Sex differences in the association between neck circumference and asthma

Abstract

Introduction: The association between obesity and asthma control/quality of life commonly relies on body mass index (BMI) as the anthropomorphic measure. Due to limitations of BMI and the existence of alternative measures, such as neck circumference (NC), we examined the association between NC and asthma control/quality of life, with particular attention to male-female differences.

Materials and methods: The AsthMaP-2 Project is an observational study of youth with physician-diagnosed asthma. NC was stratified according to age- and sex-specific cutoffs and associated with asthma control (via Asthma Control Test [ACT]) and quality of life (via Integrated Therapeutics Group [ITG]-Asthma Short Form).

Results: The mean ± SD age was 11.9 ± 3.6 years, and 53% were male (N = 116). The mean BMI percentile was at the 71 ± 28 percentile. Thirty-one participants (27%) met criteria for high NC. Males with high NC had significantly worse asthma control (P = 0.02) and lower quality of life than those with low NC. No similar association was found for females and the proportion of variability in ACT and ITG was best explained by BMI percentile. Conversely, for males, the proportion of variability in these scores explained by NC was larger than BMI percentile alone (Cohen's f(2) = 0.04-0.09, a small to medium effect size).

Discussion: Among male youth with asthma, combined use of NC and BMI percentile explained asthma control and quality of life better than BMI alone. Future studies of asthma should include measurement of NC and other anthropogenic measures of regional adiposity to clarify sex differences in asthma. Pediatr Pulmonol. 2016; 51:893-900. © 2016 Wiley Periodicals, Inc.

Trial registration: ClinicalTrials.gov NCT01647399.

Keywords: adiposity; body mass index; pediatric obesity; pediatrics.

Conflict of interest statement

None.

© 2016 Wiley Periodicals, Inc.

Figures

Fig. 1

Scatterplot of BMI percentile and percent difference between actual NC and NC cutoff. Mean ± SD ACT and ITG composite, functional, and daytime scores are shown for all four quadrants. The plot is notable for the worst control and quality of life (i.e., lowest ACT and ITG scores) in the upper right quadrant, where both BMI percentile and NC are above their respective cutoffs. BMI, body mass index; NC, neck circumference; ACT, asthma control test; ITG, integrated therapeutics group’s child asthma short form; ITGc, ITG composite; ITGf, ITG functional; ITGd, ITG daytime.