The influence of body mass index on airway resistance in children with sickle cell disease: A longitudinal study based on impulse oscillometry

Background: Impulse oscillometry (IOS) is an effective tool for assessing airway mechanics and diagnosing obstructive airway disease (OAD) in children with sickle cell disease (C-SCD). Obesity is known to be associated with OAD, and untreated OAD often leads to hypoxia-related complications in C-SCD. Considering the increasing prevalence of obesity in C-SCD, it is important to explore the influence of body mass index (BMI) on OAD in this disease population. Methods: A longitudinal retrospective chart review was conducted on 55 C-SCD (161 IOS observations) and 35 non-SCD asthmatic children (C-Asthma) (58 observations), primarily to investigate the association between BMI and airway resistance in C-SCD and C-Asthma. We conducted generalized linear mixed models (GLMM), adjusted for pharmacotherapies, to demonstrate the influence of BMI on total (R₅), central (R₂₀), and peripheral (R_5-20) airway resistance and reactance (X₅, resonant frequency (Fres)). We further compared age, BMI, and IOS indices between C-SCD and C-Asthma using the Mann-Whitney test. Results: Age and BMI were not statistically different between the two groups. In C-SCD, BMI was associated with R₅ (GLMM t-statistics:3.75, 95%CI:1.01,3.27, p-value<0.001*) and R₂₀ (t-statistics:4.01, 95%CI:1.04,1.15, p-value<0.001*), but not with R_5-20 or airway reactance. In asthmatics, BMI was not associated with IOS estimates except Fres (t-statistics: 3.93, 95%CI: −0.06, −0.02, p-value<0.001*). C-SCD demonstrated higher airway resistances (R₅ and R₂₀) and reactance (Fres) compared to C-Asthma (Mann-Whitney: p-values<0.05). Conclusion: BMI significantly influenced total and central airway resistance in C-SCD. While higher airway resistances reflected increased OAD in C-SCD than asthmatics, higher Fres perhaps indicated progressive pulmonary involvement in C-SCD.