APRIL 15, 2001 • HOSPITAL PRACTICE
Early Diagnosis of COPD
Dr. Petty is Professor, Department of Medicine, University of Colorado Health Sciences Center, and Chairman, National Lung Health Education Program, Denver.
Chronic obstructive pulmonary disease (COPD), a spectrum of disorders that includes chronic bronchitis, asthmatic bronchitis, and emphysema, now is the fourth most common disease in the United States. In the year 2001, approximately 115,000 Americans will die of COPD. The only proven therapy known to increase the longevity of affected patients is long-term oxygen therapy.1 It is estimated that at least 800,000 patients with COPD receive home oxygen therapy at a cost that exceeds $3 billion a year.
The third National Health and Nutrition Examination Survey indicated that COPD is grossly underdiagnosed in the noninstitutionalized U. S. population.2 COPD is a smoker's disease that clusters in families. Its prevalence and severity increases with smoking intensity and age. Thus, as the U.S. population ages, the prevalence of COPD will continue to rise.
An insidious disease, COPD is characterized by accelerated loss of lung function (i.e., a two- to fourfold increase in the normal, age-related annual rate of decline in FEVi). Thus, patients with rapid declines in FEV1 are on a collision course with the development of symptomatic disease. Such patients must be identified early. Although smoker's cough and mucus hypersecretion may be present, symptoms alone are not indicative of the degree of abnormal ventilatory function. Spirometric measurements are required in the diagnosis of COPD, just as blood pressure measurements are needed during the asympto- matic stages of systemic hypertension.
The National Lung Health Education Program recommends that simple spirometry be performed in all smokers aged 45 years or older and in anyone with cough, mucus hypersecretion, dyspnea on exertion, or wheezing.3 Smoking cessation is critical in patients with significant Spirometric abnormalities. When patients with early degrees of airflow obstruction are able to stop smok- ing, a small improvement in FEV1 occurs, followed by a very slow decline over five years.4 By contrast, patients who continue to smoke experience accelerated decline.
Several pharmacologic agents are available to mitigate the symptoms of nicotine withdrawal. Nicotine gum and the nicotine patch can be obtained without a prescription. Nicotine nasal spray and the nicotine inhaler (which looks like a cigarette) require a prescription. Bupropion is a dopaminergic antidepressant that helps to alleviate nicotine craving. Nicotine replacement products and bupropion can be used alone or together in heavily addicted patients. When these products are used in conjunction with behavioral modification and a designated quit date, approximately 20% to 30% of patients can successfully quit smoking and remain abstinent.5
All patients with any degree of COPD should receive an influenza virus vaccine each fall and be vaccinated against pneumococcus. Anticholinergics and pagonistic bronchodilators are useful in symptomatic patients. The use of inhaled corticosteroids has not been shown to re- tard the rate of FEV1 decline, but these agents do reduce the frequency of symptomatic exacerbations.6 However, the symptomatic benefits need to be weighed against the possibility of long-term systemic side effects.6 Techniques of pulmonary rehabilitation are valuable in improving exercise tolerance and quality of life, but there is scant evi- dence that pulmonary rehabilitation lengthens life. New therapies that address the basic inflammatory processes of COPD are being studied.7
COPD will remain a challenge for all primary care physicians and pulmonologists in the foreseeable future. The reasons are simple. In addition to the aging population of current smokers, we are not making great progress in convincing teenagers to refrain from smoking.
1. Nocturnal Oxygen Therapy Trial Group. Continuous or nocturnal oxy- gen therapy in hypoxemic chronic obstructive lung disease: A clinical tri- al. Ann Intern Med 93:391, 1980
2. Mannino DM et al. Obstructive lung disease and low lung function in adults in the United States: Data from the National Health and Nutri- tion Examination Survey, 1988-1994. Arch Intern Med 160:1683,2000
3. Ferguson GT et al. Office spirometry for lung health assessment in adults: A consensus statement from the National Lung Health Education Program. Chest 117:1146, 2000
4. Anthonisen NR et al. Effects of smoking intervention and the use of an inhaled anticholinergic bronchodilator on the rate of decline ofFEVi. The Lung Health Study. JAMA 272:1497, 1994
5. jorenby DE et al. A controlled trial of sustained-release bupropion, a nicotine patch, or both for smoking cessation. N EngI j Med 340:685, 1999
6. Lung Health Study Research Group. Effect of inhaled triamcinolone on the decline in pulmonary function in chronic obstructive pulmonary dis- ease. N EngI j Med 343:1902, 2000
7. Barnes Pj. Chronic obstructive pulmonary disease. N EngI ] Med 343:269, 2000