Statistical analyses of ordinal outcomes in randomised controlled trials: a scoping review

BACKGROUND

Randomised controlled trials (RCTs) aim to estimate the causal effect of one or more interventions relative to a control. One type of outcome that can be of interest in an RCT is an ordinal outcome, which is useful to answer clinical questions regarding complex and evolving patient states. The target parameter of interest for an ordinal outcome depends on the research question and the assumptions the analyst is willing to make. This review aimed to provide an overview of how ordinal outcomes have been used and analysed in RCTs.

METHODS

The review included RCTs with an ordinal primary or secondary outcome published between 2017 and 2022 in four highly ranked medical journals (the British Medical Journal, New England Journal of Medicine, The Lancet, and the Journal of the American Medical Association) identified through PubMed. Details regarding the study setting, design, the target parameter, and statistical methods used to analyse the ordinal outcome were extracted.

RESULTS

The search identified 309 studies, of which 144 were eligible for inclusion. The most used target parameter was an odds ratio, reported in 78 (54%) studies. The ordinal outcome was dichotomised for analysis in 47 ( 33 % ) studies, and the most common statistical model used to analyse the ordinal outcome on the full ordinal scale was the proportional odds model (64 [ 44 % ] studies). Notably, 86 (60%) studies did not explicitly check or describe the robustness of the assumptions for the statistical method(s) used.

CONCLUSIONS

The results of this review indicate that in RCTs that use an ordinal outcome, there is variation in the target parameter and the analytical approaches used, with many dichotomising the ordinal outcome. Few studies provided assurance regarding the appropriateness of the assumptions and methods used to analyse the ordinal outcome. More guidance is needed to improve the transparent reporting of the analysis of ordinal outcomes in future trials.

Non-invasive versus invasive respiratory support in preterm infants

Respiratory insufficiency is almost ubiquitous in infants born preterm, with its incidence increasing with lower gestational age. A wide range of respiratory support management strategies are available for these infants, separable into non-invasive and invasive forms of respiratory support. Here we review the history and evolution of respiratory care for the preterm infant and then examine evidence that has emerged to support a non-invasive approach to respiratory management where able. Continuous positive airway pressure (CPAP) is the non-invasive respiratory support mode currently with the most evidence for benefit. CPAP can be delivered safely and effectively and can commence in the delivery room. Particularly in early life, time spent on non-invasive respiratory support, avoiding intubation and mechanical ventilation, affords benefit for the preterm infant by virtue of a lessening of lung injury and hence a reduction in incidence of bronchopulmonary dysplasia. In recent years, enthusiasm for application of non-invasive support has been further bolstered by new techniques for administration of exogenous surfactant. Methods of less invasive surfactant delivery, in particular with a thin catheter, have allowed neonatologists to administer surfactant without resort to endotracheal intubation. The benefits of this approach appear to be sustained, even in those infants subsequently requiring mechanical ventilation. This cements the notion that any reduction in exposure to mechanical ventilation leads to alleviation of injury to the vulnerable preterm lung, with a long-lasting effect. Despite the clear advantages of non-invasive respiratory support, there will continue to be a role for intubation and mechanical ventilation in some preterm infants, particularly for those born <25 weeks' gestation. It is currently unclear what role early non-invasive support has in this special population, with more studies required.

Higher versus lower nasal continuous positive airway pressure for extubation of extremely preterm infants in Australia (ÉCLAT): a multicentre, randomised, superiority trial

BACKGROUND

Extremely preterm infants often require invasive mechanical ventilation, and clinicians aim to extubate these infants as soon as possible. However, extubation failure occurs in up to 60% of extremely preterm infants and is associated with increased mortality and morbidity. Nasal continuous positive airway pressure (nCPAP) is the most common post-extubation respiratory support, but there is no consensus on the optimal nCPAP level to safely avoid extubation failure in extremely preterm infants. We aimed to determine if higher nCPAP levels compared with standard nCPAP levels would decrease rates of extubation failure in extremely preterm infants within 7 days of their first extubation.

METHODS

In this multicentre, randomised, open-label controlled trial done at three tertiary perinatal centres in Australia, we assigned extremely preterm infants to extubation to either higher nCPAP (10 cmH2O) or standard nCPAP (7 cmH2O). Infants were eligible if they were born at less than 28 weeks' gestation, were receiving mechanical ventilation via an endotracheal tube, and were being extubated for the first time to nCPAP. Eligible infants must have received previous treatment with exogenous surfactant and caffeine. Infants were ineligible if they were planned to be extubated to a mode of respiratory support other than nCPAP, if they had a known major congenital anomaly that might affect breathing, or if ongoing intensive care was not being provided. Parents or guardians provided prospective, written, informed consent. Infants were maintained within an assigned nCPAP range for a minimum of 24 h after extubation (higher nCPAP group 9-11 cmH2O and standard nCPAP group 6-8 cmH2O). Randomisation was stratified by both gestation (22-25 completed weeks or 26-27 completed weeks) and recruiting centre. The primary outcome was extubation failure within 7 days and analysis was by intention to treat. This trial was prospectively registered with the Australian New Zealand Clinical Trials Registry, number ACTRN12618001638224.

FINDINGS

Between March 3, 2019, and July 31, 2022, 483 infants were born at less than 28 weeks and admitted to the recruiting centres. 92 infants were not eligible, 172 were not approached, 65 families declined to participate, and 15 consented but were not randomly assigned. 139 infants were enrolled and randomly assigned, 70 to the higher nCPAP group and 69 to the standard nCPAP group. One infant in the higher nCPAP group was excluded from the analysis because consent was withdrawn after randomisation. 104 (75%) of 138 mothers were White. The mean gestation was 25·7 weeks (SD 1·3) and the mean birthweight was 777 grams (201). 70 (51%) of 138 infants were female. Extubation failure occurred in 24 (35%) of 69 infants in the higher nCPAP group and in 39 (57%) of 69 infants in the standard nCPAP group (risk difference -21·7%, 95% CI -38·5% to -3·7%). There were no significant differences in rates of adverse events between groups during the primary outcome period. Three patients died (two in the higher nCPAP group and one in the standard nCPAP group), pneumothorax occurred in one patient from each group, spontaneous intestinal perforation in three patients (two in the higher nCPAP group and one in the standard nCPAP group) and there were no events of pulmonary interstitial emphysema.

INTERPRETATION

Extubation of extremely preterm infants to higher nCPAP significantly reduced extubation failure compared with extubation to standard nCPAP, without increasing rates of adverse effects. Future larger trials are essential to confirm these findings in terms of both efficacy and safety.

FUNDING

National Health and Medical Research Council Centre for Research Excellence in Newborn Medicine, number 1153176.

Surfactant as a drug carrier

Drug delivery using a surfactant vehicle has the potential to prevent systemic side effects by delivering therapeutic agents directly to the respiratory system. The inherent chemical properties of surfactant allows it to readily distribute throughout the respiratory system. Therapeutic agents delivered by surfactant can primarily confer additional benefits but have potential to improve surfactant function. It is critically important that additional agents do not interefere with the innate surface tension lowering function of surfactant. Systemic evaluation through benchtop, translational and human trials are required to translate this potential technique into clinical practice.

Intratracheal budesonide mixed with surfactant to increase survival free of bronchopulmonary dysplasia in extremely preterm infants: statistical analysis plan for the international, multicenter, randomized PLUSS trial

BACKGROUND

Bronchopulmonary dysplasia (BPD), an inflammatory-mediated chronic lung disease, is common in extremely preterm infants born before 28 weeks' gestation and is associated with an increased risk of adverse neurodevelopmental and respiratory outcomes in childhood. Effective and safe prophylactic therapies for BPD are urgently required. Systemic corticosteroids reduce rates of BPD in the short term but are associated with poorer neurodevelopmental outcomes if given to ventilated infants in the first week after birth. Intratracheal administration of corticosteroid admixed with exogenous surfactant could overcome these concerns by minimizing systemic sequelae. Several small, randomized trials have found intratracheal budesonide in a surfactant vehicle to be a promising therapy to increase survival free of BPD. The primary objective of the PLUSS trial is to determine whether intratracheal budesonide mixed with surfactant increases survival free of bronchopulmonary dysplasia (BPD) at 36 weeks' postmenstrual age (PMA) in extremely preterm infants born before 28 weeks' gestation.

METHODS

An international, multicenter, double-blinded, randomized trial of intratracheal budesonide (a corticosteroid) mixed with surfactant for extremely preterm infants to increase survival free of BPD at 36 weeks' postmenstrual age (PMA; primary outcome). Extremely preterm infants aged < 48 h after birth are eligible if (1) they are mechanically ventilated, or (2) they are receiving non-invasive respiratory support and there is a clinical decision to treat with surfactant. The intervention is budesonide (0.25 mg/kg) mixed with poractant alfa (200 mg/kg first intervention, 100 mg/kg if second intervention), administered intratracheally via an endotracheal tube or thin catheter. The comparator is poractant alfa alone (at the same doses). Secondary outcomes include the components of the primary outcome (death, BPD prior to or at 36 weeks' PMA), and potential systemic side effects of corticosteroids. Longer-term outcomes will be published separately, and include cost-effectiveness, early childhood health until 2 years of age, and neurodevelopmental outcomes at 2 years of age (corrected for prematurity).

STATISTICAL ANALYSIS PLAN

A sample size of 1038 infants (519 in each group) is required to provide 90% power to detect a relative increase in survival free of BPD of 20% (an absolute increase of 10%), from the anticipated event rate of 50% in the control arm to 60% in the intervention (budesonide) arm, alpha error 0.05. To allow for up to 2% of study withdrawals or losses to follow-up, PLUSS aimed to enroll a total of 1060 infants (530 in each arm). The binary primary outcome will be reported as the number and percentage of infants who were alive without BPD at 36 weeks' PMA for each randomization group. To estimate the difference in risk (with 95% CI), between the treatment and control arms, binary regression (a generalized linear multivariable model with an identity link function and binomial distribution) will be used. Along with the primary outcome, the individual components of the primary outcome (death, and physiological BPD at 36 weeks' PMA), will be reported by randomization group and, again, binary regression will be used to estimate the risk difference between the two treatment groups for survival and physiological BPD at 36 weeks' PMA.

Heterogeneity and Gaps in Reporting Primary Outcomes From Neonatal Trials

OBJECTIVES

Clear outcome reporting in clinical trials facilitates accurate interpretation and application of findings and improves evidence-informed decision-making. Standardized core outcomes for reporting neonatal trials have been developed, but little is known about how primary outcomes are reported in neonatal trials. Our aim was to identify strengths and weaknesses of primary outcome reporting in recent neonatal trials.

METHODS

Neonatal trials including ≥100 participants/arm published between 2015 and 2020 with at least 1 primary outcome from a neonatal core outcome set were eligible. Raters recruited from Cochrane Neonatal were trained to evaluate the trials' primary outcome reporting completeness using relevant items from Consolidated Standards of Reporting Trials 2010 and Consolidated Standards of Reporting Trials-Outcomes 2022 pertaining to the reporting of the definition, selection, measurement, analysis, and interpretation of primary trial outcomes. All trial reports were assessed by 3 raters. Assessments and discrepancies between raters were analyzed.

RESULTS

Outcome-reporting evaluations were completed for 36 included neonatal trials by 39 raters. Levels of outcome reporting completeness were highly variable. All trials fully reported the primary outcome measurement domain, statistical methods used to compare treatment groups, and participant flow. Yet, only 28% of trials fully reported on minimal important difference, 24% on outcome data missingness, 66% on blinding of the outcome assessor, and 42% on handling of outcome multiplicity.

CONCLUSIONS

Primary outcome reporting in neonatal trials often lacks key information needed for interpretability of results, knowledge synthesis, and evidence-informed decision-making in neonatology. Use of existing outcome-reporting guidelines by trialists, journals, and peer reviewers will enhance transparent reporting of neonatal trials.

Strengthening Reporting of Neonatal Trials

BACKGROUND AND OBJECTIVES

There is variability in the selection and reporting of outcomes in neonatal trials with key information frequently omitted. This can impact applicability of trial findings to clinicians, families, and caregivers, and impair evidence synthesis. The Neonatal Core Outcomes Set describes outcomes agreed as clinically important that should be assessed in all neonatal trials, and Consolidated Standards of Reporting Trials (CONSORT)-Outcomes 2022 is a new, harmonized, evidence-based reporting guideline for trial outcomes. We reviewed published trials using CONSORT-Outcomes 2022 guidance to identify exemplars of neonatal core outcome reporting to strengthen description of outcomes in future trial publications.

METHODS

Neonatal trials including >100 participants per arm published between 2015 to 2020 with a primary outcome included in the Neonatal Core Outcome Set were identified. Primary outcome reporting was reviewed using CONSORT 2010 and CONSORT-Outcomes 2022 guidelines by assessors recruited from Cochrane Neonatal. Examples of clear and complete outcome reporting were identified with verbatim text extracted from trial reports.

RESULTS

Thirty-six trials were reviewed by 39 assessors. Examples of good reporting for CONSORT 2010 and CONSORT-Outcomes 2022 criteria were identified and subdivided into 3 outcome categories: "survival," "short-term neonatal complications," and "long-term developmental outcomes" depending on the core outcomes to which they relate. These examples are presented to strengthen future research reporting.

CONCLUSIONS

We have identified examples of good trial outcome reporting. These illustrate how important neonatal outcomes should be reported to meet the CONSORT 2010 and CONSORT-Outcomes 2022 guidelines. Emulating these examples will improve the transmission of information relating to outcomes and reduce associated research waste.

Estimating Preterm Lung Volume: A Comparison of Lung Ultrasound, Chest Radiography, and Oxygenation

OBJECTIVE

To determine the relationship between lung ultrasound (LUS) examination, chest radiograph (CXR), and radiographic and clinical evaluations in the assessment of lung volume in preterm infants.

STUDY DESIGN

In this prospective cohort study LUS was performed before CXR on 70 preterm infants and graded using (1) a LUS score, (2) an atelectasis score, and (3) measurement of atelectasis depth. Radiographic diaphragm position and radio-opacification were used to determine global and regional radiographic atelectasis. The relationship between LUS, CXR, and oxygenation was assessed using receiver operator characteristic and correlation analysis.

RESULTS

LUS scores, atelectasis scores, and atelectasis depth did not correspond with radiographic global atelectasis (area under receiver operator characteristics curves, 0.54 [95% CI, 0.36-0.71], 0.49 [95% CI, 0.34-0.64], and 0.47 [95% CI, 0.31-0.64], respectively). Radiographic atelectasis of the right upper, right lower, left upper, and left lower quadrants was predicted by LUS scores (0.75 [95% CI, 0.59-0.92], 0.75 [95% CI, 0.62-0.89], 0.69 [95% CI, 0.56-0.82], and 0.63 [95% CI, 0.508-0.751]) and atelectasis depth (0.66 [95% CI, 0.54-0.78], 0.65 [95% CI, 0.53-0.77], 0.63 [95% CI, 0.50-0.76], and 0.56 [95% CI, 0.44-0.70]). LUS findings were moderately correlated with oxygen saturation index (ρ = 0.52 [95% CI, 0.30-0.70]) and saturation to fraction of inspired oxygen ratio (ρ = -0.63 [95% CI, -0.76 to -0.46]). The correlation between radiographic diaphragm position, the oxygenation saturation index, and peripheral oxygen saturation to fraction of inspired oxygen ratio was very weak (ρ = 0.36 [95% CI, 0.11-0.59] and ρ = -0.32 [95% CI, -0.53 to -0.07], respectively).

CONCLUSIONS

LUS assessment of lung volume does not correspond with radiographic diaphragm position preterm infants. However, LUS predicted radiographic regional atelectasis and correlated with oxygenation. The relationship between radiographic diaphragm position and oxygenation was very weak. Although LUS may not replace all radiographic measures of lung volume, LUS more accurately reflects respiratory status in preterm infants.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry: ACTRN12621001119886.

Postnatal corticosteroids and developmental outcomes in extremely preterm or extremely low birth weight infants: The Victorian Infant Collaborative Study 2016-17 cohort

AIM

Systemic postnatal corticosteroids are used to treat or prevent bronchopulmonary dysplasia (BPD) in extremely preterm (EP) or extremely low birth weight (ELBW) infants but are associated with long-term harm. We aimed to assess the relationship between cumulative postnatal corticosteroid dose and neurodevelopmental outcomes.

METHODS

Longitudinal cohort study of all EP/ELBW livebirths in Victoria, Australia 2016-2017. Perinatal data were collected prospectively. Neurodevelopmental assessment was performed at 2 years' corrected age. Linear and logistic regression were used to determine relationships between cumulative corticosteroid dose and neurodevelopment, adjusted for gestational age, birth weight, sex and major intraventricular haemorrhage.

RESULTS

Seventy-six EP/ELBW infants received postnatal corticosteroids to treat or prevent BPD, 62/65 survivors were seen at 2 years. Median (IQR) cumulative postnatal corticosteroid dose was 1.36 (0.92-3.45) mg/kg dexamethasone equivalent. Higher cumulative corticosteroid dose was associated with increased odds of cerebral palsy, adjusted OR (95% CI) 1.47 (1.04, 2.07). Higher cumulative corticosteroid dose was also associated with lower cognitive and motor developmental scores, however, this weakened after adjustment for confounding variables: cognitive composite score adjusted coefficient (95% CI) -1.3 (-2.7, 0.1) and motor composite score adjusted coefficient (95% CI) -1.3 (-2.8, 0.2).

CONCLUSION

Higher cumulative postnatal corticosteroid dose in EP/ELBW infants is associated with increased odds of cerebral palsy at 2 years' corrected age. Adequately powered studies are needed to assess the independent effects of cumulative steroid dose on neurodevelopmental outcomes.

Intratracheal budesonide mixed with surfactant to increase survival free of bronchopulmonary dysplasia in extremely preterm infants: study protocol for the international, multicenter, randomized PLUSS trial

BACKGROUND

Bronchopulmonary dysplasia (BPD), an inflammatory-mediated chronic lung disease, is common in extremely preterm infants born before 28 weeks' gestation and is associated with an increased risk of adverse neurodevelopmental and respiratory outcomes in childhood. Effective and safe prophylactic therapies for BPD are urgently required. Systemic corticosteroids reduce rates of BPD in the short-term but are associated with poorer neurodevelopmental outcomes if given to ventilated infants in the first week after birth. Intratracheal administration of corticosteroid admixed with exogenous surfactant could overcome these concerns by minimizing systemic sequelae. Several small, randomized trials have found intratracheal budesonide in a surfactant vehicle to be a promising therapy to increase survival free of BPD.

METHODS

An international, multicenter, double-blinded, randomized trial of intratracheal budesonide (a corticosteroid) mixed with surfactant for extremely preterm infants to increase survival free of BPD at 36 weeks' postmenstrual age (PMA; primary outcome). Extremely preterm infants aged < 48 h after birth are eligible if: (1) they are mechanically ventilated, or (2) they are receiving non-invasive respiratory support and there is a clinical decision to treat with surfactant. The intervention is budesonide (0.25 mg/kg) mixed with poractant alfa (200 mg/kg first intervention, 100 mg/kg if second intervention), administered intratracheally via an endotracheal tube or thin catheter. The comparator is poractant alfa alone (at the same doses). Secondary outcomes include the components of the primary outcome (death, BPD prior to or at 36 weeks' PMA), potential systemic side effects of corticosteroids, cost-effectiveness, early childhood health until 2 years of age, and neurodevelopmental outcomes at 2 years of age (corrected for prematurity).

DISCUSSION

Combining budesonide with surfactant for intratracheal administration is a simple intervention that may reduce BPD in extremely preterm infants and translate into health benefits in later childhood. The PLUSS trial is powered for the primary outcome and will address gaps in the evidence due to its pragmatic and inclusive design, targeting all extremely preterm infants regardless of their initial mode of respiratory support. Should intratracheal budesonide mixed with surfactant increase survival free of BPD, without severe adverse effects, this readily available intervention could be introduced immediately into clinical practice.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ( https://www.anzctr.org.au ), ACTRN12617000322336. First registered on 28th February 2017.

Nasal high flow therapy for primary respiratory support in preterm infants

BACKGROUND

Nasal high flow (nHF) therapy provides heated, humidified air and oxygen via two small nasal prongs, at gas flows of more than 1 litre/minute (L/min), typically 2 L/min to 8 L/min. nHF is commonly used for non-invasive respiratory support in preterm neonates. It may be used in this population for primary respiratory support (avoiding, or prior to the use of mechanical ventilation via an endotracheal tube) for prophylaxis or treatment of respiratory distress syndrome (RDS). This is an update of a review first published in 2011 and updated in 2016.

OBJECTIVES

To evaluate the benefits and harms of nHF for primary respiratory support in preterm infants compared to other forms of non-invasive respiratory support.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date March 2022.

SELECTION CRITERIA

We included randomised or quasi-randomised trials comparing nHF with other forms of non-invasive respiratory support for preterm infants born less than 37 weeks' gestation with respiratory distress soon after birth.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane Neonatal methods. Our primary outcomes were 1. death (before hospital discharge) or bronchopulmonary dysplasia (BPD), 2. death (before hospital discharge), 3. BPD, 4. treatment failure within 72 hours of trial entry and 5. mechanical ventilation via an endotracheal tube within 72 hours of trial entry. Our secondary outcomes were 6. respiratory support, 7. complications and 8. neurosensory outcomes. We used GRADE to assess the certainty of evidence.

MAIN RESULTS

We included 13 studies (2540 infants) in this updated review. There are nine studies awaiting classification and 13 ongoing studies. The included studies differed in the comparator treatment (continuous positive airway pressure (CPAP) or nasal intermittent positive pressure ventilation (NIPPV)), the devices for delivering nHF and the gas flows used. Some studies allowed the use of 'rescue' CPAP in the event of nHF treatment failure, prior to any mechanical ventilation, and some allowed surfactant administration via the INSURE (INtubation, SURfactant, Extubation) technique without this being deemed treatment failure. The studies included very few extremely preterm infants less than 28 weeks' gestation. Several studies had unclear or high risk of bias in one or more domains. Nasal high flow compared with continuous positive airway pressure for primary respiratory support in preterm infants Eleven studies compared nHF with CPAP for primary respiratory support in preterm infants. When compared with CPAP, nHF may result in little to no difference in the combined outcome of death or BPD (risk ratio (RR) 1.09, 95% confidence interval (CI) 0.74 to 1.60; risk difference (RD) 0, 95% CI -0.02 to 0.02; 7 studies, 1830 infants; low-certainty evidence). Compared with CPAP, nHF may result in little to no difference in the risk of death (RR 0.78, 95% CI 0.44 to 1.39; 9 studies, 2009 infants; low-certainty evidence), or BPD (RR 1.14, 95% CI 0.74 to 1.76; 8 studies, 1917 infants; low-certainty evidence). nHF likely results in an increase in treatment failure within 72 hours of trial entry (RR 1.70, 95% CI 1.41 to 2.06; RD 0.09, 95% CI 0.06 to 0.12; number needed to treat for an additional harmful outcome (NNTH) 11, 95% CI 8 to 17; 9 studies, 2042 infants; moderate-certainty evidence). However, nHF likely does not increase the rate of mechanical ventilation (RR 1.04, 95% CI 0.82 to 1.31; 9 studies, 2042 infants; moderate-certainty evidence). nHF likely results in a reduction in pneumothorax (RR 0.66, 95% CI 0.40 to 1.08; 10 studies, 2094 infants; moderate-certainty evidence) and nasal trauma (RR 0.49, 95% CI 0.36 to 0.68; RD -0.06, 95% CI -0.09 to -0.04; 7 studies, 1595 infants; moderate-certainty evidence). Nasal high flow compared with nasal intermittent positive pressure ventilation for primary respiratory support in preterm infants Four studies compared nHF with NIPPV for primary respiratory support in preterm infants. When compared with NIPPV, nHF may result in little to no difference in the combined outcome of death or BPD, but the evidence is very uncertain (RR 0.64, 95% CI 0.30 to 1.37; RD -0.05, 95% CI -0.14 to 0.04; 2 studies, 182 infants; very low-certainty evidence). nHF may result in little to no difference in the risk of death (RR 0.78, 95% CI 0.36 to 1.69; RD -0.02, 95% CI -0.10 to 0.05; 3 studies, 254 infants; low-certainty evidence). nHF likely results in little to no difference in the incidence of treatment failure within 72 hours of trial entry compared with NIPPV (RR 1.27, 95% CI 0.90 to 1.79; 4 studies, 343 infants; moderate-certainty evidence), or mechanical ventilation within 72 hours of trial entry (RR 0.91, 95% CI 0.62 to 1.33; 4 studies, 343 infants; moderate-certainty evidence). nHF likely results in a reduction in nasal trauma, compared with NIPPV (RR 0.21, 95% CI 0.09 to 0.47; RD -0.17, 95% CI -0.24 to -0.10; 3 studies, 272 infants; moderate-certainty evidence). nHF likely results in little to no difference in the rate of pneumothorax (RR 0.78, 95% CI 0.40 to 1.53; 4 studies, 344 infants; moderate-certainty evidence). Nasal high flow compared with ambient oxygen We found no studies examining this comparison. Nasal high flow compared with low flow nasal cannulae We found no studies examining this comparison.

AUTHORS' CONCLUSIONS

The use of nHF for primary respiratory support in preterm infants of 28 weeks' gestation or greater may result in little to no difference in death or BPD, compared with CPAP or NIPPV. nHF likely results in an increase in treatment failure within 72 hours of trial entry compared with CPAP; however, it likely does not increase the rate of mechanical ventilation. Compared with CPAP, nHF use likely results in less nasal trauma and likely a reduction in pneumothorax. As few extremely preterm infants less than 28 weeks' gestation were enrolled in the included trials, evidence is lacking for the use of nHF for primary respiratory support in this population.

Statistical analyses of ordinal outcomes in randomised controlled trials: protocol for a scoping review

INTRODUCTION

Randomised controlled trials (RCTs) aim to assess the effect of one (or more) unproven health interventions relative to other reference interventions. RCTs sometimes use an ordinal outcome, which is an endpoint that comprises of multiple, monotonically ordered categories that are not necessarily separated by a quantifiable distance. Ordinal outcomes are appealing in clinical settings as specific disease states can represent meaningful categories that may be of clinical importance to researchers. Ordinal outcomes can also retain information and increase statistical power compared to dichotomised outcomes and can allow multiple clinical outcomes to be comprised in a single endpoint. Target parameters for ordinal outcomes in RCTs may vary depending on the nature of the research question, the modelling assumptions and the expertise of the data analyst. The aim of this scoping review is to systematically describe the use of ordinal outcomes in contemporary RCTs. Specifically, we aim to: [Formula: see text] Identify which target parameters are of interest in trials that use an ordinal outcome, and whether these parameters are explicitly defined. [Formula: see text] Describe how ordinal outcomes are analysed in RCTs to estimate a treatment effect. [Formula: see text] Describe whether RCTs that use an ordinal outcome adequately report key methodological aspects specific to the analysis of the ordinal outcome. Results from this review will outline the current state of practice of the use of ordinal outcomes in RCTs. Ways to improve the analysis and reporting of ordinal outcomes in RCTs will be discussed.

METHODS AND ANALYSIS

We will review RCTs that are published in the top four medical journals (British Medical Journal, New England Journal of Medicine, The Lancet and the Journal of the American Medical Association) between 1 January 2012 and 31 July 2022 that use an ordinal outcome as either a primary or a secondary outcome. The review will identify articles through a PubMed-specific search strategy. Our review will adhere to guidelines for scoping reviews as described in the PRISMA-ScR checklist. The study characteristics and details of the study design and analysis, including the target parameter(s) and statistical methods used to analyse the ordinal outcome, will be extracted from eligible studies. The screening, review and data extraction will be conducted using Covidence, a web-based tool for managing systematic reviews. The data will be summarised using descriptive statistics.

Lung ultrasound of the dependent lung detects real-time changes in lung volume in the preterm lamb

BACKGROUND

Effective lung protective ventilation requires reliable, real-time estimation of lung volume at the bedside. Neonatal clinicians lack a readily available imaging tool for this purpose.

OBJECTIVE

To determine the ability of lung ultrasound (LUS) of the dependent region to detect real-time changes in lung volume, identify opening and closing pressures of the lung, and detect pulmonary hysteresis.

METHODS

LUS was performed on preterm lambs (n=20) during in vivo mapping of the pressure-volume relationship of the respiratory system using the super-syringe method. Electrical impedance tomography was used to derive regional lung volumes. Images were blindly graded using an expanded scoring system. The scores were compared with total and regional lung volumes, and differences in LUS scores between pressure increments were calculated.

RESULTS

Changes in LUS scores correlated moderately with changes in total lung volume (r=0.56, 95% CI 0.47-0.64, p<0.0001) and fairly with right whole (r=0.41, CI 0.30-0.51, p<0.0001), ventral (r=0.39, CI 0.28-0.49, p<0.0001), central (r=0.41, CI 0.31-0.52, p<0.0001) and dorsal (r=0.38, CI 0.27-0.49, p<0.0001) regional lung volumes. The pressure-volume relationship of the lung exhibited hysteresis in all lambs. LUS was able to detect hysteresis in 17 (85%) lambs. The greatest changes in LUS scores occurred at the opening and closing pressures.

CONCLUSION

LUS was able to detect large changes in total and regional lung volume in real time and correctly identified opening and closing pressures but lacked the precision to detect small changes in lung volume. Further work is needed to improve precision prior to translation to clinical practice.

"Harry Potter and the Multitudinous Maladies": a retrospective population-based observational study of morbidity and mortality among witches and wizards

OBJECTIVES

To describe the prevalence of maladies and deaths among witches and wizards in the Harry Potter world, their causes, and associated therapies.

DESIGN

Retrospective population-based observational study (report analysis) undertaken 10 February - 19 March 2022.

SETTING

All locations described in the Harry Potter books, predominantly Hogwarts School of Witchcraft and Wizardry, but also selected locations, including Privet Drive No 4, Diagon Alley, the Ministry of Magic, and The Burrow.

PARTICIPANTS

All witches and wizards mentioned at least once in any of the seven Harry Potter books.

MAIN OUTCOME MEASURES

Overall numbers of maladies and deaths. Secondary outcomes were changes in morbidity and mortality over time, causes of morbidity and mortality, and treatments.

RESULTS

A total of 603 wizards or witches named in the Potter books experienced 1541 maladies and injuries (1410 non-fatal) and 131 deaths. Overall morbidity incidence was 471 events per 1000 individuals, and mortality, after adjustment for Lord Voldemort's multi-mortality, was 20.6%. The most frequent causes of morbidity were traumatic injuries during duels or fights (553 cases, 39.2%), magical objects, potions, plants, or creatures (345, 24.5%), and non-combative trauma (221, 15.7%). Most deaths were related to wizarding duels (101 of 131, 77.1%). Treatments were rarely described; the most frequent were jinxes (274, 19.4%) and potions (136, 9.6%). Hospital stays were shorter than a week for almost all non-fatal maladies (1397 of 1410, 99.1%).

CONCLUSIONS

Morbidity and, in particular, mortality were very high and predominantly caused by magical means. Further investigation into the safety at Hogwarts School of Witchcraft and Wizardry is warranted. The few treatments used had high success rates; rapid recovery was the rule, and hospital stays generally brief. Efforts should be undertaken to identify the magical therapies and interventions used and to introduce these novel remedies into Muggle medicine.

Trends in the use of non-invasive respiratory support for term infants in tertiary neonatal units in Australia and New Zealand

OBJECTIVE

To determine whether the use of non-invasive respiratory support, such as continuous positive airway pressure and nasal high flow, to treat term infants in Australian and New Zealand tertiary neonatal intensive care units (NICUs) has changed over time, and if so, whether there are parallel changes in short-term respiratory morbidities.

DESIGN

Retrospective database review of patient-level data from the Australian and New Zealand Neonatal Network (ANZNN) from 2010 to 2018. Denominator data on the number of term inborn livebirths in each facility was only available as annual totals.

PATIENTS AND SETTING

Term, inborn infants cared for in NICUs within the ANZNN.

MAIN OUTCOME MEASURES

The primary outcome was the annual change in hospital-specific rates of non-invasive respiratory support per 1000 inborn livebirths, expressed as a percentage change. Secondary outcomes were the change in rates of mechanical ventilation, pneumothorax requiring drainage, exogenous surfactant treatment and death before hospital discharge.

RESULTS

A total of 14 656 term infants from 21 NICUs were included from 2010 to 2018, of whom 12 719 received non-invasive respiratory support. Non-invasive respiratory support use increased on average by 8.7% per year (95% CI: 7.9% to 9.4% per year); the number of term infants receiving non-invasive respiratory support almost doubled from 980 in 2010 (10.8/1000 livebirths) to 1913 in 2018 (20.8/1000). There was no change over time in rate of mechanical ventilation or death. The rate of pneumothorax requiring drainage increased over time, as did surfactant treatment.

CONCLUSIONS

Non-invasive respiratory support use to treat term infants cared for in NICUs within the ANZNN is increasing over time. Clinicians should be diligent in selecting infants most likely to benefit from treatment with non-invasive respiratory support in this relatively low-risk population of term newborn infants. Analysis of patient-level data by individual NICUs is recommended to control for potential confounding due to changes in population over time.

Quantitative lung ultrasound detects dynamic changes in lung recruitment in the preterm lamb

BACKGROUND

Lung ultrasound (LUS) may not detect small, dynamic changes in lung volume. Mean greyscale measurement using computer-assisted image analysis (Q-LUS_MGV) may improve the precision of these measurements.

METHODS

Preterm lambs (n = 40) underwent LUS of the dependent or non-dependent lung during static pressure-volume curve mapping. Total and regional lung volumes were determined using the super-syringe technique and electrical impedance tomography. Q-LUS_MGV and gold standard measurements of lung volume were compared in 520 images.

RESULTS

Dependent Q-LUS_MGV moderately correlated with total lung volume (rho = 0.60, 95% CI 0.51-0.67) and fairly with right whole (rho = 0.39, 0.27-0.49), central (rho = 0.38, 0.27-0.48), ventral (rho = 0.41, 0.31-0.51) and dorsal regional lung volumes (rho = 0.32, 0.21-0.43). Non-dependent Q-LUS_MGV moderately correlated with total lung volume (rho = 0.57, 0.48-0.65) and fairly with right whole (rho = 0.43, 0.32-0.52), central (rho = 0.46, 0.35-0.55), ventral (rho = 0.36, 0.25-0.47) and dorsal lung volumes (rho = 0.36, 0.25-0.47). All correlation coefficients were statistically significant. Distinct inflation and deflation limbs, and sonographic pulmonary hysteresis occurred in 95% of lambs. The greatest changes in Q-LUS_MGV occurred at the opening and closing pressures.

CONCLUSION

Q-LUS_MGV detected changes in total and regional lung volume and offers objective quantification of LUS images, and may improve bedside discrimination of real-time changes in lung volume.

IMPACT

Lung ultrasound (LUS) offers continuous, radiation-free imaging that may play a role in assessing lung recruitment but may not detect small changes in lung volume. Mean greyscale image analysis using computer-assisted quantitative LUS (Q-LUS_MGV) moderately correlated with changes in total and regional lung volume. Q-LUS_MGV identified opening and closing pressure and pulmonary hysteresis in 95% of lambs. Computer-assisted image analysis may enhance LUS estimation of lung recruitment at the bedside. Future research should focus on improving precision prior to clinical translation.

Nasal High-Flow Therapy during Neonatal Endotracheal Intubation

BACKGROUND

Neonatal endotracheal intubation often involves more than one attempt, and oxygen desaturation is common. It is unclear whether nasal high-flow therapy, which extends the time to desaturation during elective intubation in children and adults receiving general anesthesia, can improve the likelihood of successful neonatal intubation on the first attempt.

METHODS

We performed a randomized, controlled trial to compare nasal high-flow therapy with standard care (no nasal high-flow therapy or supplemental oxygen) in neonates undergoing oral endotracheal intubation at two Australian tertiary neonatal intensive care units. Randomization of intubations to the high-flow group or the standard-care group was stratified according to trial center, the use of premedication for intubation (yes or no), and postmenstrual age of the infant (≤28 or >28 weeks). The primary outcome was successful intubation on the first attempt without physiological instability (defined as an absolute decrease in the peripheral oxygen saturation of >20% from the preintubation baseline level or bradycardia with a heart rate of <100 beats per minute) in the infant.

RESULTS

The primary intention-to-treat analysis included the outcomes of 251 intubations in 202 infants; 124 intubations were assigned to the high-flow group and 127 to the standard-care group. The infants had a median postmenstrual age of 27.9 weeks and a median weight of 920 g at the time of intubation. A successful intubation on the first attempt without physiological instability was achieved in 62 of 124 intubations (50.0%) in the high-flow group and in 40 of 127 intubations (31.5%) in the standard-care group (adjusted risk difference, 17.6 percentage points; 95% confidence interval [CI], 6.0 to 29.2), for a number needed to treat of 6 (95% CI, 4 to 17) for 1 infant to benefit. Successful intubation on the first attempt regardless of physiological stability was accomplished in 68.5% of the intubations in the high-flow group and in 54.3% of the intubations in the standard-care group (adjusted risk difference, 15.8 percentage points; 95% CI, 4.3 to 27.3).

CONCLUSIONS

Among infants undergoing endotracheal intubation at two Australian tertiary neonatal intensive care units, nasal high-flow therapy during the procedure improved the likelihood of successful intubation on the first attempt without physiological instability in the infant. (Funded by the National Health and Medical Research Council; Australian New Zealand Clinical Trials Registry number, ACTRN12618001498280.).

Rapid centralised randomisation in emergency setting trials using a smartphone

Randomised trials in emergency settings must quickly confirm eligibility and allocate participants to an intervention group without delaying treatment. We report rapid randomisation during two neonatal resuscitation trials using the non-commercial REDCap platform accessed via smartphone. This simple, reliable method has wide applicability for trials in emergency settings. What is Known: • Randomised trials in emergency settings need to rapidly allocate participants to an intervention group. • This process should not delay treatment. What is New: • This non-commercial, smartphone-accessible application enabled rapid, accurate randomisation at the bedside. • This has broad applicability for emergency setting trials.

Impact of early respiratory care for extremely preterm infants

Despite advances in neonatal intensive care, more than half of surviving infants born extremely preterm (EP; < 28 weeks' gestation) develop bronchopulmonary dysplasia (BPD). Prevention of BPD is critical because of its associated mortality and morbidity, including adverse neurodevelopmental outcomes and respiratory health in later childhood and beyond. The respiratory care of EP infants begins before birth, then continues in the delivery room and throughout the primary hospitalization. This chapter will review the evidence for interventions after birth that might improve outcomes for infants born EP, including the timing of umbilical cord clamping, strategies to avoid or minimize exposure to mechanical ventilation, modes of mechanical ventilation and non-invasive respiratory support, oxygen saturation targets, postnatal corticosteroids and other adjunct therapies.

Late (≥ 7 days) systemic postnatal corticosteroids for prevention of bronchopulmonary dysplasia in preterm infants

BACKGROUND

Many infants born preterm develop bronchopulmonary dysplasia (BPD), with lung inflammation playing a role. Corticosteroids have powerful anti-inflammatory effects and have been used to treat individuals with established BPD. However, it is unclear whether any beneficial effects outweigh the adverse effects of these drugs.

OBJECTIVES

To examine the relative benefits and adverse effects of late (starting at seven or more days after birth) systemic postnatal corticosteroid treatment for preterm infants with evolving or established BPD.

SEARCH METHODS

We ran an updated search on 25 September 2020 of the following databases: CENTRAL via CRS Web and MEDLINE via OVID. We also searched clinical trials databases and reference lists of retrieved articles for randomised controlled trials (RCTs). We did not include quasi-RCTs.

SELECTION CRITERIA

We selected for inclusion in this review RCTs comparing systemic (intravenous or oral) postnatal corticosteroid treatment versus placebo or no treatment started at seven or more days after birth for preterm infants with evolving or established BPD. We did not include trials of inhaled corticosteroids.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. We extracted and analysed data regarding clinical outcomes that included mortality, BPD, and cerebral palsy. We used the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

Use of the GRADE approach revealed that the certainty of evidence was high for most of the major outcomes considered, except for BPD at 36 weeks for all studies combined and for the dexamethasone subgroup, which were downgraded one level to moderate because of evidence of publication bias, and for the combined outcome of mortality or BPD at 36 weeks for all studies combined and for the dexamethasone subgroup, which were downgraded one level to moderate because of evidence of substantial heterogeneity. We included 23 RCTs (1817 infants); 21 RCTS (1382 infants) involved dexamethasone (one also included hydrocortisone) and two RCTs (435 infants) involved hydrocortisone only. The overall risk of bias of included studies was low; all were RCTs and most trials used rigorous methods. Late systemic corticosteroids overall reduce mortality to the latest reported age (risk ratio (RR) 0.81, 95% confidence interval (CI) 0.66 to 0.99; 21 studies, 1428 infants; high-certainty evidence). Within the subgroups by drug, neither dexamethasone (RR 0.85, 95% CI 0.66 to 1.11; 19 studies, 993 infants; high-certainty evidence) nor hydrocortisone (RR 0.74, 95% CI 0.54 to 1.02; 2 studies, 435 infants; high-certainty evidence) alone clearly reduce mortality to the latest reported age. We found little evidence for statistical heterogeneity between the dexamethasone and hydrocortisone subgroups (P = 0.51 for subgroup interaction). Late systemic corticosteroids overall probably reduce BPD at 36 weeks' postmenstrual age (PMA) (RR 0.89, 95% CI 0.80 to 0.99; 14 studies, 988 infants; moderate-certainty evidence). Dexamethasone probably reduces BPD at 36 weeks' PMA (RR 0.76, 95% CI 0.66 to 0.87; 12 studies, 553 infants; moderate-certainty evidence), but hydrocortisone does not (RR 1.10, 95% CI 0.92 to 1.31; 2 studies, 435 infants; high-certainty evidence) (P < 0.001 for subgroup interaction). Late systemic corticosteroids overall probably reduce the combined outcome of mortality or BPD at 36 weeks' PMA (RR 0.85, 95% CI 0.79 to 0.92; 14 studies, 988 infants; moderate-certainty evidence). Dexamethasone probably reduces the combined outcome of mortality or BPD at 36 weeks' PMA (RR 0.75, 95% CI 0.67 to 0.84; 12 studies, 553 infants; moderate-certainty evidence), but hydrocortisone does not (RR 0.98, 95% CI 0.88 to 1.09; 2 studies, 435 infants; high-certainty evidence) (P < 0.001 for subgroup interaction). Late systemic corticosteroids overall have little to no effect on cerebral palsy (RR 1.17, 95% CI 0.84 to 1.61; 17 studies, 1290 infants; high-certainty evidence). We found little evidence for statistical heterogeneity between the dexamethasone and hydrocortisone subgroups (P = 0.63 for subgroup interaction). Late systemic corticosteroids overall have little to no effect on the combined outcome of mortality or cerebral palsy (RR 0.90, 95% CI 0.76 to 1.06; 17 studies, 1290 infants; high-certainty evidence). We found little evidence for statistical heterogeneity between the dexamethasone and hydrocortisone subgroups (P = 0.42 for subgroup interaction). Studies had few participants who were not intubated at enrolment; hence, it is not possible to make any meaningful comments on the effectiveness of late corticosteroids in preventing BPD in non-intubated infants, including those who might in the present day be supported by non-invasive techniques such as nasal continuous positive airway pressure or high-flow nasal cannula oxygen/air mixture, but who might still be at high risk of later BPD. Results of two ongoing studies are awaited.

AUTHORS' CONCLUSIONS

Late systemic postnatal corticosteroid treatment (started at seven days or more after birth) reduces the risks of mortality and BPD, and the combined outcome of mortality or BPD, without evidence of increased cerebral palsy. However, the methodological quality of studies determining long-term outcomes is limited, and no studies were powered to detect increased rates of important adverse long-term neurodevelopmental outcomes. This review supports the use of late systemic corticosteroids for infants who cannot be weaned from mechanical ventilation. The role of late systemic corticosteroids for infants who are not intubated is unclear and needs further investigation. Longer-term follow-up into late childhood is vital for assessment of important outcomes that cannot be assessed in early childhood, such as effects of late systemic corticosteroid treatment on higher-order neurological functions, including cognitive function, executive function, academic performance, behaviour, mental health, motor function, and lung function. Further RCTs of late systemic corticosteroids should include longer-term survival free of neurodevelopmental disability as the primary outcome.

Early (&lt; 7 days) systemic postnatal corticosteroids for prevention of bronchopulmonary dysplasia in preterm infants

BACKGROUND

Bronchopulmonary dysplasia (BPD) remains a major problem for infants born extremely preterm. Persistent inflammation in the lungs is important in its pathogenesis. Systemic corticosteroids have been used to prevent or treat BPD because of their potent anti-inflammatory effects.

OBJECTIVES

To examine the relative benefits and adverse effects of systemic postnatal corticosteroids commenced within the first six days after birth for preterm infants at risk of developing BPD.

SEARCH METHODS

We ran an updated search of the following databases on 25 September 2020: CENTRAL via CRS Web and MEDLINE via OVID. We also searched clinical trials databases and reference lists of retrieved articles for randomised controlled trials (RCTs). We did not include cluster randomised trials, cross-over trials, or quasi-RCTs.

SELECTION CRITERIA

For this review, we selected RCTs examining systemic (intravenous or oral) postnatal corticosteroid treatment started within the first six days after birth (early) in high-risk preterm infants. We included studies that evaluated the use of dexamethasone, as well as studies that assessed hydrocortisone, even when the latter was used primarily for management of hypotension, rather than for treatment of lung problems. We did not include trials of inhaled corticosteroids.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. We extracted and analysed data regarding clinical outcomes that included mortality, BPD, mortality or BPD, failure to extubate, complications during the primary hospitalisation, and long-term health and neurodevelopmental outcomes. We used the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

Use of the GRADE approach revealed that the certainty of evidence was high for the major outcomes considered, except for BPD at 36 weeks for all studies combined, which was downgraded one level to moderate because of evidence of publication bias. We included 32 RCTs (4395 infants). The overall risk of bias of included studies was low; all were RCTs, and most trials used rigorous methods. Early systemic corticosteroids overall have little or no effect on mortality to the latest reported age (risk ratio (RR) 0.95, 95% confidence interval (CI) 0.85 to 1.06; 31 studies, 4373 infants; high-certainty evidence), but hydrocortisone alone reduces mortality (RR 0.80, 95% CI 0.65 to 0.99; 11 studies, 1433 infants; high-certainty evidence). Early systemic corticosteroids overall probably reduce BPD at 36 weeks' postmenstrual age (PMA) (RR 0.80, 95% CI 0.73 to 0.88; 26 studies, 4167 infants; moderate-certainty evidence), as does dexamethasone (RR 0.72, 95% CI 0.63 to 0.82; 17 studies, 2791 infants; high-certainty evidence), but hydrocortisone has little to no effect (RR 0.92, 95% CI 0.81 to 1.06; 9 studies, 1376 infants; high-certainty evidence). Early systemic corticosteroids overall reduce the combined outcome of mortality or BPD at 36 weeks' PMA (RR 0.89, 95% CI 0.84 to 0.94; 26 studies, 4167 infants; high-certainty evidence), as do both dexamethasone (RR 0.88, 95% CI 0.81 to 0.95; 17 studies, 2791 infants; high-certainty evidence) and hydrocortisone (RR 0.90, 95% CI 0.82 to 0.99; 9 studies, 1376 infants; high-certainty evidence). Early systemic corticosteroids overall increase gastrointestinal perforation (RR 1.84, 95% CI 1.36 to 2.49; 16 studies, 3040 infants; high-certainty evidence), as do both dexamethasone (RR 1.73, 95% CI 1.20 to 2.51; 9 studies, 1936 infants; high-certainty evidence) and hydrocortisone (RR 2.05, 95% CI 1.21 to 3.47; 7 studies, 1104 infants; high-certainty evidence). Early systemic corticosteroids overall increase cerebral palsy (RR 1.43, 95% CI 1.07 to 1.92; 13 studies, 1973 infants; high-certainty evidence), as does dexamethasone (RR 1.77, 95% CI 1.21 to 2.58; 7 studies, 921 infants; high-certainty evidence) but not hydrocortisone (RR 1.05, 95% CI 0.66 to 1.66; 6 studies, 1052 infants; high-certainty evidence). Early systemic corticosteroids overall have little to no effect on the combined outcome of mortality or cerebral palsy (RR 1.03, 95% CI 0.91 to 1.16; 13 studies, 1973 infants; high-certainty evidence), nor does hydrocortisone (RR 0.86, 95% CI 0.71 to 1.05; 6 studies, 1052 infants; high-certainty evidence). However, early dexamethasone probably increases the combined outcome of mortality or cerebral palsy (RR 1.18, 95% CI 1.01 to 1.37; 7 studies, 921 infants; high-certainty evidence), In sensitivity analyses by primary intention for treatment with hydrocortisone (lung problems versus hypotension), there was little evidence of differences in effects on major outcomes of mortality, BPD, or combined mortality or BPD, by indication for the drug.

AUTHORS' CONCLUSIONS

Early systemic postnatal corticosteroid treatment (started during the first six days after birth) prevents BPD and the combined outcome of mortality or BPD. However, it increases risks of gastrointestinal perforation, cerebral palsy, and the combined outcome of mortality or cerebral palsy. Most beneficial and harmful effects are related to early treatment with dexamethasone, rather than to early treatment with hydrocortisone, but early hydrocortisone may prevent mortality, whereas early dexamethasone does not. Longer-term follow-up into late childhood is vital for assessment of important outcomes that cannot be assessed in early childhood, such as effects of early corticosteroid treatment on higher-order neurological functions, including cognitive function, executive function, academic performance, behaviour, mental health, motor function, and lung function. Further RCTs of early corticosteroids, particularly of hydrocortisone, should include longer-term survival free of neurodevelopmental disability as the primary outcome.

Cost-Effectiveness of Nasal High Flow Versus CPAP for Newborn Infants in Special-Care Nurseries

BACKGROUND

Treating respiratory distress in newborns is expensive. We compared the cost-effectiveness of 2 common noninvasive therapies, nasal continuous positive airway pressure (CPAP) and nasal high-flow (nHF), for newborn infants cared for in nontertiary special care nurseries.

METHODS

The economic evaluation was planned alongside a randomized control trial conducted in 9 Australian special care nurseries. Costs were considered from a hospital perspective until infants were 12 months of age. A total of 754 infants with respiratory distress, born ≥31 weeks' gestation and with birth weight ≥1200 g, <24 hours old, requiring noninvasive respiratory support and/or supplemental oxygen for >1 hour were recruited during 2015-2017. Inpatient costing records were obtained for 753 infants, of whom 676 were included in the per-protocol analysis. Two scenarios were considered: (1) CPAP versus nHF, with infants in the nHF group having "rescue" CPAP backup available (trial scenario); and (2) CPAP versus nHF, as sole primary support (hypothetical scenario). Effectiveness outcomes were rate of endotracheal intubation and transfer to a tertiary-level NICU.

RESULTS

As sole primary support, CPAP is more effective and on average cheaper, and thus is superior. However, nHF with back-up CPAP produced equivalent cost and effectiveness results, and there is no reason to make a decision between the 2 treatments on the basis of the cost or effectiveness outcomes.

CONCLUSIONS

Nontertiary special care nurseries choosing to use only 1 of the modes should choose CPAP. In units with both modes available, using nHF as first-line therapy may be acceptable if there is back-up CPAP.

Predictors and outcomes of extubation failure in extremely preterm infants

AIM

To determine predictors and outcomes of extubation failure in extremely preterm (EP) infants born <28 weeks' gestational age (GA).

METHODS

Retrospective clinical audit across two tertiary-level neonatal intensive care units in Melbourne, Australia. Two-hundred and four EP infants who survived to their first extubation from mechanical ventilation. Extubation failure (re-intubation) within 7 days after the first extubation.

RESULTS

Lower GA (odds ratio [OR] 0.71, 95% confidence interval (CI), 0.61-0.89, P < 0.001) and higher pre-extubation measured mean airway pressure (MAP) on the mechanical ventilator (OR 1.9 [95% CI 1.41-2.51], P < 0.001) predicted extubation failure. The area under a receiver operating characteristic curve for GA and MAP was 0.77 (95% CI 0.70-0.82). After adjustment for GA, infants who experienced extubation failure had higher rates of bronchopulmonary dysplasia (P < 0.001), post-natal systemic corticosteroid treatment (P < 0.001), airway trauma (P < 0.003), longer durations of treatment with mechanical ventilation (P < 0.001), non-invasive respiratory support (P < 0.001), supplemental oxygen therapy (P = 0.05) and longer hospitalisation (P = 0.025).

CONCLUSIONS

Lower GA and higher pre-extubation measured MAP were predictive of extubation failure within 7 days in extremely preterm infants. Extubation failure was associated with increased morbidity and extended periods of respiratory support and hospitalisation.

Outcomes after Introduction of Minimally Invasive Surfactant Therapy in Two Australian Tertiary Neonatal Units

OBJECTIVE

To assess the procedural and clinical outcomes associated with the introduction of minimally invasive surfactant therapy (MIST) into standard care at 2 tertiary Australian neonatal intensive care units.

STUDY DESIGN

A prospective audit was designed before the introduction of MIST in 2018, with data collected over a period of 18 months. Procedural data were completed by the clinical team performing MIST, including clinical observations, medication use, and adverse events. The audit team collected demographic data and subsequent clinical outcomes from medical records.

RESULTS

There were 135 MIST procedures recorded in 122 infants. For the included infants, the median gestation was 30^2/7 weeks (IQR, 27^6/7 to 32^2/7 weeks) and birth weight was 1439 g (IQR, 982-1958 g). During the MIST procedure, desaturation to a peripheral oxygen saturation of <80% was common, occurring in 75.2% of procedures. Other adverse events included need for positive pressure ventilation (10.6%) and bradycardia <100 beats per minute (13.3%). The use of atropine premedication was associated with a significantly lower incidence of bradycardia: 8.6% vs 52.9% (P < .01). Senior clinicians demonstrated higher rates of procedural success. The majority of infants (63.9%) treated with MIST did not require subsequent intubation and mechanical ventilation.

CONCLUSIONS

MIST can be successfully introduced in neonatal units with limited experience of this technique. The use of atropine premedication decreases the incidence of bradycardia during the procedure. Success rates can be optimized by limiting MIST to clinicians with greater competence in endotracheal intubation.

Predicting Nasal High-Flow Treatment Success in Newborn Infants with Respiratory Distress Cared for in Nontertiary Hospitals

OBJECTIVE

To evaluate demographic and clinical variables as predictors of nasal high-flow treatment success in newborn infants with respiratory distress cared for in Australian nontertiary special care nurseries.

STUDY DESIGN

A secondary analysis of the HUNTER trial, a multicenter, randomized controlled trial evaluating nasal high-flow as primary respiratory support for newborn infants with respiratory distress who were born ≥31 weeks of gestation and with birth weight ≥1200 g, and cared for in Australian nontertiary special care nurseries. Treatment success within 72 hours after randomization to nasal high-flow was determined using objective criteria. Univariable screening and multivariable analysis was used to determine predictors of nasal high-flow treatment success.

RESULTS

Infants (n = 363) randomized to nasal high-flow in HUNTER were included in the analysis; the mean gestational age was 36.9 ± 2.7 weeks and birth weight 2928 ± 782 g. Of these infants, 290 (80%) experienced nasal high-flow treatment success. On multivariable analysis, nasal high-flow treatment success was predicted by higher gestational age and lower fraction of inspired oxygen immediately before randomization, but not strongly. The final model was found to have an area under the curve of 0.65, which after adjustment for optimism was found to be 0.63 (95% CI, 0.57-0.70).

CONCLUSIONS

Gestational age and supplemental oxygen requirement may be used to guide decisions regarding the most appropriate initial respiratory support for newborn infants in nontertiary special care nurseries. Further prospective research is required to better identify which infants are most likely to be successfully treated with nasal high-flow.

TRIAL REGISTRATION

ACTRN12614001203640.

Predictors and Outcomes of Early Intubation in Infants Born at 28-36 Weeks of Gestation Receiving Noninvasive Respiratory Support

OBJECTIVE

To identify predictors and outcomes of early intubation in preterm infants with respiratory distress, and predictors of need for brief respiratory support (≤1 day).

STUDY DESIGN

Secondary analysis of data from a randomized trial comparing nasal high-flow with continuous positive airway pressure as primary respiratory support in preterm infants born at 28-36 weeks of gestation. Intubation was assessed within 72 hours of randomization.

RESULTS

There were 564 included infants with a mean (SD) gestational age of 32.0 (2.2) weeks and birth weight 1744 (589) g; 76 infants (13.5%) received early intubation. On multivariable analysis, lower gestational age and higher pre-randomization fraction of inspired oxygen (FiO₂) predicted intubation. A test based on gestational age of <30 weeks and an FiO₂ of ≥0.30 produced a likelihood ratio of 9.1. Intubation was associated with prolonged duration of respiratory support and supplemental oxygen, with pneumothorax and nasal trauma, and in infants born at <32 weeks of gestational, with bronchopulmonary dysplasia and patent ductus arteriosus requiring treatment. Greater gestational age and lower FiO₂ predicted the need for ≤1 day of respiratory support. A test based on a gestational age of ≥34 weeks and an FiO₂ of 0.21 produced a likelihood ratio of 4.7.

CONCLUSIONS

In preterm infants 28-36 week of gestation receiving primary noninvasive respiratory support, lower gestational age, and higher FiO₂ predicted need for intubation within 72 hours. Intubation was associated with adverse respiratory outcomes. Greater gestational age and lower FiO₂ predicted need for ≤1 day of respiratory support. It may be reasonable to defer the use of respiratory support in more mature infants with low FiO₂ requirements. TRIAL REGISTRATION AUSTRALIAN NEW ZEALAND CLINICAL TRIALS REGISTRY: ACTRN12613000303741.

Delivery room emergencies: Respiratory emergencies in the DR

The majority of newborns transition to extra uterine life without support. However, respiratory emergencies in the delivery room are a common occurrence. Whilst some situations are predictable e.g. the anticipated birth of an extremely preterm infant, others are less so. In this chapter we address the most frequent scenarios that result in delivery room respiratory emergencies and discuss the latest recommendations for their management. We outline the need for a trained resuscitation team and appropriate equipment to provide respiratory support at every birth. We address the basic care that all infants should receive, the detailed application of non-invasive ventilation and the use of advanced airway techniques. We discuss the unique challenges presented by extreme prematurity including umbilical cord management, use of supplemental oxygen, initial modes of respiratory support and surfactant delivery. We will explore optimal techniques in the management of infants with lung hypoplasia, pneumothorax and meconium aspiration.

Is Nasal High Flow Inferior to Continuous Positive Airway Pressure for Neonates?

Nasal high-flow therapy (nHF) is increasingly used for neonates, with perceived benefits including reduced rates of nasal trauma and parent and nursing staff preference. Current evidence suggests that although nHF is a reasonable alternative for postextubation support of preterm infants, continuous positive airway pressure is a superior modality for primary support of respiratory distress syndrome. Minimal evidence exists for use of nHF in extremely preterm infants less than 28 weeks' gestation. Depending on clinician preference, units may still choose nHF in some settings, although careful choice of appropriate patients, and availability of rescue continuous positive airway pressure, is essential.

Nasal High-Flow Therapy for Newborn Infants in Special Care Nurseries

BACKGROUND

Nasal high-flow therapy is an alternative to nasal continuous positive airway pressure (CPAP) as a means of respiratory support for newborn infants. The efficacy of high-flow therapy in nontertiary special care nurseries is unknown.

METHODS

We performed a multicenter, randomized, noninferiority trial involving newborn infants (<24 hours of age; gestational age, ≥31 weeks) in special care nurseries in Australia. Newborn infants with respiratory distress and a birth weight of at least 1200 g were assigned to treatment with either high-flow therapy or CPAP. The primary outcome was treatment failure within 72 hours after randomization. Infants in whom high-flow therapy failed could receive CPAP. Noninferiority was determined by calculating the absolute difference in the risk of the primary outcome, with a noninferiority margin of 10 percentage points.

RESULTS

A total of 754 infants (mean gestational age, 36.9 weeks, and mean birth weight, 2909 g) were included in the primary intention-to-treat analysis. Treatment failure occurred in 78 of 381 infants (20.5%) in the high-flow group and in 38 of 373 infants (10.2%) in the CPAP group (risk difference, 10.3 percentage points; 95% confidence interval [CI], 5.2 to 15.4). In a secondary per-protocol analysis, treatment failure occurred in 49 of 339 infants (14.5%) in the high-flow group and in 27 of 338 infants (8.0%) in the CPAP group (risk difference, 6.5 percentage points; 95% CI, 1.7 to 11.2). The incidences of mechanical ventilation, transfer to a tertiary neonatal intensive care unit, and adverse events did not differ significantly between the groups.

CONCLUSIONS

Nasal high-flow therapy was not shown to be noninferior to CPAP and resulted in a significantly higher incidence of treatment failure than CPAP when used in nontertiary special care nurseries as early respiratory support for newborn infants with respiratory distress. (Funded by the Australian National Health and Medical Research Council and Monash University; HUNTER Australian and New Zealand Clinical Trials Registry number, ACTRN12614001203640.).

A Randomized Controlled Trial of a Barrier Dressing to Reduce Nasal Injury in Preterm Infants Receiving Binasal Noninvasive Respiratory Support

OBJECTIVE

To determine whether the use of a hydrocolloid nasal barrier dressing during binasal continuous positive airway pressure (CPAP) therapy, compared with no barrier dressing, reduces the rate of nasal injury in very preterm and/or very low birth weight infants.

STUDY DESIGN

A single-center randomized controlled trial conducted in the neonatal intensive care unit at The Royal Women's Hospital, Melbourne. Eligible infants were born <30 weeks of gestation and/or with birth weight <1250 g, and had received ≥4 hours, but <48 hours, of CPAP. Infants were randomly allocated to receive either a hydrocolloid nasal barrier dressing during CPAP (barrier group), or no barrier dressing (no barrier group). The primary outcome was the incidence of any nasal injury during CPAP support, until the infant was both >30 weeks of postmenstrual age and >1250 g, unless CPAP therapy was stopped earlier. Nasal injury was regularly assessed by bedside nurses using a standardized form.

RESULTS

A total of 108 preterm infants were enrolled: 53 infants in the barrier group and 55 infants in the no barrier group. Infants in the barrier group had a significantly lower rate of nasal injury compared with the no barrier group: 18 of 53 (34%) vs 31 of 55 (56%), respectively (P = .02), number needed to treat; 5 infants. No significant differences were detected in any secondary respiratory outcomes, or in the rate of common neonatal morbidities.

CONCLUSIONS

Prophylactic use of a nasal barrier dressing within 48 hours of commencing treatment with binasal CPAP in very preterm or very low birth weight infants reduces nasal injury.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Register ACTRN12616000438459.

Refining the Use of Nasal High-Flow Therapy as Primary Respiratory Support for Preterm Infants

OBJECTIVE

To identify clinical and demographic variables that predict nasal high-flow (nHF) treatment failure when used as a primary respiratory support for preterm infants.

STUDY DESIGN

This secondary analysis used data from a multicenter, randomized, controlled trial comparing nHF with continuous positive airway pressure as primary respiratory support in preterm infants 28-36 completed weeks of gestation. Treatment success or failure with nHF was determined using treatment failure criteria within the first 72 hours after randomization. Infants in whom nHF treatment failed received continuous positive airway pressure, and were then intubated if failure criteria were again met.

RESULTS

There were 278 preterm infants included, with a mean gestational age (GA) of 32.0 ± 2.1 weeks and a birth weight of 1737 ± 580 g; of these, nHF treatment failed in 71 infants (25.5%). Treatment failure was moderately predicted by a lower GA and higher prerandomization fraction of inspired oxygen (FiO₂): area under a receiver operating characteristic curve of 0.76 (95% CI, 0.70-0.83). Nasal HF treatment success was more likely in infants born at ≥30 weeks GA and with prerandomization FiO₂ <0.30.

CONCLUSIONS

In preterm infants ≥28 weeks' GA enrolled in a randomized, controlled trial, lower GA and higher FiO₂ before randomization predicted early nHF treatment failure. Infants were more likely to be successfully treated with nHF from soon after birth if they were born at ≥30 weeks GA and had a prerandomization FiO₂ <0.30. However, even in this select population, continuous positive airway pressure remains superior to nHF as early respiratory support in preventing treatment failure.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry: ACTRN12613000303741.

