Prognostic value of red cell distribution width/albumin ratio in patients with severe pneumonia-induced acute respiratory distress syndrome

Background The mortality rate of acute respiratory distress syndrome caused by severe pneumonia is high, and the correlation between red blood cell distribution width/albumin ratio and prognosis of acute respiratory distress syndrome caused by severe pneumonia is not yet clear.

Objective To investigate the prognostic value of the ratio of plasma red cell distribution width (RDW) to serum albumin (RAR) in patients with acute respiratory distress syndrome (ARDS) caused by severe pneumonia.

Methods Clinical data about patients with ARDS caused by severe pneumonia who visited the First Medical Center of Chinese PLA General Hospital from January 2016 to January 2022 were retrospectively analyzed. The patients were divided into survival group and death group according to the 28-day outcome, and general data, laboratory tests and treatment methods were collected. The relationship between RAR and 28-day mortality was evaluated by subject operation curve, single factor and multiple factor logistic regression and survival curve analysis.

Results A total of 296 patients were selected in this study, including 185 males and 111 females, with an average age of 69.7 ± 19.4 years. Among them, 149 (50.3%) cases were in the death group and 147 (49.7%) cases in the survival group. Compared with patients in the survival group, patients in the death group were older (72.9 ± 18.5 years vs 66.4 ± 19.9 years, P=0.005), had a higher proportion of patients with chronic renal failure (38.3% vs 25.2%, P=0.016), a higher APACHE II score (18.0 ± 5.7 vs 13.6 ± 5.7, P<0.001), a higher SOFA score (8.1 ± 3.2 vs 6.3 ± 3.1, P<0.001), and lower oxygenation index (141.2 ± 61.2 vs 170.0 ± 64.2, P<0.001). Multivariate regression analysis showed that RAR was independently associated with risk of 28-day death in ARDS patients caused by severe pneumonia. The cut-off value of RAR was 4.486. When RAR exceeded 4.486, the risk of 28-day death of ARDS patients caused by severe pneumonia was higher. The AUC was 0.723 (95% CI: 0.665-0.780), with a sensitivity of 0.799, and specificity of 0.558.

Conclusion The RAR value has a good predictive value for the 28-day prognosis of ARDS patients caused by severe pneumonia, which can be used as a biomarker to predict the prognosis of such patients.