Oxygen Therapy May Not Help Some COPD Patients
Long-term supplemental oxygen treatment may not provide much help to some patients who have chronic obstructive pulmonary disease (COPD), researchers say.
The group of patients studied have moderately low blood oxygen levels, and the investigators, from the Johns Hopkins University School of Medicine, concluded that the treatment made little or no change in time to death, time to first hospitalizations or significant quality of life improvements.
The findings were published in the New England Journal of Medicine. They are based on research examining oxygen treatment outcomes in 738 COPD patients with moderately low blood oxygen levels at 42 clinical centers in the United States. The study began in 2009 and ended in 2015. Patients who received supplemental oxygen over the course of the study showed no significant differences in rate of hospitalizations, time to death after diagnosis, exercise capacity or quality of life when compared to patients who did not receive supplemental oxygen.
The results of the study, believed by the investigators to be the largest of its kind to date, show that most people with moderately low blood oxygen levels do not receive the same benefits from long-term oxygen therapy as COPD patients with severely low blood oxygen levels.
“The benefits of long-term oxygen supplements for COPD patients with severe oxygen deficiency are clear,” says Robert Wise, M.D., professor of medicine in the university’s Division of Pulmonary and Critical Care Medicine and the paper’s corresponding author. “However, it’s never been established what benefits, if any, exist for patients with less severe oxygen deficiency.”
For the study, moderate oxygen deficiency was defined as having a blood oxygen saturation between 89 and 93 percent at rest, or a blood oxygen saturation below 90 percent during a six-minute walk test. A normal blood oxygen saturation level is generally defined as between 94 and 99 percent. Blood oxygen saturation levels are a measure of oxygen-carrying hemoglobin in circulating blood and a marker of lung function, and low levels are a hallmark of people with COPD.
To examine the benefits of supplemental oxygen, the researchers studied two types of COPD patients: those who suffered from moderate oxygen deficiency while resting, and those who suffered from moderate oxygen deficiency only during exercise. Some 133 patients had resting oxygen deficiency, 319 had only exercise-induced oxygen deficiency and 268 had both.
Participants in each of the two groups were randomly assigned to get supplemental oxygen or no supplemental oxygen at the start of the study, and all visited clinics annually for follow-up examinations that included oxygen levels at rest and exercise, oxygen use, respiratory symptoms and quality of life. All participants also completed telephone interviews biannually and completed mailed questionnaires regarding symptoms and health care use at four and 16 months.