Effects of dexamethasone therapy on long-term pulmonary outcomes in VLBW infants.

Approximately 20% of very low birth weight (VLBW) infants develop chronic lung disease (CLD), a condition associated with long-term risk of respiratory morbidity and asthma during childhood and adolescence. Corticosteroids treatment, primarily dexamethasone (DEX), in the first few weeks of life might decrease the duration of ventilator dependence and the incidence of CLD, as indicated by some reviews. This effect may be due to a reduction in lung inflammation. However, experimental and clinical studies suggested that corticosteroids may impair alveolarization and determine long-term adverse effects, such as impaired growth and neurologic development. These findings led the American Academy of Pediatrics and the Canadian Paediatric Society to recommend against “routine use of systemic DEX for the prevention or treatment of chronic lung disease,” and for additional long-term follow-up of well-designed trials.
Studies on the long-term effects of postnatal corticosteroid treatment on pulmonary outcomes and growth in VLBW infants have shown inconsistent results. This can be, at least in part, attributed to some biases in design. Furthermore, surfactant was not routinely avaiable during these early trials. On these basis, an American group evaluated in a follow-up study the long-term effects of postnatal DEX exposure on pulmonary outcomes in a sample of school-aged children, included in a well designed trial, who had received surfactant.
In particular, 68 children aged 8 to 11, born with VLBW and included in a randomized trial, controlled with placebo, of postnatal DEX (initial dose 0.5 mg/kg/day) were considered in this analysis. Pulmonary function was assessed by spirometry and asthma status was obtained from a parent.
Results show that a significantly higher percentage of infants included in the placebo group had below-normal forced expiratory volume in 1 second (FEV1), compared with DEX group (68% vs 40%; P=0.03). Trends for lower forced vital capacity (FVC) and FEV1 values were reported in the placebo group. Moreover, 50% of infants in the placebo group versus 34% of those treated with DEX had below normal FEV1/FVC. Prevalence of asthma did not differ between groups. Statistical analysis suggested that the positive effects of DEX on pulmonary function were at least in part mediated by shortened exposure to mechanical ventilation.
Overall, results of this study suggest that postnatal DEX treatment in VLBW infants does not adversely affect pulmonary function at school age and in fact may impart some benefit, partially depending upon shorter mechanical ventilation. These results are consistent with the reported short-term benefits of DEX on pulmonary outcomes in the neonate, including decreased inflammation, duration of mechanical ventilation and supplemental oxygen dependence, and improved lung mechanics. Taken together, these factors may suggest that a brief course of DEX therapy could have some benefits in VLBW infants at risk of CLD. Moreover, this analysis can further underline the influence of neonatal illness on health at school age and the importance of surveillance to identify affected children.

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