.88 for NOF. These areas were significantly different from 0.5 (p <.001). There was no difference between the observed and expected death rate calculated by ISS-ATN. However, APACHE II underestimated the observed mortality (p <.001). Conclusion. the prognostic indexes studied showed good discriminative power. However, APACHE II was not well calibrated in contrast to the good calibration of ISS-ATN.