Normative and Comparative CT-Derived Airway Indices in Asthmatics and Smokers in Rivers State, Nigeria: An Ambispective Study

Background: Quantitative computed tomography (QCT) provides objective morphometric measures of the airway and has increasingly been investigated as a non-invasive means of assessing and characterizing airway remodelling. However, locality-specific normative data are scarce in Nigeria. This study therefore established CT-derived airway indices among participants with normal airway findings and compared them with corresponding measurements in asthmatics and smoking adults in Rivers State, Nigeria. Methods: An ambispective cross-sectional study was carried out among 110 adults aged 18–75 years who underwent chest CT at a diagnostic centre in Rivers State, between March 2025 and March 2026. Participants comprised 63 adults with normal airway findings, 37 asthmatic adults, and 10 smokers. CT examinations were acquired at full inspiration and analyzed using an AI-assisted airway inspector on the Chest Imaging Platform. Airway wall thickness (AWT), airway lumen area (ALA) and wall area percentage (WA%) were extracted. Descriptive statistics, Shapiro–Wilk and Levene tests, one-way analysis of variance (ANOVA), Kruskal–Wallis testing with post-hoc comparisons, multiple linear regression, and an F-test were applied, with p < 0.05 considered statistically significant. Results: Mean AWT was 1.95 ± 0.30 mm among participants with normal airway findings, 2.79 ± 0.44 mm among asthmatics, and 3.45 ± 0.57 mm among smokers. ANOVA demonstrated a highly significant group difference (F = 103.30, p < 0.001). Tukey comparisons showed that AWT was greater in asthmatics than in participants with normal airway findings by 0.844 mm and greater in smokers than in participants with normal airway findings by 1.503 mm. The smoker–asthma difference was 0.659 mm; however, the non-parametric Dunn comparison did not demonstrate a statistically significant difference between these two groups (adjusted p = 0.121). Mean ALA was 20.0 ± 7.06 mm2 in participants with normal airway findings, 19.1 ± 9.64 mm2 in asthmatics, and 23.5 ± 7.79 mm2 in smokers, with no significant overall difference (p = 0.339). WA% was 67.1 ± 7.21%, 76.9 ± 8.84%, and 76.8 ± 9.11% for participants with normal airway findings, asthmatics and smokers, respectively, with a significant group difference (p < 0.001). Regression analysis showed that asthma and smoking were the principal predictors of AWT (R² = 0.671) and WA% (R² = 0.298), whereas age, gender, and weight were not significant predictors in the pooled models. Smokers had approximately 3.67 times the variance in AWT observed among participants with normal airway findings (F = 3.67, p = 0.001). Conclusion: This study provides preliminary locality-specific CT-derived airway reference values for participants with normal airway findings and demonstrates measurable airway remodelling in asthma and smoking. AWT and WA% appear more discriminating than ALA in this cohort. The findings support further multi-centre Nigerian studies recruiting a larger and gender-balanced sample size.

airway wall thickness; airway lumen area; wall area percentage; quantitative computed tomography; asthma; smoking; airway remodelling; Nigeria.

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