Value of radiographic assessment of lung edema score in evaluating the severity and prognosis of patients with acute respiratory distress syndrome

OBJECTIVE To explore the value of radiographic assessment of lung edema (RALE) score in evaluating the severity and prognosis of patients with acute respiratory distress syndrome (ARDS). METHODS A retrospective study was conducted. Patients with ARDS admitted to the department of intensive care unit (ICU) of Affiliated Nantong Third Hospital of Nantong University from January 2016 to November 2020 were enrolled. Clinical data of those patients were collected, and two senior radiologists who did not know the outcome of the patients independently scored each chest radiograph, the mean value of which was taken as the RALE score. The patients were divided into death group and survival group according to the 28-day prognosis. The differences of the basic data, PaO2/FiO2, sequential organ failure assessment (SOFA) score, acute physiology and chronic health evaluation II (APACHE II) score and RALE score between groups were analyzed. ARDS patients were classified according to the Berlin standard and RALE scores were compared between groups. Then, the correlations between RALE score and PaO2/FiO2, SOFA score, APACHE II score were analyzed. The prognostic capacity of RALE score for 28-day prognosis of ARDS patients were analyzed by Kaplan-Meier survival curve. RESULTS Of the 98 ARDS patients, 62 were included in the final analysis, 39 patients survived and 23 patients died. The 28-day mortality was 37.1%. Compared with the survival group, patients in the death group were older (years old: 72.83±12.21 vs. 64.44±14.68), had lower PaO2/FiO2 [mmHg (1 mmHg = 0.133 kPa): 122.66±48.32 vs. 150.26±50.40], and higher SOFA score and greater difference of RALE score between the third day and the first day after admission (D3-D1 RALE score) (SOFA score: 11.26±3.91 vs. 9.04±3.72, D3-D1 RALE score: 1.35±6.42 vs. -2.74±7.35), with statistically significant differences (all P < 0.05). However, there were no significant differences in gender, cause of ARDS, APACHE II score, and RALE scores on the first and the third day of admission (D1 RALE, D3 RALE) between the two groups. Among the 62 patients, there were 11 mild cases (17.7%), 36 moderate cases (58.1%), and 15 severe cases (24.2%). The D1 RALE score of patients with mild and moderate ARDS were lower than those of patients with severe ARDS (19.09±3.65, 22.58±6.79 vs. 27.07±5.23, both P < 0.05). Correlation analysis showed that D1 RALE score was negatively correlated with PaO2/FiO2 (r = -0.385, P = 0.002), and positively correlated with SOFA score and APACHE II score (r1 = 0.433, r2 = 0.442, both P < 0.001). Kaplan-Meier survival curve analysis showed that the 28-day survival rate of ARDS patients in D3-D1 RALE score ≥ -1 group was significantly higher than that in D3-D1 RALE score < -1 group (73.08% vs. 55.56%; log-rank test: χ2 = 3.979, P = 0.046). CONCLUSIONS The RALE score is a simple and reliable non-invasive evaluation index, which can be used to evaluate the severity of ARDS patients. The difference of RALE score in early stage is helpful to identify ARDS patients with poor prognosis.