A 70-year-old woman has had worsening chronic obstructive pulmonary disease (COPD) for 20 years. She asks if she would benefit from long-term supplemental oxygen therapy. Her resting arterial blood gases show an oxygen (O2) saturation of 91 percent.
Should patients with COPD and moderate hypoxemia (i.e., O2 saturation of 90 to 97 percent) receive continuous home oxygen therapy?
There is good evidence that the addition of home long-term continuous oxygen therapy for COPD increases survival rates in patients with severe hypoxemia (i.e., O2 saturation of less than 90 percent or partial pressure of arterial oxygen [PaO2] of less than 8 kPa per 60 mm Hg) but not in patients with moderate hypoxemia or nocturnal desaturation.
Continuous oxygen therapy is indicated in patients with COPD and severe hypoxemia. The Centers for Medicare and Medicaid Services (CMS), formerly known as the Health Care Financing Administration (HCFA), provides guidelines for supplemental oxygen therapy and sets the standard for nearly all adult oxygen prescriptions, whether the patient has Medicare or a managed care provider.2 According to these standards, oxygen therapy is covered for patients with a documented PaO2 of up to 55 mm Hg or a saturation of oxygen in arterial blood (SaO2) of up to 88 percent on room air at rest. Most insurers, including Medicare, will allow a prescription for home oxygen therapy for up to 99 months (or “lifetime,” according to Medicare). CMS allows oxygen therapy for patients with an SaO2 of up to 89 percent if they have a coexisting clinical condition (i.e., cor pulmonale, congestive heart failure, hematocrit of more than 56 mg per dL).
Background. Domiciliary oxygen therapy has become one of the major forms of treatment for patients with hypoxemic COPD.
Objectives. To determine the effect of domiciliary oxygen therapy on survival and quality of life in patients with COPD.
Search Strategy. The authors1 searched randomized, controlled trials (RCTs) using the Cochrane Airways Group COPD register and the search term “home OR domiciliary AND oxygen.”
Selection Criteria. RCTs of patients with hypoxemia and COPD that compared long-term domiciliary or home oxygen therapy with a control treatment were included.
Data Collection and Analysis. Data extraction was performed independently by two reviewers.
Primary Results. Five RCTs were identified. Data were aggregated from two trials of nocturnal oxygen therapy in patients with mild to moderate COPD and arterial desaturation at night. Data could not be aggregated for the three other trials because of differences in trial design and patient selection. In a study of continuous oxygen therapy versus nocturnal oxygen therapy, there was a significant improvement in mortality rates after 24 months (Peto odds ratio [OR], 0.45; 95 percent confidence interval [CI], 0.25 to 0.81). In a study comparing domiciliary oxygen therapy with no oxygen therapy, there was a significant improvement in mortality rates over five years in the group receiving oxygen therapy (Peto OR, 0.42; 95 percent CI, 0.18 to 0.98). Two studies comparing nocturnal oxygen therapy with no oxygen therapy in patients with COPD and arterial desaturation at night found no difference in mortality rates between treated and nontreated groups; this difference was noted in each trial separately and when data from the trials were aggregated. In a study of long-term oxygen therapy versus no oxygen therapy in patients with moderate hypoxemia, no effect on survival was found in up to three years of follow-up. A search conducted in January 2003 did not identify any additional studies for inclusion in the review.
Reviewers’ Conclusions. Long-term oxygen therapy improves survival rates in a select group of COPD patients with severe hypoxemia (i.e., arterial PaO2 of less than 8 kPa per 60 mm Hg). Long-term oxygen therapy does not appear to improve survival in patients with moderate hypoxemia or in those with only nocturnal arterial desaturation.
These summaries have been derived from Cochrane reviews published in the Cochrane Database of Systematic Reviews in the Cochrane Library. Their content has, as far as possible, been checked with the authors of the originalreviews, but the summaries should not be regarded as an official product of the Cochrane Collaboration; minorediting changes have been made to the text (http://www.cochrane.org).
The three modes of delivery for oxygen therapy include oxygen concentrators, compressed gas, and liquid oxygen. CMS uses a “modality neutral” method, which applies a fixed reimbursement regardless of the mode of delivery. Because survival rates are not better in patients with moderate hypoxemia, this review supports these coverage guidelines.
According to the results of this review, physicians should be vigilant in making sure that patients with COPD receive long-term oxygen therapy. One trial included in the review determined that continuous long-term oxygen therapy in patients with a PaO2 of up to 58 mm Hg reduced mortality rates over 24 months compared with nocturnal therapy (number needed to treat [NNT], 11). In another trial, patients with a PaO2 of 40 to 60 mm Hg who were treated with long-term oxygen therapy had increased five-year survival rates compared with patients who received placebo (NNT, five).
Other interventions that have proved effective in the treatment of patients with COPD also should be used, including long-acting beta2 agonists, inhaled corticosteroids, pulmonary rehabilitation, and anticholinergic agents (e.g., ipratropium [Atrovent]), depending on the staging of disease. Transplant surgery may hold promise for some patients. These treatment recommendations can be found in the comprehensive guideline from the National Heart, Blood, and Lung Institute/World Health Organization Global Initiative for Chronic Obstructive Lung Disease Workshop and two recent systematic reviews.3–6