Practice changing results are presented at the European Respiratory Congress in Vienna for patients with severe hypoxemia.
Swedish research published in the NEJM and presented at the 2024 European Respiratory Society Congress in Vienna this month has found that 15 hours of oxygen is just as good as 24 hours.
“The general recommendation until now has always been that if you prescribe home oxygen, you should use at least 15 hours per day, but preferably 24 hours per day,” senior author Dr Josefin Sundh told conference delegates.
“Our finding support that there is no disadvantage of using oxygen for 15 hours a day compared with 24 hours per day with respect for the risk of hospitalisation or death or patient reported outcomes.
“And the clinical implication of this is that you could use treatment free intervals up to nine hours per day to reduce the limitations and side effects of using home oxygen without changing the prognosis.”
The Swedish Registry-Based Treatment Duration and Mortality in Long-Term Oxygen Therapy (REDOX) trial was the first RCT since the 1970s examining long-term oxygen therapy in patients with severe hypoxemia.
It involved 241 adults, mostly with COPD (71%), who had either severe hypoxemia at rest with a PaO2 lower than 55 mm Hg, or an Spo2 lower than 88% while breathing ambient air, or a PaO2 lower than 60 mm Hg while breathing ambient air and with either heart failure or polycythaemia. They were aged between 69 and 82 years; 59% were female, and 96% of participants completed the trial.
One group, 124 patients, was randomly assigned to 15 hours of supplemental oxygen therapy a day with the nine off-hours to be taken in the daytime.
“We informed every patient that was allocated to the 15-hour arm to always use oxygen during the night, because we think that’s the explanation to why it works, that it’s more important during the night. Then the remaining hours differed. Some used during activity, and some just in the connection to the night,” said Dr Sundh.
The other 117 patients had 24-hour therapy.
All participants were given ordinary low flow oxygen, at a flow rate aimed at achieving a PaO2 greater than 60 mm Hg or an SpO2 greater than 90%. There were no significant differences between the groups for comorbidities, sex, age, use of home ventilation devices or other possible relevant factors.
Data regarding hospitalisations and death was taken from the Swedish national registry and information about adherence, breathlessness, fatigue, health status, physical activity and cognitive status outcomes was self-reported.
The study found no difference in the primary outcome – a combination of hospitalisation and death, both from any cause – after a year. Both groups had a hospitalisation rate of 57%. Mortality was 32% in the 24-hour group and 27% in the 15-hour group.
There was also no inferiority in the 15-hour group in patient reported outcomes.
“There will always be patients that want to have 24 hours per day, because they also have some kind of subjective effect, but the important messages that you’re allowed to go down,” said Dr Sundh.
The results have been published in the New England Journal of Medicine, accompanied by an editorial which points out that being able to leave oxygen equipment behind for a few hours would make some difference for patients, who would often rather endure hypoxia than agree to a treatment that made them “look sick”, where they could trip over tubing and fall, that they needed help to carry unless they could afford the smaller, more expensive units, and that caused worry about not having sufficient oxygen to cover their needs if they were away from home for any length of time.
“The current results should reassure patients and clinicians that such a difference would probably be quite small. Added to the lack of an apparent difference in patient-reported functional outcomes, the results provide peace of mind that we can lessen the burden of long-term oxygen therapy — at least somewhat,” said the commentary.
One of the aspects of the trial remarked upon by an Australian delegate at the conference was the high level of adherence to the protocol by trial participants – 96% of participants completed the trial. Patients in the 24-hour group reported a median of 23 hours of use per day three months into the trial, and 24 hours at 12 months (in both cases the range was 21-24 hours). In the 15-hour group the median was 15 hours at three months (range of 15-17 hours) and at 12 months (15-16 hours).
The data was “much, much, much higher than we see in other studies,” she said. “Could you comment on why you think Swedish patients are more adherent, or is it a reporting aspect?”
“We have a very good system with oxygen nurses and registration in the oxygen registry, and good organisation around it,” Dr Sundh replied.
Recruitment had taken a long time, she added. “Maybe it’s the most dedicated patients that were involved in the study, I don’t know. But we ensured that they didn’t answer just to please us, because we could not see the results of the patient questionnaires. So we believe it’s correct.”
