Abstract and Introduction
Objective: The Lung Injury Prediction Score identifies patients at risk for acute respiratory distress syndrome in the emergency department, but it has not been validated in non-emergency department hospitalized patients. We aimed to evaluate whether Lung Injury Prediction Score identifies non-emergency department hospitalized patients at risk of developing acute respiratory distress syndrome at the time of critical care contact.
Design: Retrospective study.
Setting: Five academic medical centers.
Patients: Nine hundred consecutive patients (≥ 18 yr old) with at least one acute respiratory distress syndrome risk factor at the time of critical care contact.
Measurements and Main Results: Lung Injury Prediction Score was calculated using the worst values within the 12 hours before initial critical care contact. Patients with acute respiratory distress syndrome at the time of initial contact were excluded. Acute respiratory distress syndrome developed in 124 patients (13.7%) a median of 2 days (interquartile range, 2–3) after critical care contact. Hospital mortality was 22% and was significantly higher in acute respiratory distress syndrome than non-acute respiratory distress syndrome patients (48% vs 18%; p < 0.001). Increasing Lung Injury Prediction Score was significantly associated with development of acute respiratory distress syndrome (odds ratio, 1.31; 95% CI, 1.21–1.42) and the composite outcome of acute respiratory distress syndrome or death (odds ratio, 1.26; 95% CI, 1.18–1.34). A Lung Injury Prediction Score greater than or equal to 4 was associated with the development of acute respiratory distress syndrome (odds ratio, 4.17; 95% CI, 2.26–7.72), composite outcome of acute respiratory distress syndrome or death (odds ratio, 2.43; 95% CI, 1.68–3.49), and acute respiratory distress syndrome after accounting for the competing risk of death (hazard ratio, 3.71; 95% CI, 2.05–6.72). For acute respiratory distress syndrome development, the Lung Injury Prediction Score has an area under the receiver operating characteristic curve of 0.70 and a Lung Injury Prediction Score greater than or equal to 4 has 90% sensitivity (misses only 10% of acute respiratory distress syndrome cases), 31% specificity, 17% positive predictive value, and 95% negative predictive value.
Conclusions: In a cohort of non-emergency department hospitalized patients, the Lung Injury Prediction Score and Lung Injury Prediction Score greater than or equal to 4 can identify patients at increased risk of acute respiratory distress syndrome and/or death at the time of critical care contact but it does not perform as well as in the original emergency department cohort.
The acute respiratory distress syndrome (ARDS) is associated with high morbidity and mortality worldwide.[1,2] Lung protective ventilation is the only treatment available to lower the risk of death with ARDS. Given the lack of effective treatments, the focus of the scientific and clinical communities has shifted to ARDS prevention with the goal of delivering interventions in the pre-ARDS state to halt the progression to ARDS in patients at risk.[4,5] This is the objective of the National Heart, Lung, and Blood Institute (NHLBI)-funded Prevention and Early Treatment of Acute Lung Injury (PETAL) network that focuses on clinical trials aimed at the prevention and early treatment of ARDS. ARDS does not develop in the majority of patients with established predisposing conditions.[6,7] To minimize harm from exposure to therapeutic strategies, we need tools for early identification of patients at higher risk of ARDS for whom preventive interventions have a favorable risk-to-benefit ratio. The Lung Injury Prediction Score (LIPS) is a validated prediction model that uses clinical data at the time of presentation to the emergency department (ED) to identify patients at high risk for ARDS.[6,8,9] A LIPS greater than or equal to 4 is currently used to enroll high-risk patients in clinical trials on ARDS prevention.[10–12]
Although the LIPS successfully stratifies patients at higher risk for ARDS at the time of ED presentation, it is not validated for patients at risk of ARDS in the hospital wards. Half of the patients with an ARDS-predisposing condition on hospital admission are not admitted to an ICU[13,14] and over half of the patients with sepsis or pneumonia are initially treated in the hospital wards.[15–17] Because the LIPS uses criteria "at the time of hospital admission," it is not clear how well it performs in patients who develop predisposing conditions after the initial ED presentation or who deteriorate clinically after hospital admission requiring critical care evaluation or ICU transfer. Such validation is important to use the LIPS in prevention trials to identify ward patients at higher risk of ARDS.
Therefore, the purpose of this study is to validate the LIPS in non-ED hospitalized patients at higher risk of ARDS when they require critical care evaluation from areas of the hospital other than the ED.
Crit Care Med. 2016;44(12):2182-2191. © 2016