Neutrophil-to-albumin ratio (NAR) as a predictor of pulmonary cavitation in pediatric and adolescent patients with active tuberculosis: a retrospective cohort study

Pulmonary cavitation is a characteristic feature of severe tuberculosis (TB) that substantially influences both disease transmission and clinical outcomes. Although immunonutritional imbalances have been implicated in the pathogenesis of TB, the role of composite biomarkers, such as the neutrophil-to-albumin ratio (NAR), in pediatric populations has not been extensively investigated. This study sought to assess the association between NAR and pulmonary cavitation in children and adolescents with active pulmonary tuberculosis (PTB), as well as to identify potential effect modifiers. A retrospective cohort study was undertaken involving 880 pediatric and adolescent patients (aged under 18 years) with microbiologically or clinically confirmed ATB, who were admitted to the Public Health Clinical Center of Chengdu from April 2022 to December 2024. Patients with HIV, comorbidities, or incomplete data were excluded from the study. The NAR was calculated using baseline complete blood count and serum albumin levels, and was subsequently log-transformed (lgNAR) for analytical purposes. Multivariable logistic regression models were employed to evaluate the association between lgNAR and pulmonary cavitation, with adjustments for age, gender, Bacillus Calmette-Guérin (BCG) vaccination status, tuberculin skin test (TST) results, history of exposure, previous tuberculosis history, and CD4 + and CD8 + T-cell counts. Subgroup analyses and restricted cubic spline (RCS) analyses were conducted to assess effect modification and dose–response relationships, respectively. Pulmonary cavitation was observed in 197 (22.4%) of the 880 patients studied. An elevated lgNAR was significantly correlated with an increased risk of cavitation; specifically, after comprehensive adjustment, each unit increase in lgNAR was associated with an 81% higher likelihood of cavitation (OR = 1.81; 95% CI 1.30–2.50; p < 0.001). When compared to patients in the lowest quartile (Q1), those in the highest NAR quartile (Q4) exhibited a significantly elevated risk of cavitation (OR = 1.88; 95% CI 1.17–3.00; p = 0.009), suggesting that higher lgNAR levels are associated with greater lung parenchymal damage. Subgroup analyses indicated a more pronounced association among treatment-naïve patients (OR = 2.67; 95% CI 1.82–3.91) and those with CD4 + T-cell counts ≤ 414 cells/μL (OR = 2.34), with a significant interaction based on treatment status (p for interaction < 0.001). A restricted cubic spline analysis confirmed a linear positive relationship between lgNAR and the odds of cavitation (overall p = 0.004; non-linearity p = 0.939). In summary, NAR appears to be a promising linear marker associated with lung cavitation in pediatric and adolescent PTB populations, reflecting inflammatory and nutritional status.