BMI Strongly Correlates with Airway Resistance in Children with Sickle Cell

While obesity is less common in pediatric sickle cell patients, BMI may impact airway resistance in this population.

A new study noted that BMI significantly correlated with airway resistance in patients with sickle cell disease (SCD). These findings were presented at the American Thoracic Society (ATS) International Conference.

“Obesity and its complications have recently become increasingly prevalent in [the] sickle cell disease population,” explained the investigative team, led by Pritish Mondal, MD, of Penn State Health. “Although obesity is unusual in children with SCD, a trend in the association between body mass index and airway resistance is still possible in this cohort.”

They explained how obesity can impact respiratory physiology, affecting lung compliance and strength of the respiratory pump. Further, airway resistance can also increase as a result of elevated transmural pressure across the chest wall and an enlarged circumference of the neck.

To explore the impacts of obesity on sickle cell populations, they used a retrospective chart review to identify and enroll 51 children with sickle cell disease. They also enrolled 35 age/race matched asthmatic children for their control group. Mondal and team then utilized impulse oscillometry (IOS) to measure upper (R20) and total airway resistance (R5) and airway reactance (X5 and resonant frequency).

The correlation between BMI and IOS were analyzed through a linear mixed-effect model.

There were equal numbers of males and females in each group. In the sickle cell cohort, HbSS was the predominant SCD genotype—followed by HbSC.

Notably, children with sickle cell disease had significantly lower BMI compared to the control group (18.17 versus 24.47).

“Linear mixed model analyses demonstrated that BMI had significant association with R5 (%predicted) (beta = 2.48; 95% CI, 1.46- 3.51; P<.001) and R20 (%pred) (beta = 2.26; 95% CI,1.49-3.02; P<.001) in [children with sickle cell disease],” they reported. “BMI was also significantly correlated with X5 (beta = -9.35; 95% CI, -3.20 to -15.50; P = .004) and FRES (%pred) (beta = 2.36; 95% CI, 1.13-3.58; P<.001) respectively, in the case group.

In the control group, BMI was found not to be associated with R5(%pred) (P = .14), R20 (%pred) (P = .18), and X5 (%pred) (P = .17). However, there was a negative correlation between BMI and FRES(%pred) (r = -0.34; P = .047).

There was also a strong correlation between R5(%pred) and FRES(%pred) in the sickle cell group (r = 0.75, P<0.001) and control group (r = 0.70; P<.001).

“Association between FRES and BMI further established BMI's influence on airway resistance since FRES is known to relate to airway resistance,” Mondal’s team wrote. “The respiratory system may be more influenced by BMI changes in [children with sickle cell disease] than controls, as pulmonary mechanics are affected in SCD by various conditions, including chronic inflammation, asthma, and increased pulmonary circulation.”

The study, “The Association Between BMI and Airways Resistance in Children with Sickle Cell Disease: A Longitudinal Study,” was presented at ATS 2021.