Systemic immune-inflammation index and neutrophil-to-lymphocyte ratio as biomarkers for acute exacerbation of elderly patients with chronic bronchitis

Abstract

Objectives: To evaluate the clinical utility of the systemic immune‑inflammation index (SII) and neutrophil‑to‑lymphocyte ratio (NLR) as predictive biomarkers for acute exacerbation in elderly patients with chronic bronchitis (CB).

Methods: This retrospective cross‑sectional study involved 215 elderly patients with CB. Patients were divided into two groups based on clinical presentation: stable CB (n = 93) and acute exacerbation of chronic bronchitis (AECB) (n = 122). Baseline clinical parameters and laboratory indicators were collected and analyzed.

Results: The AECB group exhibited significantly lower lymphocyte count and reduced serum albumin level, alongside significantly increased levels of C‑reactive protein (CRP), NLR, and SII (p < 0.001) compared with the stable CB group. Multivariate logistic regression indicated that decreased albumin (odds ratio (OR) = 0.605), and higher values of CRP (OR = 1.058), NLR (OR = 1.505), and SII (OR = 1.004) were all significantly associated with the likelihood of AECB. Among individual markers, SII showed the highest discriminatory capacity (AUC = 0.856), with albumin (AUC = 0.833), NLR (AUC = 0.823), and CRP (AUC = 0.822) performing comparably. Combining the four indicators resulted in a significantly enhanced diagnostic estimate (AUC = 0.970), achieving a sensitivity of 86.9% and a specificity of 96.8%.

Conclusions: NLR and SII can serve as valuable inflammatory indicators for acute exacerbations in older patients with CB. When used alongside albumin and CRP, these markers modestly improve the ability to distinguish between stable and exacerbated states, offering supportive value in the early clinical assessment of AECB risk.