A simple clinical predictive index for objective estimates of mortality in acute lung injury.
OBJECTIVE
We sought to develop a simple point score that would accurately capture the risk of hospital death for patients with acute lung injury (ALI).


METHODS
This is a secondary analysis of data from two randomized trials. Baseline clinical variables collected within 24 hours of enrollment were modeled as predictors of hospital mortality using logistic regression and bootstrap resampling to arrive at a parsimonious model. We constructed a point score based on regression coefficients.


METHODS
Medical centers participating in the Acute Respiratory Distress Syndrome Clinical Trials Network (ARDSnet).


METHODS
Model development: 414 patients with nontraumatic ALI participating in the low tidal volume arm of the ARDSnet Acute Respiratory Management in ARDS study. Model validation: 459 patients participating in the ARDSnet Assessment of Low tidal Volume and elevated End-expiratory volume to Obviate Lung Injury study. Model Validation: 459 patients participating in the ARDSnet Assessment of Low tidal Volume and elevated End-expiratory volume to Obviate Lung Injury trial.


METHODS
None.


RESULTS
Variables comprising the prognostic model were hematocrit <26% (1 point), bilirubin >or=2 mg/dL (1 point), fluid balance >2.5 L positive (1 point), and age (1 point for age 40-64 years, 2 points for age >or=65 years). Predicted mortality (95% confidence interval) for 0, 1, 2, 3, and 4+ point totals was 8% (5% to 14%), 17% (12% to 23%), 31% (26% to 37%), 51% (43% to 58%), and 70% (58% to 80%), respectively. There was an excellent agreement between predicted and observed mortality in the validation cohort. Observed mortality for 0, 1, 2, 3, and 4+ point totals in the validation cohort was 12%, 16%, 28%, 47%, and 67%, respectively. Compared with the Acute Physiology Assessment and Chronic Health Evaluation III score, areas under the receiver operating characteristic curve for the point score were greater in the development cohort (0.72 vs. 0.67, p = 0.09) and lower in the validation cohort (0.68 vs. 0.75, p = 0.03).


CONCLUSIONS
Mortality in patients with ALI can be predicted using an index of four readily available clinical variables with good calibration. This index may help inform prognostic discussions, but validation in nonclinical trial populations is necessary before widespread use.
Cooke
Colin R
CR
Division of Pulmonary and Critical Care Medicine , University of Washington, Seattle, WA, USA. crcooke@u.washington.edu
Shah
Chirag V
CV
Gallop
Robert
R
Bellamy
Scarlett
S
Ancukiewicz
Marek
M
Eisner
Mark D
MD
Lanken
Paul N
PN
Localio
A Russell
AR
Christie
Jason D
JD
D018806:APACHE; D055371:Acute Lung Injury / Q000401:mortality*; D000328:Adult; D000368:Aged; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis