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 (R), central (R), and peripheral (R) airway resistance and reactance (X, 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 R (GLMM t-statistics:3.75, 95%CI:1.01,3.27, p-value<0.001*) and R (t-statistics:4.01, 95%CI:1.04,1.15, p-value<0.001*), but not with R 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 (R and R) 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.