Condition category
Neonatal Diseases
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
No longer recruiting
Publication status

Plain English Summary

Not provided at time of registration

Trial website

Contact information



Primary contact

Dr Peter Brocklehurst


Contact details

University of Oxford
Old Road Campus
United Kingdom
+44 (0)1865 289719

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Which oxygen saturation level should we use for very premature infants? A randomised controlled trial



Study hypothesis

Does varying the concentration of inspired oxygen so as to target a low (85-89%) versus a high (91-95%) functional arterial oxygen saturation (SpO2), from the day of birth until the baby is breathing air (or until the baby has reached a postmenstrual age of at least 36 weeks) affect the incidence of:
1. Retinopathy of prematurity (plus disease or Grade 3 and 4) and its two year outcome?
2. Other surgery (for conditions such as patent ductus arteriosus, post-haemorrhagic ventriculomegaly or necrotising enterocolitis)?
3. Chronic lung disease?
4. Death or severe neurosensory disability on assessment 2 years after the child was due to be born?
5. Poor weight gain and head growth between birth and 36 weeks postmenstrual age, and between birth and 2 years of age?

Ethics approval

Trent Multi-Centre Ethics Committee, 02/05/2007, ref: 06/MRE04/91

Study design

Double-blind randomised controlled trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Information leaflet for parents:




The intervention is to maintain functional oxygen saturations in the range 85-89% or 91-95%. Masimo radical oximeters (Irvine, CA) will be used to monitor oxygen saturation levels. The oximeters will be modified to display and store a figure that is either 3% above or 3% below the 'true' oxygen saturation between 85% and 95% as computed by the machines' internal algorithm. Outside of these limits the oximeter will display the true value. Staff will aim for an oximeter reading of between 88 and 92%. This will, therefore, generate two trial groups: one for which oxygen saturation is maintained at 85-89%, and one for which it is maintained at 91-95%.

Added 30/11/2015:
The Masimo oximeters used in the trial were revised on 08/12/2008 to correct an artefact in their calibration algorithm. Achieved oxygen saturation distributions were clearly different with the revised oximeters. On 02/11/2009 the Data Monitoring Committee recommended that the Trial Steering Committee should consider whether the data from the two oximeter types should be considered separately. On 01/12/2010, blind to any outcome data, the Trial Steering Committee recommended to the Chief Investigator to change the protocol and to enrol the originally intended target sample size of 1,200 infants using the revised oximeters and to make this the primary analysis outcome population for the trial. A secondary analysis was planned to include the results of the infants treated with the original oximeters.

Intervention type



Not Applicable

Drug names

Primary outcome measure

Death or serious neurosensory disability at 2 years corrected for prematurity

Added 30/11/2015:
Serious neurosensory disability was defined before recruitment commenced as: a cognitive score of <70 (i.e. more than 2 standard deviations below the mean) using the Bayley Scale of Infant Development (BSID-3); severe visual loss (certifiable as legally blind or partially sighted); severe cerebral palsy (unable to walk without help at 2 years); deafness requiring (or too severe to benefit from) a hearing aid.

Before the neurodevelopmental assessments even began, a cut-off score <85 on the cognitive or language component of the Bayley-III was decided because this matched a cognitive score <70 on the BSID-II that was used from the outset in some of the NeOProM trials. Bayley-III assessments could not always be arranged. To minimize the risk of bias from post-randomization exclusions, alternative corroborative measures of cognition and language were therefore pre-specified in the Statistical Analysis Plan (SAP) on 27/11/2013 and in the final version of the SAP that was signed off on 31/03/2014 prior to unblinding or analysis of the results. Serious neurosensory disability was assessed blind to trial group assessment. Paediatricians completed a follow-up assessment including information about visual function, hearing, gross motor function, the results of the Bayley-III test or any other test of cognitive function, an assessment of language skills, an assessment of the degree of any developmental delay and information about general health. Parents were asked to fill in a parental questionnaire including information about general health, strengths and difficulties and Parent Report of Children’s Abilities–Revised (PARCA-R). If a Paediatrician report could not be obtained or was incomplete the missing information was sought from the family General Practitioner (GP). Tests reported on the Paediatrician form included the Wechsler Preschool and Primary Scales of Intelligence (WPPSI-III), the Denver Developmental Screening Test, the Griffiths Mental Development Scales, and the Schedule of Growing Skills. The primary outcome of death or serious neurosensory disability was first defined by death, severe visual loss, deafness or cerebral palsy. In the remaining infants the cognitive measure of serious neurosensory disability was first defined as a cognitive or language score <85 on the Bayley-III. If this was not available the outcome was classified using the Paediatrician’s assessment of developmental delay or language delay and then by the GP assessment. Free text on the forms returned by health professionals and parents was assessed independently by two assessors masked to group assignment to adjudicate cognitive outcome in a small number of cases. A secondary analysis of the results was pre-specified, excluding the alternative measures of disability.

