Cochrane for Clinicians

Putting Evidence into Practice

Home Oxygen Therapy for Treatment of Patients with Chronic Obstructive Pulmonary Disease

R. EUGENE BAILEY, M.D., State University of New York Upstate Medical University, Syracuse, New York

This clinical content conforms to AAFP criteria for evidence-based continuing medical education (EB CME). EB CME is clinical content presented with practice recommendations supported by evidence that has been systematically reviewed by an AAFP-approved source. The practice recommendations in this activity are available online at http://www.cochrane.org/cochrane/revabstr/AB001744.htm.

The Cochrane Abstract below is a summary of a review from the Cochrane Library. It is accompanied by an interpretation that will help clinicians put evidence into practice. R. Eugene Bailey, M.D., presents a clinical scenario and question based on the Cochrane Abstract, along with the evidence-based answer and a full critique of the abstract.

Clinical Scenario

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.

Clinical Question

Should patients with COPD and moderate hypoxemia (i.e., O2 saturation of 90 to 97 percent) receive continuous home oxygen therapy?

Evidence-Based Answer

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.

Cochrane Abstract 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 original reviews, but the summaries should not be regarded as an official product of the Cochrane Collaboration; minor editing changes have been made to the text (www.cochrane.org).

Practice Pointers

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).

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

The Author

R. Eugene Bailey, M.D., is assistant professor of family medicine at State University of New York Upstate Medical University, Syracuse.

Address correspondence to R. Eugene Bailey, M.D., Center for Evidence-Based Practice, Department of Family Medicine, State University of New York Upstate Medical University, 475 Irving Ave., Suite 200, Syracuse, NY 13210 (e-mail: baileye@upstate.edu). Reprints are not available from the author.

REFERENCES

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Cochrane Briefs

Effect of Exercise Intensity on Osteoarthritis

Clinical Question

Does the intensity of therapeutic exercise for osteoarthritis matter?

Evidence-Based Answer

Although land-based exercise improves physical function, there is no evidence that high-intensity cycling offers benefits over low-intensity cycling for patients with osteoarthritis of the knee.

Practice Pointers

An earlier Cochrane review1 (last updated in 2001) of 17 studies with 2,562 participants found that group and individual exercise were effective in reducing pain (standardized mean difference [SMD], 0.39; 95 percent confidence interval [CI], 0.30 to 0.47) and improving function (SMD 0.31; 95 percent CI, 0.23 to 0.39).

Brosseau and colleagues reviewed the literature to determine whether the intensity of exercise had an effect on pain reduction. The authors identified only three studies in which adults with osteoarthritis who were assigned to different intensities of exercise were followed. One study did not report statistical data, and one had a dropout rate of more than 20 percent, leaving only a single, randomized, moderate-quality study2 for review.

Adults with osteoarthritis of the knee were assigned to low-intensity (40 percent of heart rate reserve) or high-intensity (70 percent of heart rate reserve) stationary cycling. They had three one-hour sessions per week for 10 weeks. At the end of the study period, improvement in pain and functional capacity was similar between the groups.

MARK H. EBELL, M.D., M.S.

Brosseau L, et al. Intensity of exercise for the treatment of osteoarthritis. Cochrane Database Syst Rev 2003;3:CD004259.

REFERENCES

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Intensive Management of Gestational Diabetes

Clinical Question

Does intensive management of gestational diabetes improve outcomes?

Evidence-Based Answer

There is not enough evidence to support dietary or drug treatment in patients with gestational diabetes.

Practice Pointers

Gestational diabetes and impaired glucose tolerance are associated with macrosomia and may be associated with increased risk for cesarean delivery, shoulder dystocia, and birth trauma. Although preexisting diabetes has been shown to increase the risk of poor perinatal outcomes, it is not clear that data relating to preexisting diabetes can be extrapolated to patients with gestational diabetes.

Tuffnell and colleagues searched the Cochrane Pregnancy and Childbirth Group trials register, the Cochrane Central Register of Controlled Trials, and bibliographies of relevant articles. They identified three studies of 223 women with impaired glucose tolerance; none of these studies was a randomized controlled trial comparing management strategies. Treatment of women with impaired glucose tolerance did not offer a statistically significant benefit over nontreatment in terms of abdominal operative delivery rates, neonatal intensive care admissions, or reduction in birth weight. Treatment may be associated with a reduced incidence of neonatal hypoglycemia. The trials had wide confidence intervals and methodologic shortcomings. The small number of patients studied meant that a small but clinically meaningful benefit may have been missed.

In the face of limited and inconsistent research, the American College of Obstetricians and Gynecologists (ACOG) continues to recommend universal screening for gestational diabetes.1 It recommends that insulin therapy be considered in patients for whom nutritional therapy does not result in a fasting glucose level of less than 95 mg per dL (5.3 mmol per L), a one-hour postprandial glucose level of less than 130 to 140 mg per dL (7.2 to 7.8 mmol per L), or a two-hour postprandial glucose level of less than 120 mg per dL (6.7 mmol per L). ACOG also recommends that physicians consider elective cesarean delivery for women with gestational diabetes and an estimated fetal weight greater than 4,500 g (9 lb, 15 oz). ACOG does not make a recommendation for or against calorie restriction in obese women with gestational diabetes.

Intensive management of gestational diabetes is time-consuming and resource-intensive. Overall, evidence is insufficient to support therapy for gestational diabetes. However, universal screening is the standard of care in most communities. When faced with abnormal results, most family physicians will opt to follow the consensus opinion of our specialist colleagues.

CLARISSA KRIPKE, M.D.

Tuffnell DJ, et al. Treatments for gestational diabetes and impaired glucose tolerance in pregnancy. Cochrane Database Syst Rev 2003;3:CD003395.

REFERENCE

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