Relationships Between Impulse Oscillometry, Interleukins, Other Peripheral Blood Biomarkers and Asthma Control: A Pilot Study

Background: Impulse oscillometry (IOS) and type 2 inflammatory biomarkers are recognized methods for evaluating asthma, yet the direct relationship between small airway mechanics and systemic cytokines remains underexplored. This pilot study investigated the correlations between IOS parameters, peripheral blood biomarkers, and asthma control. Methods: We conducted a prospective, cross-sectional observational study on 41 adult patients with asthma. IOS parameters (R5Hz%, R20Hz%, ΔR5–20, X5Hz, Z5Hz%, Fres, AX), Asthma Control Test (ACT) scores, and peripheral blood biomarkers (eosinophils, total IgE, IL-4, IL-5, IL-8, IL-33) were assessed. Statistical associations were evaluated using Spearman’s rank correlation. Results: No significant correlations were found between IOS parameters and systemic inflammatory biomarkers (p > 0.05). The total ACT score did not correlate with either IOS or biomarker levels. Elevated IL-33 showed a nominally significant, uncorrected correlation with increased symptom burden (ACT Questions 2 and 4), and IOS indices reflecting small airway dysfunction (SAD)—ΔR5–20 (ρ = −0.391, p = 0.022), X5Hz (ρ = 0.380, p = 0.029), and AX (ρ = −0.370, p = 0.037)—showed nominally significant, uncorrected associations with asthma-induced limitations in daily activities (ACT Question 1). None of these associations remained statistically significant after Bonferroni correction for multiple comparisons. Conclusions: In this small pilot study, no significant associations were detected between IOS indices and peripheral blood biomarkers or total ACT scores, and none of the nominal item-level associations survived correction for multiple comparisons. The findings are hypothesis-generating only; larger, adequately powered, phenotype-stratified studies are needed.