Decision support tool for early differential diagnosis of acute lung injury and cardiogenic pulmonary edema in medical critically ill patients

Background: At the onset of acute hypoxic respiratory failure, critically ill patients with acute lung injury (ALI) may be diffi cult to distinguish from those with cardiogenic pulmonary edema (CPE). No single clinical parameter provides satisfying prediction. We hypothesized that a combination of those will facilitate early differential diagnosis. Methods: In a population-based retrospective development cohort, validated electronic surveillance identifi ed critically ill adult patients with acute pulmonary edema. Recursive partitioning and logistic regression were used to develop a decision support tool based on routine clinical information to differentiate ALI from CPE. Performance of the score was validated in an independent cohort of referral patients. Blinded post hoc expert review served as gold standard. Results: Of 332 patients in a development cohort, expert reviewers(κ, 0.86) classifi ed 156 as having ALI and 176 as having CPE. The validation cohort had 161 patients (ALI 5 113, CPE 5 48). The score was based on risk factors for ALI and CPE, age, alcohol abuse, chemotherapy, and peripheral oxygen saturation/F IO 2 ratio. It demonstrated good discrimination (area under curve [AUC] 5 0.81; 95% CI, 0.77-0.86) and calibration (Hosmer-Lemeshow [HL] P 5.16). Similar performance was obtained in the validation cohort (AUC 5 0.80; 95% CI, 0.72-0.88; HL P 5.13). Conclusions: A simple decision support tool accurately classifi es acute pulmonary edema, reserving advanced testing for a subset of patients in whom satisfying prediction cannot be made. This novel tool may facilitate early inclusion of patients with ALI and CPE into research studies as well as improve and rationalize clinical management and resource use.