Early Changes Over Time in the Radiographic Assessment of Lung Edema Score Are Associated With Survival in ARDS

Abstract

Background: The Radiographic Assessment of Lung Edema (RALE) score is associated with the severity of ARDS, and treatments targeted at reducing pulmonary edema such as conservative fluid management cause a reduction in RALE score over time.

Research question: Are early changes in RALE score over time associated with survival in patients with ARDS?

Study design and methods: Data from patients enrolled in three centers in the Lung Imaging for Ventilation sEtting in ARDS (LIVE) trial with available chest radiographs at baseline (day 0) and days 2 or 3 were used. The RALE was scored by two independent reviewers. The primary end point was death by day 90, considering RALE score both at baseline and as a time-varying covariate in a marginal Cox survival model.

Results: RALE was scored from 135, 64, and 88 radiographs on days 0, 2, and 3, respectively. Both baseline RALE (hazard ratio [HR] for each one-point increment, 1.04; 95% CI, 1.01-1.08; P = .006) and the change in RALE over time (HR for each one-point decrease per unit of time, 0.99; 95% CI, 0.99-0.99; P = .03) were associated with death by day 90, even after adjustment for age, sex, BMI, Simplified Acute Physiology Score II, vasopressor use, and total volume of fluids received since study entry.

Interpretation: The change in RALE during the first days after ARDS onset is independently associated with survival and may be useful as a surrogate end point in future clinical trials of new therapeutics in ARDS.

Keywords: ARDS; radiographic score; survival; treatable trait.

Figure 1

Flow of patients from the LIVE trial who were included in the secondary RALE score analysis. CHU = Centre Hospitalier Universitaire; LIVE = Lung Imaging for Ventilation sEtting in ARDS; RALE = Radiographic Assessment of Lung Edema.

Figure 2

Kaplan-Meier failure estimates curves of the probability of nonsurvival from study entry to day 90, as stratified by quartiles of the RALE score. Quartile 1: RALE score < 17; quartile 2, 17 ≤ RALE score < 23; quartile 3, 23 ≤ RALE score < 30; quartile 4, RALE score ≥ 30. See Figure 1 legend for expansion of abbreviation.

Figure 3

Kaplan-Meier failure estimates curves of the probability of nonsurvival from study entry to day 90, as stratified by the change in RALE score between day 0 and day 3 (decrease in RALE score [red line] vs increase or no change in RALE score [blue line]); n = 88 available for multivariable complete case analysis). See Figure 1 legend for expansion of abbreviation.