ESTABLISHING THE RELATIVE ACCURACY OF 3 NEW DEFINITIONS OF THE ADULT-RESPIRATORY-DISTRESS-SYNDROME

Over the last few years, new definitions of the adult respiratory dist ress syndrome (ARDS) have been introduced that potentially identify pa tients earlier in their course of acute lung injury. However, these de finitions have never been compared with any of the older and potential ly stricter definitions of ARDS to determine if similar patients are e ventually identified. We compared new definitions of ARDS-as represent ed by the Lung Injury Score, a modified Lung Injury Score, and the Ame rican-European Consensus Conference definition-against stricter defini tion of ARDS to determine their accuracy. Design: Prospective. Setting : Intensive care unit (ICU) patients in a tertiary, university-affilia ted city hospital. Patients: ICU patients with clearly defined at-risk diagnoses for ARDS (group 1, n = 111) and general medical ICU patient s without clearly defined at-risk diagnoses for ARDS (group 2, n = 125 ). Measurements and Main Results: Measurements of hypoxemia, static re spiratory system compliance, positive end-expiratory pressure, radiogr aphic changes, and general demographic information were collected. The sensitivity, specificity, positive-predictive value, negative-predict ive value, and accuracy of all three new definitions were determined. Accuracy was defined as the true-positive plus the true-negative resul ts divided by the total number of patients. When compared with a stric ter definition of ARDS, all three definitions maintained a high degree of accuracy in those patients with a clearly defined at-risk diagnosi s (group 1): Lung Injury Score 90.0% (95% confidence interval 84-96); modified Lung Injury Score 97.3% (95% confidence interval 94-100), and the American-European Consensus Conference definition 97.3% (95% conf idence interval 94-100). For these at-risk patients, the accuracy of t he modified Lung Injury Score and the American-European Consensus Conf erence definition was significantly better than the Lung Injury Score when compared with the strict definition (p = .027 for both comparison s). Although all three definitions maintained an accuracy of >90% for general medical ICU patients (group 2), the low frequency of ARDS in t hese patients (3.4%) produced a low positive-predictive value for all three definitions. Conclusions: We conclude that the Lung Injury Score , the modified Lung Injury Score, and the American-European Consensus Conference definition identify similar patients, provided that these m ethods are applied to patients with clearly defined at-risk diagnoses for ARDS.