Published in UAB Insight, Spring 2007
Underdiagnosis of Chronic Obstructive Pulmonary Disease
ABSTRACT: More smokers than previously thought may develop COPD. Early diagnosis and treatment can improve quality of life and survival.
CME OBJECTIVE: The reader will better appreciate the need to perform regular spirometry on people at risk for COPD and the need for smoking cessation counseling.
Mark T. Dransfield, MD, grants/research support: GlaxoSmithKline (GSK), Boehringer Ingelheim (BI), Roche, Almirall; honoraria: GSK, BI; William C. Bailey, MD, grants/research support: GSK, BI, Pfizer; consultant/honoraria: GSK, BI, Pfizer
Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death in the United States at a cost of $37 billion a year. More than 30 million Americans have airflow obstruction, but only 10 million carry a COPD diagnosis, and just 4 million receive treatment. Smoking is the primary risk factor for COPD, and physicians are traditionally taught that 15% to 20% of smokers develop the disease. According to a study by UAB pulmonologists Mark T. Dransfield, MD, and Chad E. Miller, MD, more than half of smokers or former smokers may have COPD.
Investigators studied patients enrolled in the National Lung Screening Trial (NLST), a National Cancer Institute-sponsored randomized trial comparing annual chest X-rays (CXR) with computed tomography (CT) scans for early detection of lung cancer. Dransfield and Miller obtained demographic and medical information and performed spirometry on 449 NLST enrollees. They used prebronchodilator criteria to classify participants according to Global Initiative for Obstructive Lung Disease (GOLD) stages and then determined the fraction that had received a COPD diagnosis and treatment. Dransfield and Miller found 236 participants (53%) had airway obstruction and 163 (36%) had at least GOLD Stage II disease. Only 34% were previously diagnosed with COPD, and 18% had received treatment for the condition. Of those with Stage III or IV disease, 67% were diagnosed and 51% had been treated. “Clearly COPD is underrecognized and undertreated in patients at risk for lung cancer,” Dransfield says, “and significant airflow obstruction occurs more frequently among smokers than previously thought. Physicians should be alert to the possibility that a majority of smokers and former smokers will develop abnormal lung function.”
Reasons for Underdiagnosis
Several factors contribute to underdiagnosis, Dransfield says, noting these include the stereotype of a COPD patient as an elderly man, a categorization that no longer applies; the increasing number of women dying from the disease (COPD deaths among women now outnumber those of men); and the decreasing age of patients diagnosed with COPD (more than half are younger than 65 years).
Furthermore, many individuals do not seek medical help until they have lost more than 50% of their lung function. Initial symptoms may not affect daily activities, and people may attribute minor symptoms to aging. As pulmonary functioning declines over time, people adjust by limiting physical activity.
Spirometry Is Key
Diagnosis Of COPD
Exposure to risk factors
Tobacco
Occupational pollutants
Indoor/outdoor pollution
Symptoms
Cough
Sputum production
Dyspnea
Confirmation of airflow obstruction on spirometer
FEV1/FVC <0.70 defines obstruction; value of FEV1 represented as percentage of predicted (age, sex, height) defines severity, ie, GOLD Stage III (severe) <30% predicted
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Diagnosis of COPD in the primary care setting requires spirometry. A spirometer provides more sensitive and accurate measures at lower flow rates than peak flow meters, and it predicts rapid declines in lung function. Nevertheless, a 2006 analysis concluded primary care physicians use spirometers inconsistently, and a 2005 study found while 66% of primary care physicians owned a spirometer, many did not use it: 41% were unsure of the impact on care, 38% were unfamiliar with the test, and 34% had not received training in interpreting spirometric findings (Respir Care. 2005;50:1639-1648) and (Chest. 2006;129:1509-1515).
“If the patient is a current or former smoker [10 packs a year or more] and older than 40 years, clinicians should test breathing at least once. Airflow obstruction on spirometry also predicts death from both lung cancer and cardiovascular disease independent of smoking history,” Dransfield says. Diagnosis of COPD is based on three spirometer measures: forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and their ratio (FEV1/FVC).
Early diagnosis and treatment can prevent or delay the onset of airflow limitation or reduce its progression. “Some physicians may question the utility of such testing when none of the existing COPD medications have been proven to reduce long-term decline in lung function,” says Dransfield, “but we can prescribe treatments that will help patients feel better and improve their quality of life.” Furthermore, preliminary results from the Towards a Revolution in COPD Health study indicate that Seretide/Advair (salmeterol/fluticasone propionate) reduce mortality by 17% and the rate of exacerbations by 25% compared with placebo (Eur Respir J. 2004;24:206-210).
Smoking Cessation
Smoking is the primary risk factor for COPD, causing approximately 80% to 90% of COPD deaths. Studies confirm smoking cessation preserves lung function and decreases mortality (Ann Intern Med. 2005;142:233-239). The multicenter Lung Health Study randomized 5887 smokers aged 35 to 60 years with spirometric evidence of airflow obstruction to an intensive smoking intervention or to usual care. Results showed participants in the intervention group exhibited significantly smaller declines in FEV1. After 11-year and 14.5-year follow-up, those who continued to smoke had more severe declines in lung function and increased mortality (Ann Intern Med. 2005;142[4]:233-239).
“Clinicians must continue to counsel patients aggressively about smoking cessation,” says pulmonologist William C. Bailey, MD. “Patients who want to quit smoking achieve greater success with their physician’s support.” Research indicates that spending as little as 5 minutes advising patients to stop smoking makes an impression. (Treating Tobacco and Use and Dependence. Washington DC: US Dept of Health and Human Services; June 2000).
“Physicians can provide encouragement, stress the significant benefits of smoking cessation, and offer some of the newer, more effective treatments, such as varenicline, which in several studies reduced the urge to smoke and decreased the pleasure of smoking compared with placebo,” Bailey says.
For more information:
Dr. Mark Dransfield
Dr. William Bailey
1.800.UAB.MIST
mist@uabmc.edu