Evaluation of prognostic biomarkers for exacerbation frequency in patients with chronic obstructive pulmonary disease

Systemic inflammation is closely associated with acute exacerbations of chronic obstructive pulmonary disease and may reflect the risk of future exacerbations. Blood-based inflammatory biomarkers represent simple and practical tools for identifying patients at increased risk. The aim of this study was to evaluate the association between systemic inflammatory biomarkers measured during stable chronic obstructive pulmonary disease and overall exacerbation burden across Global Initiative for Chronic Obstructive Lung Disease stages.

This retrospective cohort study included 132 patients with chronic obstructive pulmonary disease followed for at least 2 years. Clinical, functional, and laboratory data obtained during clinically stable periods were analyzed. Systemic inflammatory indices (neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, systemic immune-inflammation index, systemic inflammation response index, aggregate index of systemic inflammation, and modified Glasgow prognostic score) were calculated. Exacerbation frequency was defined as the annualized number of moderate-to-severe exacerbations. Patients were classified according to Global Initiative for Chronic Obstructive Lung Disease groups A, B, and E, and associations between inflammatory biomarkers and clinical outcomes were evaluated using appropriate statistical methods, including receiver operating characteristic curve analyses.

Elevated levels of neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, systemic immune-inflammation index, aggregate index of systemic inflammation, modified Glasgow prognostic score, and C-reactive protein were significantly associated with increased exacerbation frequency and hospitalization rates in the overall cohort (all p<0.05), whereas systemic inflammation response index showed no significant association. Receiver operating characteristic analyses demonstrated moderate discriminative ability of C-reactive protein and inflammatory indices for predicting frequent exacerbations.

Systemic inflammatory biomarkers were associated with adverse clinical outcomes in patients with chronic obstructive pulmonary disease and were significantly related to exacerbation frequency and severity. These findings suggest that systemic inflammatory markers may be useful for overall clinical assessment and identifying patients at increased risk of exacerbations, rather than for stage-specific risk stratification.