This NIHR-funded systematic review and cost-effectiveness study found that pre-hospital (i.e. in the ambulance) non-invasive ventilation in the form of continuous positive airway pressure for people with acute respiratory failure, can reduce both the risk of dying and the need for ventilation in intensive care. The small device used by trained ambulance personnel was more effective than standard care, giving oxygen and standard medical treatment only, but was more expensive. No trials in the review were based in the UK. Emergency care services between countries may vary substantially, thus limiting the applicability of the findings to the NHS.
The implementation of a change in practice for people with acute respiratory failure is likely to require extra resources such as equipment, training and reorganisation of emergency service in the NHS, but based on this study it seems like it could be value for money. Further UK-based evidence is likely to be required before pre-hospital non-invasive ventilation in the NHS can be recommended.
Why was this study needed?
Acute respiratory failure is a common life-threatening medical emergency, particularly in older people, with low levels of oxygen and raised carbon dioxide in the blood. It can be caused by a range of heart and lung conditions such as heart failure, chronic obstructive pulmonary disease (COPD), and pneumonia or acute lower respiratory infection. In 2009, 379,731 people went to hospital in England for these conditions with about 14% of people dying within 30 days.
One hospital-based treatment device delivers continuous positive airway pressure (CPAP) using a tight-fitting mask over their mouth and nose. This helps patients with various problems breathe more easily. People with respiratory failure are often given oxygen treatment in the ambulance on the way to the hospital. The risk of death in people with respiratory problems has been found to increase with distance travelled to hospital. The NIHR funded this study to find out whether giving oxygen using either of two non-invasive devices in the ambulance (pre-hospital) reduced the risk of people with acute respiratory failure dying or needing to be put on a ventilator when they got to hospital, and to see how the extra costs weighed up against the benefits.
What did this study do?
This systematic review identified two quasi-randomised and eight randomised controlled trials comparing pre-hospital non-invasive ventilation with standard care - giving oxygen and standard medical treatment only. Two types of device were investigated: continuous positive airway pressure (CPAP) in six trials and bilevel inspiratory positive airway pressure (BiPAP) in four trials. CPAP provides constant pressure as the person breathes in and out, while BiPAP provides high pressure when they breathe in and low pressure when they breathe out. Treatments were compared directly within trials, and indirectly across trials, using network meta-analysis. This gives an overall measure of the effect of one treatment compared to another treatment, even if trials did not compare treatments directly.
The trials included in the review were generally small and might represent selected patient groups. The treatments compared varied across the trials, and the pooled analysis may not have been able to detect potentially important differences in outcomes.
The review included a cost-effectiveness analysis where they looked at the costs of giving pre-hospital CPAP for each future year of life that the person lived in good health (a quality adjusted life year, QALY).
What did it find?
- The pooled results of six trials found that pre-hospital CPAP reduced the risk of dying compared with standard care (odds ratio [OR] 0.41, 95% Credible Interval [CrI] 0.20 to 0.77). Follow-up times ranged from 30 days to hospital discharge or death.
- The pooled results of five trials also found that pre-hospital CPAP reduced the risk of being put on a ventilator compared with standard care (OR 0.32, 95% CrI 0.17 to 0.62).
- For BiPAP, there were no significant differences compared with standard care for risk of death (three trials) or needing a ventilator (four trials).
- Pre-hospital CPAP was more effective than standard care but also more expensive. Pre-hospital CPAP cost £20,514 per QALY gained. Results meant that it had almost a 50% chance of being cost effective at the £20,000 per QALY threshold normally set for determining whether treatments are a good use of NHS resources.
What does current guidance say on this issue?
Pre-hospital ventilation is not usually used by UK NHS ambulance service. The 2013 update of the UK Ambulance Services Clinical Practice Guidelines for the first time recommended the use of pre-hospital CPAP on the basis of expert consensus. This treatment has not been researched extensively in settings outside of hospitals.
What are the implications?
This systematic review found that pre-hospital CPAP was more effective than standard care for the two outcomes examined, and was reasonable value for money compared to alternatives for the NHS (at the usual £20,000 per QALY NHS threshold).
Importantly, none of the trials took place in an NHS setting, and they were limited by small sample sizes and differences in the treatment offered.
With the current level of evidence it is uncertain whether the implementation of pre-hospital CPAP would be appropriate for the NHS. For example, the implementation for people with acute respiratory failure is likely to require substantial resources of equipment, training and reorganisation of emergency service in the NHS.
Pandor A, Thokala P, Goodacre S, et al. Pre-hospital non-invasive ventilation
for acute respiratory failure: a systematic review and cost-effectiveness
evaluation. Health Technol Assess. 2015 Jun;19(42):1-102.
This project was funded by the National Institute for Health Research Health Technology Assessment programme (project number 11/36/09)
BMJ Best practice. Acute respiratory failure. London: BMJ Publishing Group; 2014
Joint Royal Colleges Ambulance Liaison Committee. UK Ambulance Services Clinical Practice Guidelines 2013. London: Association of Ambulance Chief Executives; 2013
Stefan MS, Shieh MS, Pekow PS, et al. Epidemiology and outcomes of acute respiratory failure in the United
States, 2001 to 2009: a national survey. J Hosp Med. 2013;8:76-82.
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