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Vitamin D may impact corticosteroids' effect on BMA in boys with asthma

A dose-dependent relationship between oral corticosteroids and bone mineral accretion in boys with asthma may be significantly impacted by patients’ serum vitamin D levels, according to recent study results.

The study included 780 patients aged 5 to 12 years with mild-to-moderate asthma. All participants were involved with the Childhood Asthma Management Program and were randomly treated with budesonide, nedocromil or placebo with follow-up at 2 and 4 months after treatment initiation and then at 4-month intervals (mean follow-up, 4.3 years). Researchers collected the total number of inhaled corticosteroid and oral corticosteroid (OCS) doses, as well as serum 25-hydroxyvitamin D3 levels at baseline. Serial dual-energy X-ray absorptiometry scans also were performed on participants’ lumbar spines.

Across the entire cohort, the median vitamin D level was 34.3 ng/mL (IQR=26.9-45.6 ng/mL) and the median bone mineral accretion (BMA) was 0.041 g/cm²/y (IQR=0.026-0.066 g/cm²/y). The median number of OCS doses per year was 8.0 bursts among participants who received one or more courses per year, and a dose-dependent association was found between OCS and a decrease in BMA (P=.008).

Vitamin D levels at baseline affected the relationship between OCS doses and BMA in boys (P=.023). BMA decrease was associated with increased OCS doses only in boys with vitamin D deficiency after stratification by vitamin D levels (0.049 g/cm²/y; 95% CI, –0.008 to –0.002). Boys with insufficient vitamin D levels who received more than two OCS courses per year experienced BMA decreases at twice the rate of vitamin D-sufficient participants (–0.027 g/cm²/y compared with –0.014 g/cm²/y). No significant decrease in BMA coinciding with increased OCS use was established, with no impact from vitamin D level.

“This study not only supports an adverse effect on BMA associated with increasing use of OCSs in boys but also demonstrates that this negative effect is exacerbated by low serum vitamin D levels,” the researchers wrote. “Although further research is needed to confirm this finding and whether vitamin D supplementation can confer clinical benefits on future bone health, our data suggest that children, particularly boys, with asthma who have frequent exacerbations requiring OCS treatment might benefit from a vitamin D assessment.”