Condition category
Circulatory System
Date applied
Date assigned
Last edited
Retrospectively 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 Cnristine Roffe


Contact details

Elderly Care Unit
North Staffs Combined Healthcare Trust
City General
Newcastle Road
United Kingdom
+44 (0)1782 552066

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

The Stroke Oxygen Pilot Study: a randomised controlled pilot study of the effects of routine oxygen supplementation on functional outcome after acute stroke


SOS Pilot Study

Study hypothesis

The main hypothesis to be tested is that routine fixed dose oxygen treatment during the first three days after an acute stroke will reduce death and disability during the first six months after the stroke. It is likely that the proposed pilot study is too small to answer the research question, but it is necessary to perform this pilot trial in preparation for a larger multicentre study that will then answer the above research question.

The main objective of this pilot trial is to assess differences in main outcomes between treatment groups (stroke patients who received oxygen treatment compared to stroke patients who did not receive oxygen treatment). This will be used to calculate the study size for the planned multi-centre outcome trial.

As of 01/05/2008 this pilot study was updated. Any changes to this record can be see in the relevant field, under the update date of 01/05/2008. Please note that the anticipated end date of this trial has been changed as the trial has now finished recruiting. The previous anticipated end date of this trial was 01/11/2008.

The multicentre study to this trial is also in the ISRCTN Register, and can be found at

Ethics approval

Added as of 01/05/2008:
Ethics approval received from the Multicentre Research Ethics Committee on the 6th October 2004 (ref: 04/Q2604/73).

Study design

Prospective randomised open study

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Patient information material can be found at




300 patients with a clinical diagnosis of acute stroke will be recruited within 24 hours of hospital admission.

This is a prospective randomised open study of the effects of early routine fixed dose oxygen supplementation compared with standard care on functional outcome (death and disability) at six months after acute stroke. An open design was chosen because placebo treatment (room air) would have at least some of the potential side effects of active treatment (e.g. limitation of mobility and risk of infection) without having any beneficial effects and might therefore bias the results in favour of the treatment group. Patients will be randomised to one of two treatment groups:
1. Treatment group 1: no routine oxygen supplementation during the first three days of randomisation
2. Treatment group 2: oxygen per nasal cannula continuously (day and night) at a flow rate of 3 l/min if baseline oxygen saturation is less than 93% or at a rate of 2 l/min (if baseline oxygen saturation is greater than 93%) with humidification during the first three days after randomisation. Patients who develop definite indications or contra-indications for oxygen treatment during the trial will be treated according to clinical need, irrespective of study treatment allocation.

The main outcomes will be ascertained at six months by postal questionnaire. It is likely that participants will have forgotten which treatment group they were in six months after the intervention, and it is therefore unlikely that treatment allocation will bias their answers. We will assess whether patients remember their treatment allocation by including this as a question in the six-month assessment questionnaire.

Overnight pulse oximetry and day three assessment: in order to ascertain whether the prescribed oxygen supplementation effectively prevents hypoxia, pulse oximetry will be performed overnight on night two while the patient is receiving oxygen or no oxygen. We will also be able to quantify the time patients spent with an oxygen saturation level above the normal range. This is necessary to fine-tune the dosage schedule for the planned multicentre outcome study.

The day three assessment (Assessment Form 1) will document compliance with the trial treatment, relevant aspects of the patient's past medical history, and the stroke type (Oxfordshire Community Project Stroke Classification), and confirm completion of the overnight pulse oximetry. If incomplete, pulse oximetry will be repeated on night three of treatment.

The week one assessment (Assessment form 2) is designed to screen for potential adverse effects of oxygen and includes indicators of infection, stress (tachycardia and hypertension), behavioural disturbances, cognitive function, and neurological deterioration. If the patient is well enough to cooperate the researcher will discuss the 6 months assessment and find out the preferred contact(s) for mailing the questionnaire.

The month three assessment (Assessment Form 3) documents the length of stay in hospital, and discharge destination. The discharge address and the contact details of the GP are recorded in preparation for the 6 months follow-up. It will be completed using information from the HISS/CHIPS hospital computer system and patient notes.

The month six assessment (Assessment Form 4) will provide the main outcome (death and disability at six months) data for testing the trial hypothesis of the planned larger study. It consists of a questionnaire that will be sent to the patient's preferred contact address (if known) or the discharge address. Outcomes will be assessed using well-validated scales (Rankin, three-point Barthel, EuroQoL, the Nottingham Extended Activities of Daily Living Index).

