What are the short- and long-term effects of maintenance drug treatment?
|Inhaled anticholinergic drugs|
|Inhaled beta2 agonists|
|Inhaled anticholinergics plus beta2 agonists (more effective than either alone)|
|Unlikely to be beneficial|
|Likely to be beneficial|
|Domiciliary oxygen (in people with hypoxemia)|
|Inhaled beta2 agonists|
|Unlikely to be beneficial|
|Inhaled anticholinergic drugs (no effect on decline)|
|Inhaled corticosteroids (no effect on decline)|
|To be covered in future updates of Clinical Evidence|
|Acute exacerbations of chronic obstructive pulmonary disease|
|Vaccination against influenza and pneumococcus|
|Programs to stop smoking|
|Definition||Chronic obstructive pulmonary disease (COPD) is airflow obstruction caused by chronic bron-chitis or emphysema. Emphysema is abnormal permanent enlargement of the air spaces distal to the terminal bronchioles, accompanied by destruction of their walls and without obvious fibrosis. Chronic bronchitis is chronic cough or mucus production for at least three months in at least two successive years when other causes of chronic cough have been excluded.1|
|Incidence/Prevalence||COPD mainly affects middle-aged and elderly people. It is one of the leading causes of morbidity and mortality worldwide. In the United States, it affects about 14 million people and is the fourth leading cause of death. Morbidity and mortality are rising. Estimated prevalence in the United States has risen by 41 percent since 1982, and age-adjusted death rates rose by 71 percent between 1966 and 1985. All-cause age-adjusted mortality declined over the same period by 22 percent, and mortality from cardiovascular diseases declined by 45 percent.1 In the United Kingdom, physician-diagnosed prevalence was 2 percent in men and 1 percent in women between 1990 and 1997.2|
|Etiology/Risk Factors||COPD is largely preventable. The main cause is exposure to cigarette smoke. COPD is rare in lifetime non- smokers (estimated incidence 5 percent in three large representative U.S. surveys from 1971 to 1984), in whom exposure to environmental tobacco smoke will explain at least some diseases.3,4 Other proposed causes include airway hyperresponsiveness, air pollution, and allergy.5–7|
|Prognosis||Airway obstruction is usually progressive in those who continue to smoke, resulting in early disability and shortened survival. Smoking cessation reverts the rate of decline in lung function to that of nonsmokers.8 Many people will need medication for the rest of their lives, with increased doses and additional drugs during exacerbations.|
|Clinical Aims||To alleviate symptoms, to prevent exacerbations, to preserve optimal lung function, and to improve activities of daily living, quality of life, and survival.9|
|Clinical Outcomes||Short- and long-term changes in lung function, including changes in forced expiratory volume in one second (FEV1); exercise tolerance; peak expiratory flow rate; frequency, severity, and duration of exacerbations; symptom scores for dyspnea; quality of life; and survival.|
|Evidence-Based Medicine Findings|
|SEARCH DATE: CLINICAL EVIDENCE UPDATE SEARCH AND APPRAISAL JUNE 2001|
This review deals only with treatment of stable COPD and not with treatment of acute exacerbations. Because we were interested in the maintenance treatment of stable COPD, we did not include single-dose or single-day cumulative dose response trials. Where randomized controlled trials (RCTs) were found, no systematic search for observational studies was performed.
RCTs using a range of methods in people with COPD have found that anticholinergic drugs versus placebo improve FEV1 in the short term. One large RCT found that adding a long-term anticholinergic drug to a smoking cessation program had no significant impact on decline in FEV1.
Inhaled Beta2 Agonists
Short-term RCTs found that short- and long-acting inhaled beta2 agonists versus placebo significantly improved FEV1 and symptoms.
Beta2 Agonists Plus Anticholinergics
RCTs found that combining a beta2 agonist with an anticholinergic drug provided small additional bronchodilation compared with either drug alone.
Inhaled Beta2 Agonists vs. Anticholinergics
We found conflicting evidence from RCTs on the effects of inhaled beta2 agonists versus anticholinergics.
We found limited evidence from small RCTs of a small bronchodilatory effect of theophyllines in people with COPD. Adverse effects are frequent.
One systematic review of short-term RCTs has found that corticosteroid versus placebo significantly improves lung function. We found no RCT of the effects of long-term treatment on lung function. We found evidence of potentially serious adverse effects.
RCTs found no evidence of benefit with short-term inhaled corticosteroids. Large RCTs lasting at least six months have found that inhaled steroids increase FEV1 during the first three to six months of use, but they found no subsequent effect on decline in lung function. One RCT also found that inhaled steroids versus placebo reduced the frequency of exacerbations and the rate of deterioration in quality of life.
Oral vs. Inhaled Steroids
Two RCTs found limited evidence suggesting that oral prednisolone was more effective than inhaled beclomethasone in people with mild to moderate COPD; one small RCT found no significant difference in response between treatments.
Systematic reviews have found that long-term treatment with mucolytics versus placebo significantly reduces the frequency and duration of exacerbations.
We found no RCTs of antibiotics in long-term treatment of stable COPD.
We found limited evidence that domiciliary oxygen treatment improved survival in people with COPD and hypoxemia. One RCT found that continuous treatment was more effective than nocturnal treatment.
One RCT found no significant difference between alpha1-antitrypsin versus placebo in the decline in FEV1 in people with alpha1-antitrypsin deficiency and moderate emphysema.
We found no RCTs of deoxyribonuclease (DNase) in people with COPD.