Evaluation of predictive ability of APACHE II system and hospital outcome in Canadian intensive care unit patients

• Published in: Critical care medicine Vol. 23; no. 7; pp. 1177 - 1183
• Main Authors: Wong, David T, Crofts, Sally L, Gomez, Manuel, McGuire, Glenn P, Byrick, Robert J
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Williams & Wilkins 01-07-1995; Lippincott
• Subjects: Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; APACHE; Biological and medical sciences; Canada; Chi-Square Distribution; Clinical death. Palliative care. Organ gift and preservation; Critical Care - statistics & numerical data; Hospital Mortality; Hospitals, University - statistics & numerical data; Humans; Linear Models; Medical sciences; Middle Aged; Outcome Assessment (Health Care) - statistics & numerical data; Prognosis; Prospective Studies; Retrospective Studies; ROC Curve; Sensitivity and Specificity; Survivors - statistics & numerical data; United States; Canada; United States; Human; Correlation; Intensive care; Prognosis; Evaluation scale; Hospital environment; Severity score
• ISSN: 0090-3493; 1530-0293
• DOI: 10.1097/00003246-199507000-00005

OBJECTIVES To evaluate the ability of the Acute Physiology and Chronic Health Evaluation II (APACHE II) scoring system to predict patient outcome in two Canadian intensive care units (ICUs). To compare the severity of illness and outcome of Canadian ICU patients with existing United States data.
DESIGN Prospective data collection on 1,724 Canadian ICU patients for validation of the APACHE II system. Comparison of the outcome of Canadian ICU patients to retrospective United States data on 4,087 patients from the 1985 APACHE II multicenter study.
SETTING Canadian data from two university teaching hospital ICUs. United States data from 13 ICUs, ten of which were in university teaching hospitals.
PATIENTS Consecutive patients admitted to adult medical/surgical ICUs. Coronary care unit, neurosurgical and cardiac surgery patients were excluded.
INTERVENTIONS None.
MEASUREMENTS AND MAIN RESULTS For each patient, demographic data, diagnosis, APACHE II score and hospital survival data were collected. The predicted risk of death was calculated for each patient using the APACHE II risk of death equation. The accuracy in outcome prediction of the APACHE II system was assessed by means of the receiver operating characteristic curve, 2 times 2 decision matrices and linear regression analysis. The severity of illness and hospital mortality for the Canadian patients was compared with that of United States patients from the 1985 APACHE II multicenter study.In 1,724 Canadian ICU patients, the mean +/- SEM APACHE II score was 16.5 +/- 0.2. The predicted death rate was 24.7% and the observed death rate was 24.8%. Using receiver operating curve analysis, good correlation was found between predicted outcome and observed outcome. The area under the curve was 0.86. From the 2 times 2 decision matrix constructed for a predicted risk of death of 0.5, 83% of patients were correctly classified. The sensitivity was 50.9% and the specificity was 93.6%. When observed death rate was plotted against predicted death rate, linear regression analysis gave an r of.99.Canadian patients had a higher death rate and APACHE II score than the United States patients. After controlling for severity of illness using the APACHE II score, the Canadian and United States death rates were similar.
CONCLUSIONS The ability of the APACHE II system in predicting group outcome is validated in this Canadian ICU population by receiver operating characteristic curve, 2 times 2 decision matrices and linear regression analysis. The Canadian patients had a higher overall hospital death rate than the United States patients. After controlling for severity of illness using APACHE II scores, the hospital death rate was comparable between the Canadian and United States patients.(Crit Care Med 1995; 23:1177-1183)