Secondary outcome measures

1. Respiratory outcomes:
1.1. Days of endotracheal intubation
1.2. Days of nasal continuous positive airway pressure
1.3. Supplemental oxygen at a postmenstrual age of 36 weeks
1.4. Days of oxygen prior to home discharge
1.5. Days in oxygen after home discharge
2. Retinopathy of prematurity (ROP), plus disease, stage 3 and 4 disease
3. Patent ductus arteriosus requiring medical or surgical treatment
4. Necrotising enterocolitis, Bell stage 3 or 4
5. Changes in weight and head circumference from birth to 36 weeks postmenstrual age, and 2 years after delivery was due
6. Retinal structure when last seen for ophthalmic review; outcomes at age 2 years
7. Re-admissions to hospital until 2 years after delivery was due (and their cause)
8. Cerebral palsy (and its severity)
9. Visual disability
10. Deafness
11. Developmental delay using the Bayley Test Mental Developmental Index (MDI)
12. Other disability not classifiable as neurosensory in origin
13. All postneonatal (>27 days) deaths, together with their immediate and underlying cause

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

Infants are eligible if they are:
1. Less than 28 weeks gestation at birth
2. Less than 12 h old (24 h if the baby is outborn)
3. The clinician and parents are substantially uncertain which SpO2 is better

Participant type


Age group




Target number of participants

1200 (973 recruited by end of recruitment)

Participant exclusion criteria

Recruitment is not appropriate if there is no realistic prospect of survival, or follow-up is unlikely to be possible

Recruitment start date


Recruitment end date



Countries of recruitment

Ireland, United Kingdom

Trial participating centre

University of Oxford
United Kingdom

Sponsor information


University of Oxford (UK)

Sponsor details

c/o Kathryn Dally (Acting Head)
Medical Research Services Office
Medical School Office
Level 3
John Radcliffe Hospital
United Kingdom
+44 (0)1865 289728

Sponsor type




Funder type


Funder name

Medical Research Council (UK)

Alternative name(s)


Funding Body Type

government organisation

Funding Body Subtype

National government


United Kingdom

Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Basic results (scientific)

Publication list

2013 results in:
2016 results in:

Publication citations

  1. Results

    Stenson BJ, Tarnow-Mordi WO, Darlow BA, Simes J, Juszczak E, Askie L, Battin M, Bowler U, Broadbent R, Cairns P, Davis PG, Deshpande S, Donoghoe M, Doyle L, Fleck BW, Ghadge A, Hague W, Halliday HL, Hewson M, King A, Kirby A, Marlow N, Meyer M, Morley C, Simmer K, Tin W, Wardle SP, Brocklehurst P, Oxygen saturation and outcomes in preterm infants., N. Engl. J. Med., 2013, 368, 22, 2094-2104, doi: 10.1056/NEJMoa1302298.

  2. Results

    BOOST-II Australia and United Kingdom Collaborative Groups, Tarnow-Mordi W, Stenson B, Kirby A, Juszczak E, Donoghoe M, Deshpande S, Morley C, King A, Doyle LW, Fleck BW, Davis PG, Halliday HL, Hague W, Cairns P, Darlow BA, Fielder AR, Gebski V, Marlow N, Simmer K, Tin W, Ghadge A, Williams C, Keech A, Wardle SP, Kecskes Z, Kluckow M, Gole G, Evans N, Malcolm G, Luig M, Wright I, Stack J, Tan K, Pritchard M, Gray PH, Morris S, Headley B, Dargaville P, Simes RJ, Brocklehurst P, Outcomes of Two Trials of Oxygen-Saturation Targets in Preterm Infants, N Engl J Med, 2016 , 374, 8, 749-760, doi: 10.1056/NEJMoa1514212.

Additional files

Editorial Notes

08/03/2016: Publication reference added. On 02/12/2013 the overall trial end date was changed from 30/11/2013 to 31/05/2014. On 06/12/2012 Ireland was added to the countries of recruitment.