Intervention type



Not Specified

Drug names


Primary outcome measure

Death and disability using the following measures:
1. Death and disability (Rankin Score greater than three) at six months
2. Scandinavian Stroke Scale at week one
3. Mortality up to six months
4. Rankin Score at six months
5. Nottingham EADL score at six months

Secondary outcome measures

Added as of 01/05/2008:
1. Potential side effects of oxygen treatment
2. Frequency of protocol violation
3. National Institutes of Health Stroke Scale (NIHSS)/Scandinavian Stroke Scale (SSS) at one week
4. Oxygen saturation while on treatment

To assess the feasibility of recruiting stroke patients within 24 hours of hospital admission.

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

Adult patients (either sex) will be eligible for trial inclusion if they were admitted with symptoms of an acute stroke within the preceding 24 h and if, in the doctor's opinion, there is no clear indication for and no clear contraindication against oxygen treatment (added as of 01/05/2008).

1. Identification:
All patients admitted to the University Hospital of North Staffordshire with an acute stroke will be eligible to be considered for trial inclusion. They will be identified as potential participants by a member of the research team or by staff in the Medical Admissions Unit, Accident and Emergency (A&E), or the Emergency Admission Unit.

2. Approach:
Potential participants will be approached by a member of the research team or the doctor admitting the patient. Because hypoxia is more likely to be detrimental early after the stroke, when the ischaemic penumbra either recovers or expands it is crucial to include patients as soon as possible after the stroke onset into the trial. Patients will therefore be approached as soon as they enter hospital via the Medical Assessment Unit or the Accident and Emergency department, or at the next earliest opportunity on a medical ward up to 24 hours after admission.

3. Recruitment:
The study will be explained to potential participants and they will be invited to take part. The patient will then be given an information leaflet. If he/she agrees to take part they will be recruited to the trial after informed consent has been given. If the patient does not disagree, but is incompetent to give fully informed consent, assent will be sought from the next of kin using the same procedure.

Participant type


Age group




Target number of participants

300 patients

Participant exclusion criteria

Added as of 01/05/2008:
1. Patients who have recognised indications for oxygen treatment such as:
1.1. Oxygen saturation on air less than 90%
1.2. Hypoxia associated with acute left ventricular failure, severe pneumonia and pulmonary embolus
1.3. Chronic respiratory failure treated with long term oxygen at home
2. Recognised contra-indications to fixed dose oxygen treatment (2 - 3 l/min/vy nasal tubes): type II respiratory failure (contra-indication to fixed dose oxygen as given in this trial)
3. The stroke is not the patient's main clinical problem: the patient has another serious life-threatening illness likely to lead to death within the next few months

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Elderly Care Unit
United Kingdom

Sponsor information


Department of Health

Sponsor details

Richmond House
79 Whitehall
United Kingdom
+44 (0)20 7307 2622

Sponsor type




Funder type


Funder name

North Staffordshire Research and Development Consortium (UK) - North Staffordshire Combined Healthcare Trust

Alternative name(s)

Funding Body Type

Funding Body Subtype


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

1. Pilot study:
2. Comparative study:
3. Conversion factor development:
4. 2011 results in
5. 2013 results in:

Publication citations

  1. Pilot study

    Ali K, Sills S, Roffe C, The effect of different doses of oxygen administration on oxygen saturation in patients with stroke., Neurocrit Care, 2005, 3, 1, 24-26, doi: 10.1385/NCC:3:1:024.

  2. Comparative study

    Ali K, Cheek E, Sills S, Crome P, Roffe C, Day-night differences in oxygen saturation and the frequency of desaturations in the first 24 hours in patients with acute stroke., J Stroke Cerebrovasc Dis, 16, 6, 239-244, doi: 10.1016/j.jstrokecerebrovasdis.2007.07.004.

  3. Conversion factor development

    Ali K, Cheek E, Sills S, Crome P, Roffe C, Development of a conversion factor to facilitate comparison of National Institute of Health Stroke Scale scores with Scandinavian Stroke Scale scores., Cerebrovasc. Dis., 2007, 24, 6, 509-515, doi: 10.1159/000110420.

  4. Results

    Roffe C, Ali K, Warusevitane A, Sills S, Pountain S, Allen M, Hodsoll J, Lally F, Jones P, Crome P, The SOS pilot study: a RCT of routine oxygen supplementation early after acute stroke--effect on recovery of neurological function at one week., PLoS ONE, 2011, 6, 5, e19113, doi: 10.1371/journal.pone.0019113.

  5. Results

    Ali K, Warusevitane A, Lally F, Sim J, Sills S, Pountain S, Nevatte T, Allen M, Roffe C, The stroke oxygen pilot study: a randomized controlled trial of the effects of routine oxygen supplementation early after acute stroke--effect on key outcomes at six months, PLoS One, 2013, 8, 6, doi: 10.1371/journal.pone.0059274.

Additional files

Editorial Notes