Higher NLR, CAR, and SAA Levels Associated with Increased Readmission Risk in Acute Exacerbations of COPD: Study

"Elevated neutrophil-to-lymphocyte ratio (NLR), C-reactive protein to albumin ratio (CAR), and serum amyloid A (SAA) were linked to respiratory failure in acute exacerbations of COPD. Patients with higher levels faced a greater risk of readmission within a year. The combined use of these markers enhanced predictive accuracy (AUC: 0.717), highlighting their potential in clinical evaluation," the researchers reported.

The researchers note that chronic obstructive pulmonary disease (COPD) is a progressive lung condition characterized by persistent airflow limitation and inflammation. Acute exacerbations, often triggered by infections or environmental factors, can worsen symptoms and lead to respiratory failure, a life-threatening complication requiring immediate medical intervention. Identifying reliable biomarkers to predict such exacerbations remains a crucial aspect of COPD management.

Against the above background, Xiao-Hua Zhang, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, People’s Republic of China, and colleagues aimed to evaluate the ability of the neutrophil-to-lymphocyte ratio, C-reactive protein to albumin ratio, and serum amyloid A to predict AECOPD with respiratory failure.

For this purpose, the researchers conducted a retrospective study on 198 patients with AECOPD between December 2022 and May 2023. Patients were divided into two groups: an experimental group with respiratory failure (RF) (n = 70) and a control group without RF (n = 128). Baseline characteristics and inflammatory marker levels were compared, and their influence on one-year readmission risk was analyzed to evaluate the predictive value of NLR, CAR, and SAA in patients with AECOPD and RF.

The study led to the following findings:

• The experimental group had significantly higher levels of white blood cells, neutrophils, C-reactive protein (CRP), serum amyloid A (SAA), neutrophil-to-lymphocyte ratio (NLR), and C-reactive protein to albumin ratio (CAR) compared to the control group.
• There was a higher one-year readmission rate in the experimental group, with statistically significant differences.
• The areas under the receiver operating characteristic (ROC) curve for predicting AECOPD with respiratory failure were 0.705 for NLR, 0.659 for CAR, and 0.656 for SAA.
• When these three markers were combined, the ROC area under the curve increased to 0.717, showing statistical significance.

The researchers highlighted that the combined evaluation of inflammatory markers—NLR, CAR, and SAA— is crucial in assessing patients with AECOPD and respiratory failure. These markers provide a reliable reflection of systemic inflammation and serve as significant predictors of one-year readmission risk, offering valuable clinical insights for diagnosis and prognosis.

"Given their accessibility, this approach holds promise for broader application in primary healthcare settings. However, as the study was limited to a single-center retrospective analysis with a small sample size, further large-scale, multi-center prospective studies are needed to validate these findings," the researchers concluded.

Reference:

Zhang XH, Han MF, Teng XB, Shi JF, Xu XL. Combined Inflammatory Markers for Predicting Acute Exacerbations in Chronic Obstructive Pulmonary Disease With Respiratory Failure. J Inflamm Res. 2025;18:2513-2520https://doi.org/10.2147/JIR.S508048