Vitamin D status, growth, and pneumonia in a pediatric Andean population
Mokhtar, Rana Redha
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Vitamin D is known to benefit skeletal bone health and prevent rickets in children. Limited evidence exists to support a role of vitamin D in linear growth and stunting, especially in children at high risk for growth faltering, e.g. undernourished low socio-economic status children <5 years. Also, it is unclear if the immunomodulatory benefits of vitamin D impact childhood pneumonia. It is critical to determine whether vitamin D ameliorates stunting and pneumonia, as these conditions are responsible for a high burden of child mortality and morbidity. A secondary analysis of two studies in Ecuador was undertaken to determine the prevalence of vitamin D deficiency and the effect of vitamin D status on growth (height-for-age (HAZ) and weight-for-age (WAZ) z-scores) (n=516) and illness duration in children hospitalized for severe pneumonia (n=348). Serum 25-hydroxyvitamin D (25(OH)D) concentrations of children who participated in a community-based trial (ages 6-36 months) and hospital-based trial (ages 2-59 months) were determined at baseline. Overall, 18.6% of children had serum 25(OH)D levels <17 ng/ml (n=516), 62.2% were stunted (HAZ≤-2), and 65.5% were underweight (WAZ≤-1). Children with 25(OH)D concentrations <17 ng/ml had a higher risk of stunting (HAZ≤-2) than those with concentrations ≥17 ng/ml (ORadj: 2.8; 95%CI: 1.6, 4.7) in logistic regression models. Underweight (WAZ≤-1) children were twice as likely to have 25(OH)D concentrations <17 ng/ml than normal weight children (WAZ>-1) (ORadj: 2.0; 95%CI: 1.2,3.3). Vitamin D deficiency (≤20 ng/ml) did not affect pneumonia duration among hospitalized children in Cox proportional hazard models (HRadj: 1.2; 95% CI: 0.93,1.5). Younger children (2-12 months), underweight children (WAZ≤-2), and children with higher respiratory rates had a longer duration of illness (HRadj: 0.61; 95% CI: 0.43,0.86; HRadj: 0.78; 95% CI: 0.59,1.0; HRadj: 0.97; 95% CI: 0.96,0.99, respectively). Underweight Ecuadorian children are at increased risk for lower serum 25(OH)D concentrations. Low vitamin D status is associated with stunting among undernourished children but not with the duration of pneumonia illness. This indicates that vitamin D may be a modifiable risk factor for stunting, which, if validated in further research, can potentially impart beneficial effects on growth among stunted children in resource limited settings.