Abstract: Fourteen studies were included in this review. Only RCTs investigating dexamethasone were identified. Eight studies enrolling a total of 303 participants investigated the cumulative dosage administered; three studies contrasted a high versus a moderate and five studies a moderate versus a low cumulative dexamethasone dose. Analysis of the studies investigating a moderate dexamethasone dose versus a high-dosage regimen showed an increased risk of BPD (typical risk ratio (RR) 1.50, 95% confidence interval (CI) 1.01 to 2.22; typical risk difference (RD) 0.26, 95% CI 0.03 to 0.49; number needed to treat for an additional harmful outcome (NNTH) 4, 95% CI 1.9 to 23.3; I² = 0%, 2 studies, 55 infants) as well as an increased risk of abnormal neurodevelopmental outcome (typical RR 8.33, 95% CI 1.63 to 42.48; RD 0.30, 95% CI 0.14 to 0.46; NNTH 4, 95% CI 2.2 to 7.3; I² = 68%, 2 studies, 74 infants) when using a moderate cumulative-dosage regimen. The composite outcomes of death or BPD and death or abnormal neurodevelopmental outcome showed similar results although the former only reached borderline significance. There were no differences in outcomes between a moderate- and a low-dosage regimen. Four other studies enrolling 762 infants investigated early initiation of dexamethasone therapy versus a moderately early or delayed initiation and showed no significant differences in the primary outcomes. The two RCTs investigating a continuous versus a pulse dexamethasone regimen showed an increased risk of the combined outcome death or BPD when using the pulse therapy. Finally, two trials investigating a standard regimen versus a participant-individualized course of dexamethasone showed no difference in the primary outcome and long-term neurodevelopmental outcomes. The quality of evidence for all comparisons discussed above was assessed as low or very low, because the validity of all comparisons is hampered by small samples of randomized infants, heterogeneity in study population and design, non-protocolized use of ‘rescue’ corticosteroids and lack of long-term neurodevelopmental data in most studies. Despite the fact that some studies reported a modulating effect of treatment regimens in favor of higher-dosage regimens on the incidence of BPD and neurodevelopmental impairment, recommendations on the optimal type of corticosteroid, the optimal dosage, or the optimal timing of initiation for the prevention of BPD in preterm infants cannot be made based on current level of evidence. A well-designed large RCT is urgently needed to establish the optimal systemic postnatal corticosteroid dosage regimen.

Plain-language summary: Searching all electronic databases to 21 March 2016 revealed 14 studies investigating two or more different corticosteroid regimens in preterm infants. The investigated regimens differed in the used cumulative dose, timing of initiation and duration of therapy. Those studies comparing a high versus a lower-dosage regimen showed an increased risk of BPD and adverse neurodevelopmental outcome for infants receiving a lower cumulative dose. Those studies investigating an early versus later administration of steroids did not show any difference in outcome. Furthermore, pulse regimens showed inferior results for the outcome BPD compared with continuous treatment. An individualized dosage regimen showed no differences compared to the standard tapering course. Most of the studies had important methodological weaknesses, preventing any recommendations on the optimal corticosteroid dosage regimen for preterm infants at risk of BPD. More studies are urgently needed.