Is vitamin D (Vit D) a marker of severity of recurrent wheezing/asthma in infants?

Background : Vit D low serum levels have been linked to respiratory diseases including recurrent wheezing and asthma. We evaluate the impact of Vit D in recurrent wheezy (RW) children followed in the Pediatric Program for Prevention of Asthma (PIPA) in the city of Uruguaiana, Brazil Methods : Parents/caregivers of RW children (3 or > episodes;3-47 months old) referred to PIPA project had a written validate questionnaire filled in (International Study of Wheezing in Infants) and a blood sample collected for the determination of serum level of Vit D (Electro-chemiluminescence; normal = 30 ng/ml). According to Vit D they were split into: N1 (≥30ng/ml, N=124) and D2 (<30ng/ml, N=98). Results : Vit D mean serum level for N1 (42.7ng/ml) were significantly higher than D2 (22.9ng/ml). Except for current weight (12.5±4.5 x 11.6±3.5), the two groups were similar regarding: current age (months) (20.4±12.9 x 22.9±13.8), current height (cm) (83.6±16.7 x 81.2±12.3), age at first episode (months) (4.7±3.9 x 4.7±3.8), nightime awakenings/week (22.2% vs. 22.5%; Odds Ratio (OR): 1.01 (95%CI:0.61-1.69), emergency room visits (67.5% vs. 67.8%; OR:0.99 (95%CI:0,82-1.21), hospitalization for severe wheeze (18.8% vs. 19.0%, OR:0.98 (95%CI:0.56-1.74), physician-diagnosed asthma (28.2% vs. 38.2%, OR:0.74 (95%CI:0.50-1.09), hospitalization for pneumonia (17.2% vs. 12.5% ; OR:1.38 (95%CI:0.71-2.66) for N1 x D2, respectively. Conclusions : Although there was a trend toward more severity among patients with lower levels of Vit D this difference was not significant. Long-term studies are necessary for more reliable conclusions about the role of Vit D in these patients.