# Utility of the Red Cell Distribution Width-to-Albumin Ratio in Predicting Short-Term Mortality in Acute Exacerbations of Chronic Obstructive Pulmonary Disease: A Prospective Observational Study

## TL;DR

This study shows that a blood test measuring red cell distribution width-to-albumin ratio can accurately predict short-term death risk in patients with severe chronic lung disease flare-ups.

## Contribution

Demonstrates RAR as a novel, accessible biomarker for predicting 28-day mortality in ICU patients with acute COPD exacerbations.

## Key findings

- A RAR threshold of >5.43%dL/g predicted 28-day mortality with 95.45% sensitivity and 95.08% specificity.
- High RAR patients had 87.5% mortality versus 1.69% in low RAR patients (P < 0.001).
- RAR and lactate were the only independent predictors of mortality in multivariate analysis.

## Abstract

Background

Acute exacerbation of chronic obstructive pulmonary disease (ECOPD) significantly contributes to intensive care unit (ICU) admissions and short-term mortality. The red cell distribution width-to-albumin ratio (RAR) has emerged as a potential biomarker for systemic inflammation and adverse outcomes. This study aimed to assess the diagnostic value of baseline RAR in predicting 28-day all-cause mortality in ICU-admitted patients with acute ECOPD.

Methodology

In a prospective, observational design, 83 consecutive patients admitted with moderate to severe ECOPD were enrolled. Baseline clinical data, laboratory parameters, and clinical severity scores were collected. Patients were followed up for 28 days. The primary outcome was 28-day all-cause mortality. Receiver operating characteristic (ROC) analysis was used to determine the baseline optimal RAR cut-off.

Results

A baseline RAR threshold of >5.43%dL/g showed excellent predictive performance for 28-day mortality (area under the receiver operating characteristic (AUROC): 0.979; sensitivity: 95.45%; specificity: 95.08%). Mortality was significantly higher in the high RAR group (87.5%) when compared to the low RAR group (1.69%) (P < 0.001). Kaplan-Meier survival analysis confirmed significantly improved survival in patients with lower RAR. On multivariate analysis, only baseline lactate (P = 0.011) and RAR (P = 0.008) independently predicted mortality. RAR had a poor predictive value for the failure of non-invasive ventilation.

Conclusions

Baseline RAR is a simple, accessible, and effective biomarker for predicting short-term mortality in ECOPD. Its integration into early ICU risk stratification protocols warrants further validation in larger, multi-center cohorts.