Prognostic value of blood-cell-derived composite inflammatory indices in hospitalized patients with acute exacerbation of bronchiectasis: a single-center retrospective cohort study

Abstract

Background Acute exacerbation of bronchiectasis (AEB) is closely linked to prolonged hospitalization, intensive care unit (ICU) admission and recurrent readmission. Several blood-cell-derived inflammatory indices, including Neutrophil to lymphocyte ratio (NLR), Platelet to Lymphocyte Ratio (PLR), Systemic Inflammatory Response Index (SIRI), Systemic Immune Inflammation index (SII) and Pan immune Inflammation Value (PIV) have shown prognostic potential in respiratory diseases, yet comparative evidence in large AEB cohorts remains insufficient. Objective To compare the prognostic performance of NLR, PLR, SIRI, SII andPIV for hospital-related adverse outcomes in hospitalized AEB patients. Methods This single-center retrospective study enrolled 3,116 hospitalized patients with AEB. Data were extracted from electronic medical records. The primary endpoint was length of hospital stay (LOS), while secondary endpoints included ICU admission and 1-year readmission. Spearman correlation, multivariable regression analyses, receiver-operating-characteristic (ROC) curves, Kruskal–Wallis H test, and Cochran-Armitage trend test were applied. Results The median age was 61 years and 56.68% of participants were female. ICU admission and 1-year readmission rates were 2.44% and 42.97%, respectively. NLR correlated with LOS ( ρ = 0.258, P < 0.001). After adjustment, each 1-standard-deviation (SD) increase in NLR was associated with a 13.9% longer hospital stay (1.139, 95%CI 1.122–1.156). All five indices were associated with ICU admission (per-SD ORs 1.17–1.61) and INR had highest predictive accuracy (AUC = 0.782, bootstrap-corrected 0.779). All five were also associated with 1-year readmission, though discrimination was low (AUC < 0.62), with PIV the weakest. A dose-response trend across NLR quartiles was evident. CRP correlated with NLR ( ρ = 0.506, 0.411) and LOS ( ρ = 0.199, 0.132) but, being incompletely recorded, were analyzed by correlation only and were not entered into adjusted models. Time-period stratified analyses (2014–2018 vs. 2019–2024) yielded directionally consistent results. Conclusions NLR exhibits superior prognostic performance compared with PLR, SIRI, SII, and PIV in AEB patients. As a cost-effective and readily available biomarker, NLR is well-suited for in-hospital risk stratification of AEB patients, with associations robust to time-period stratification.