Asthma is a chronic disease of the airways triggered by underlying inflammatory processes. Although inflammation has been shown to negatively influence bone, little is known about the associations between asthma and bone in children. Therefore, we aimed to investigate the associations between asthma and levels of BMD and BMC in children assessed for the Vitamin D in Pregnancy study. .
From a sample of 195 children aged 10-12 years (median [interquartile range]:10.9 [10.7-11.4]), those in advanced Tanner stages (stages 3 and 4) and without asthma status allocation were excluded, leaving 157 eligible for analyses. BMD and BMC at L2-L4 spine and total body (less head) (TBLH) were ascertained by DXA (Lunar Prodigy). Using the International Study of Asthma and Allergies Survey, corticosteroid use was parent-reported and asthma status was defined as the combination of current wheezing and ‘ever had’ asthma. Linear regression techniques were used to determine the relationship between asthma status and height-adjusted BMD and BMC at the spine and TBLH. In the models, there was a sex*asthma interaction term, thus data were stratified by sex.
Twenty two (14.0%) reported having asthma (15 boys (68.2%) and 7 girls (31.8%)). Independent of height, a trend was observed in boys between asthma and spine BMD (β=-0.040, SE±0.024, p=0.1) and spine BMC (β=-1.606, SE±1.094, p=0.1). No associations were observed in girls. The pattern persisted after further adjustment for corticosteroids and a corticosteroid*asthma interaction was observed. The BMC differential was more pronounced among boys exposed to corticosteroids, but the BMD association was attenuated. No further associations were observed between asthma and TBLH for either sex.
Our findings suggest that asthma may play a role in bone mineralization in boys. Results should be interpreted with caution due to small numbers. Research using larger sample sizes is warranted and may further elucidate these relationships.