Cost-Effectiveness Analysis of Nasal Continuous Positive Airway Pressure Versus Nasal High Flow Therapy as Primary Support for Infants Born Preterm

OBJECTIVE

To compare the cost-effectiveness of 2 common "noninvasive" modes of respiratory support for infants born preterm.

STUDY DESIGN

An economic evaluation was conducted as a component of a multicenter, randomized control trial from 2013 to 2015 enrolling infants born preterm at ≥28 weeks of gestation with respiratory distress, <24 hours old, who had not previously received endotracheal intubation and mechanical ventilation or surfactant. The economic evaluation was conducted from a healthcare sector perspective and the time horizon was from birth until death or first discharge. The cost-effectiveness of continuous positive airway pressure (CPAP) vs high-flow with "rescue" CPAP backup and high-flow without rescue CPAP backup (as sole primary support) were analyzed by using the hospital cost of inpatient stay in a tertiary center and the rates of endotracheal intubation and mechanical ventilation during admission.

RESULTS

Hospital inpatient cost records for 435 infants enrolled in all Australian centers were obtained. With "rescue" CPAP backup, an incremental cost-effectiveness ratio was estimated of A$179 000 (US$123 000) per ventilation avoided if CPAP was used compared with high flow. Without rescue CPAP backup, cost per ventilation avoided was A$7000 (US$4800) if CPAP was used compared with high flow.

CONCLUSIONS

As sole primary support, CPAP is highly likely to be cost-effective compared with high flow. Neonatal units choosing to use only one device should apply CPAP as primary respiratory support. Compared with high-flow with rescue CPAP backup, CPAP is unlikely to be cost-effective if willingness to pay per ventilation avoided is less than A$179 000 (US$123 000).

Cerebral oxygenation during skin-to-skin care in preterm infants not receiving respiratory support

OBJECTIVE

Skin-to-skin care (SSC) has proven benefits in preterm infants, but increased hypoxic and bradycardic events have been reported. This may make clinicians hesitant to recommend SSC as standard care. We hypothesised that regional cerebral oxygenation (rStO₂) measured with near infrared spectroscopy is not worse during SSC compared with standard incubator care.

DESIGN

Prospective, observational, non-inferiority study.

SETTING

Single tertiary perinatal centre in Australia.

PATIENTS

Forty preterm infants (median (IQR) 30.6 (29.1-31.7) weeks' gestation) not receiving respiratory support were studied on day 14 (8-38).

INTERVENTIONS

Recordings during 90 min of incubator care, followed by 90 min of SSC. Each infant acted as their own control and caregivers were blinded to the rStO₂ measurements.

MAIN OUTCOME MEASURES

The primary outcome was the mean difference in rStO₂ between SSC and incubator care. The prespecified margin of non-inferiority was -1.5%. Secondary outcomes included heart rate (HR), peripheral oxygen saturation (SpO₂), time in quiet sleep, temperature and hypoxic (SpO₂ <80% for >5 s) or bradycardic events (HR <80 bpm for >5 s) and time spent in cerebral hypoxia (rStO₂<55%) and hyperoxia (rStO₂>85%).

RESULTS

Mean (SD) rStO₂ was lower during SSC compared with incubator care: 73.6 (6.0)% vs 74.8 (4.6)%, mean difference (95% CI) 1.3 (2.2 to 0.4)%. HR was 5 bpm higher, SpO₂ 1% lower and time in quiet sleep 24% longer during SSC. Little evidence of a difference was observed in temperature. The number of hypoxic or bradycardic events as well as the proportion of time spent in cerebral hypoxia and hyperoxia was very low in both periods.

CONCLUSIONS

Mean rStO₂ was marginally lower during SSC without observed differences in hypoxic or bardycardic events but an increase in time spent in quiet sleep.

TRIAL REGISTRATION NUMBER

This trial is linked to Australian New Zealand Clinical Trials Registry: identifier 12616000240448. It was registered pre-results.

Nasal injury in preterm infants receiving non-invasive respiratory support: a systematic review

OBJECTIVE

Binasal prongs are the most commonly used interface for the delivery of nasal positive airway pressure (CPAP) to preterm infants. However, they are associated with pressure-related nasal injury, which causes pain and discomfort. Nasal injury may necessitate a change in interface and occasionally damage is severe enough to require surgical repair. We aim to determine the incidence and risk factors for nasal injury in preterm infants, and to provide clinicians with strategies to effectively prevent and treat it.

DESIGN

We conducted a systematic search of databases including MEDLINE (PubMed including the Cochrane Library), EMBASE, CINAHL and Scopus. Included studies enrolled human preterm infants and were published prior to 20 February 2017.

RESULTS

Forty-five studies were identified, including 14 ra ndomised controlled trials, 10 observational studies, two cohort studies, eight case reports and 11 reviews. The incidence of nasal injury in preterm infants ranged from 20-100%. Infants born <30 weeks' gestation are at highest risk. Strategies shown to reduce nasal injury included: nasal barrier dressings (2 studies, n=244, risk ratio (RD) -0.12, 95%, CI - 0.20 to -0.04), nasal high flow therapy as an alternative to binasal prong CPAP (7 studies, n=1570, risk difference (RD) -0.14, 95% CI -0.17 to -0.10), and nasal masks rather than binasal prongs (5 studies, n=544, RR 0.80, 95% CI 0.64 to 1.00).

CONCLUSIONS AND RELEVANCE

Nasal injury is common in preterm infants born <30 weeks' gestational age receiving CPAP via binasal prongs. Larger randomised trials are required to fully evaluate strategies to reduce nasal injury.

Retrospective Consent in a Neonatal Randomized Controlled Trial

BACKGROUND AND OBJECTIVES

The requirement for prospective consent in clinical trials in acute settings may result in samples unrepresentative of the study population, potentially altering study findings. However, using retrospective consent may raise ethical issues. We assessed whether using retrospective consent affected recruitment, participant characteristics, and outcomes within a randomized controlled trial.

METHODS

We conducted a secondary analysis of a randomized trial, which compared nasal high flow (nHF) with nasal continuous positive airway pressure (CPAP) for primary respiratory support in preterm infants. In Era 1, all infants were consented prospectively; in Era 2, retrospective consent was available. We assessed inclusion rates of eligible infants, demographic data, and primary trial outcome (treatment failure within 72 hours).

RESULTS

In Era 1, recruitment of eligible infants was lower than in Era 2: 111 of 220 (50%) versus 171 of 209 (82%), P < .001; intrapartum antibiotic administration was lower: 23 of 111 (21%) versus 84 of 165 (51%), P < .001; full courses of antenatal steroids were higher: 86 of 111 (78%) versus 103 of 170 (61%), P = .004; and more infants received pre-randomization CPAP: 77 of 111 (69%) versus 48 of 171 (28%), P < .001. In Era 1, nHF failure (15 of 56, 27%) and CPAP failure (14 of 55, 26%) rates were similar, P = .9. In Era 2, failure rates differed: 24 of 85 (28%) nHF infants versus 13 of 86 (15%) CPAP infants, P = .04. The χ² interaction test was nonsignificant (P = .20).

CONCLUSIONS

The use of retrospective consent resulted in greater recruitment and differences in risk factors between eras. Using retrospective consent altered the study sample, which may be more representative of the whole population. This may improve scientific validity but requires further ethical evaluation.

A multicentre, randomised controlled, non-inferiority trial, comparing nasal high flow with nasal continuous positive airway pressure as primary support for newborn infants with early respiratory distress born in Australian non-tertiary special care nurseries (the HUNTER trial): study protocol

INTRODUCTION

Nasal high-flow (nHF) therapy is a popular mode of respiratory support for newborn infants. Evidence for nHF use is predominantly from neonatal intensive care units (NICUs). There are no randomised trials of nHF use in non-tertiary special care nurseries (SCNs). We hypothesise that nHF is non-inferior to nasal continuous positive airway pressure (CPAP) as primary support for newborn infants with respiratory distress, in the population cared for in non-tertiary SCNs.

METHODS AND ANALYSIS

The HUNTER trial is an unblinded Australian multicentre, randomised, non-inferiority trial. Infants are eligible if born at a gestational age ≥31 weeks with birth weight ≥1200 g and admitted to a participating non-tertiary SCN, are <24 hours old at randomisation and require non-invasive respiratory support or supplemental oxygen for >1 hour. Infants are randomised to treatment with either nHF or CPAP. The primary outcome is treatment failure within 72 hours of randomisation, as determined by objective oxygenation, apnoea or blood gas criteria or by a clinical decision that urgent intubation and mechanical ventilation, or transfer to a tertiary NICU, is required. Secondary outcomes include incidence of pneumothorax requiring drainage, duration of respiratory support, supplemental oxygen and hospitalisation, costs associated with hospital care, cost-effectiveness, parental stress and satisfaction and nursing workload.

ETHICS AND DISSEMINATION

Multisite ethical approval for the study has been granted by The Royal Children's Hospital, Melbourne, Australia (Trial Reference No. 34222), and by each participating site. The trial is currently recruiting in eight centres in Victoria and New South Wales, Australia, with one previous site no longer recruiting. The trial results will be published in a peer-reviewed journal and will be presented at national and international conferences.

TRIAL REGISTRATION NUMBER

Australian and New Zealand Clinical Trials Registry (ANZCTR): ACTRN12614001203640; pre-results.