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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.
This NIHR-funded trial found no evidence that long-term home oxygen therapy improves symptoms or quality of life for people with severe chronic heart failure. There were encouraging signs after three months but these were not sustained at six months by which time there was no difference between the oxygen therapy group, who continued to receive best medical care, and the control group. The trial was stopped early due to poor adherence to the therapy and so was unable to furnish strong evidence.
Patients were prescribed 15 hours a day of oxygen therapy, but only used on average just over five hours; only one in ten participants used the therapy as prescribed. These limitations mean that the results need to be treated with caution. However, given the lack of clear evidence of benefit and the expensive and burdensome nature of home oxygen therapy, the treatment is unlikely to be cost-effective.
Why was this study needed?
Chronic heart failure affects at least 1% of the population and is responsible for around 4% of all admissions to hospital in the UK. It is estimated that the cost of heart failure is around 2% of the total NHS budget; nearly three-quarters of this is due to the costs of hospitalisation.
People with severe chronic heart failure often suffer from breathlessness. Home oxygen therapy is commonly prescribed in order to relieve symptoms although, unlike the situation for patients with chronic obstructive pulmonary disease, there is no evidence to support the use of home oxygen therapy in patients with chronic heart failure.
The NIHR funded this trial to look at whether or not home oxygen therapy improved the quality of life of people with severe chronic heart failure.
What did this study do?
This was a randomised controlled trial of long-term home oxygen therapy versus standard care of 114 patients with severe chronic heart failure. Patients were on average 70 years of age and 70% were men. All of them had severe symptoms of breathlessness either at rest or after minimal exertion. Patients were excluded if they had hypoxia, low oxygen levels in the blood.
Oxygen therapy was delivered in the patients’ homes via a machine called an oxygen concentrator. Oxygen was prescribed for 15 hours per day, similar to standard practice for patients with chronic obstructive pulmonary disease. The oxygen concentrator delivered air with about 28% oxygen, up from the 20.9% found in normal room air. All participants received standard medical therapy.
The original target was 222 patients but the trial was stopped because of poor patient adherence to the prescribed therapy. The trial was therefore underpowered and so the results need to be treated with caution.
What did it find?
- After three months, there was an additional improvement in quality of life of about five points on a 105 point scale in the oxygen therapy group compared to the control group (change in adjusted mean Minnesota Living with Heart Failure questionnaire score -5.47, 95% confidence interval -10.54 to -0.41). Breathlessness scores also improved.
- However, after six months there was no difference. Both groups had improved by about five to six points on a 105 point scale.
- Only 11% of patients reported using the therapy as prescribed. Participants used the oxygen for an average of a little over five hours a day, rather than the 15 hours prescribed.
What does current guidance say on this issue?
NICE does not have guidance on the use of home oxygen therapy for people with chronic heart failure. However, the National Service Framework for coronary heart disease, published in 2000, recommends considering the potential benefit from “palliative care services and palliation aids (e.g. home oxygen)”.
The British Thoracic Society recommends that home oxygen therapy may be helpful for people with severe chronic heart failure, though only if they also suffer from hypoxaemia, low levels of oxygen in the blood.
What are the implications?
Because the trial was underpowered, interpretation is difficult. The results provide no evidence that long-term home oxygen therapy improves quality of life for people with severe chronic heart failure. However the authors acknowledge that it is not possible to distinguish whether the lack of a detected effect is a result of the trial being underpowered or whether there is a true lack of effect. The low adherence may also have reduced the impact of therapy.
Oxygen therapy can be burdensome. It limits mobility, it can cause soreness around the nose and the equipment is noisy. The concentrator has to be fitted to the home, usually requiring some drilling through walls. The machine uses electricity, the costs of which are normally met by the NHS. Home oxygen therapy is therefore expensive to the health service and burdensome to the patient, and the results of this trial, while preliminary in nature, suggest that it is not money well spent as a treatment for heart failure. It is possible that emergency use of oxygen, from an oxygen bottle, could still be of use for severe episodes of breathlessness and might reduce hospital admissions. The authors suggest that this could be studied further.
Citation
Clark AL, Johnson M, Fairhurst C, et al. Does home oxygen therapy (HOT) in addition to standard care reduce disease severity and improve symptoms in people with chronic heart failure? A randomised trial of home oxygen therapy for patients with chronic heart failure. Health Technol Assess. 2015;19(75):1-120.
This project was funded by the National Institute for Health Research Health Technology Assessment programme (project number 06/80/01).
Bibliography
Hardinge M, Annandale J, Bourne S, et al. British Thoracic Society guidelines for home oxygen use in adults: accredited by NICE. Thorax. 2015;70 Suppl 1: i1-43.
Minnesota Living With Heart Failure Questionnaire. Technology #94019. Minneapolis (MN): University of Minnesota; 2015.
NHS. National Service Framework for Coronary Heart Disease. London: Department of Health; 2000.
NICE. Chronic heart failure. Costing report. Implementing NICE guidance. London: National Institute for Health and Care Excellence; 2010.
NICE. Chronic heart failure in adults: management. CG108. London: National Institute for Health and Care Excellence; 2010.
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