Looking at the Patient — Approaching the Problem of COPD
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《新英格兰医药杂志》
Chronic obstructive pulmonary disease (COPD) is currently the fourth leading cause of death in the United States and is expected to become the third leading cause of death by 2020. Cigarette smoking is the major risk factor, but as many as 20 percent of patients who have COPD or die from the disease are lifelong nonsmokers. Despite its importance as a public health problem, COPD is vastly underappreciated. It is underdiagnosed and, when diagnosed, commonly undertreated. The need to increase awareness about COPD is a worldwide problem and has led to a number of initiatives, including the Global Initiative for Chronic Obstructive Lung Diseases (often referred to as GOLD).1
One of the difficulties in understanding COPD is that it is not a single entity. Rather, it is a collection of conditions, many of which can be caused by cigarette smoking as well as by other factors. All these conditions share a common physiological abnormality — namely, the limitation of expiratory airflow. This unifying feature not only helps to define COPD, but has also helped to direct the development and implementation of the currently available therapies. It is clear, however, from looking at patients with COPD that this disease is not a simple problem. Like all complex disorders, COPD affects far more than a single organ system. Not surprisingly, the heterogeneous conditions that constitute COPD can have many diverse extrapulmonary effects. The famous images of the "pink puffer" and the "blue bloater," though not part of our current clinical paradigms, refuse to disappear, primarily because they, in an admirably alliterative manner, describe salient clinical observations (see Figure). These images, however, only partially reflect the heterogeneous nature of COPD. Recent studies have emphasized that patients with similar degrees of airflow limitation can have obvious and marked differences in body habitus, exercise performance, and oxygenation, all of which serves to confuse clinical classification.
Figure. Looking at the Patient with COPD.
COPD may be manifested in striking systemic features. These may vary markedly, even among patients with similar degrees of airflow limitation. The classic "blue bloater" (left) is characterized by hypoxemia, possibly with carbon dioxide retention, which may be complicated by pulmonary hypertension and signs of right-sided heart failure. The "pink puffer" (right), in contrast, is characterized by cachexia, relatively preserved blood gases, and often dyspnea even when the patient is at rest. Cough and sputum may be prominent in the blue bloater but may also be present in the pink puffer. Emphysema is often severe in the pink puffer but may also be present in the blue bloater. Thus, the two phenotypes illustrated here represent different systemic manifestations of a complex disease. Many patients with systemic manifestations of COPD do not resemble either of these patients.
The optimal approach to the diagnosis and management of COPD has remained problematic. The assessment of airflow is absolutely essential. Unfortunately, spirometry is rarely used in the routine assessment of patients with COPD — a failure that may in part reflect the fact that the forced expiratory volume in one second measures only one aspect of the patient's clinical status. The availability of easy-to-use, inexpensive equipment that provides internal quality control to ensure that the measures meet accepted standards and the introduction of billing codes permitting routine reimbursement for spirometry promise to increase greatly the use of this crucial test in generalists' offices. Unfortunately, additional information is still needed to complement the assessment of spirometry. The article by Celli and colleagues in this issue of the Journal (pages 1005–1012) helps to address this need.
These investigators developed a multistage scoring system that incorporates a spirometric measure of airflow together with an assessment of symptoms, body habitus, and exercise capacity. Variables that can be evaluated easily in any office setting were chosen intentionally, so that the index can be applied readily and simply. Having established the measures in a retrospective cohort, the investigators then prospectively validated the use of their "BODE index." (The B stands for body-mass index, O for the degree of airflow obstruction, D for dyspnea, and E for exercise capacity.) The acronym, with its obvious implications, was suggested by Gordon Snider, a physician-scientist with a career-long interest in COPD, precisely because it provides useful prognostic information. This index is desperately needed.
Without doubt, the assessment of airflow is crucial in establishing the diagnosis of COPD and, in the opinion of many experts, can often help to guide therapy. The availability of other validated measures, particularly those that integrate multiple non–airflow-related variables, is also essential. Clinicians will be faced with increasing numbers of patients with COPD. Fortunately, we will also have increasingly effective forms of therapy. The successful development and use of these treatments will require careful assessment of patients. The BODE index promises to be an important tool in this regard.
Source Information
From the University of Nebraska Medical Center, Omaha.
References
GOLD Workshop Report. Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. Bethesda, Md.: NHLBI, 2003. (Accessed February 12, 2004, at http://www.goldcopd.com.)(Stephen I. Rennard, M.D.)
One of the difficulties in understanding COPD is that it is not a single entity. Rather, it is a collection of conditions, many of which can be caused by cigarette smoking as well as by other factors. All these conditions share a common physiological abnormality — namely, the limitation of expiratory airflow. This unifying feature not only helps to define COPD, but has also helped to direct the development and implementation of the currently available therapies. It is clear, however, from looking at patients with COPD that this disease is not a simple problem. Like all complex disorders, COPD affects far more than a single organ system. Not surprisingly, the heterogeneous conditions that constitute COPD can have many diverse extrapulmonary effects. The famous images of the "pink puffer" and the "blue bloater," though not part of our current clinical paradigms, refuse to disappear, primarily because they, in an admirably alliterative manner, describe salient clinical observations (see Figure). These images, however, only partially reflect the heterogeneous nature of COPD. Recent studies have emphasized that patients with similar degrees of airflow limitation can have obvious and marked differences in body habitus, exercise performance, and oxygenation, all of which serves to confuse clinical classification.
Figure. Looking at the Patient with COPD.
COPD may be manifested in striking systemic features. These may vary markedly, even among patients with similar degrees of airflow limitation. The classic "blue bloater" (left) is characterized by hypoxemia, possibly with carbon dioxide retention, which may be complicated by pulmonary hypertension and signs of right-sided heart failure. The "pink puffer" (right), in contrast, is characterized by cachexia, relatively preserved blood gases, and often dyspnea even when the patient is at rest. Cough and sputum may be prominent in the blue bloater but may also be present in the pink puffer. Emphysema is often severe in the pink puffer but may also be present in the blue bloater. Thus, the two phenotypes illustrated here represent different systemic manifestations of a complex disease. Many patients with systemic manifestations of COPD do not resemble either of these patients.
The optimal approach to the diagnosis and management of COPD has remained problematic. The assessment of airflow is absolutely essential. Unfortunately, spirometry is rarely used in the routine assessment of patients with COPD — a failure that may in part reflect the fact that the forced expiratory volume in one second measures only one aspect of the patient's clinical status. The availability of easy-to-use, inexpensive equipment that provides internal quality control to ensure that the measures meet accepted standards and the introduction of billing codes permitting routine reimbursement for spirometry promise to increase greatly the use of this crucial test in generalists' offices. Unfortunately, additional information is still needed to complement the assessment of spirometry. The article by Celli and colleagues in this issue of the Journal (pages 1005–1012) helps to address this need.
These investigators developed a multistage scoring system that incorporates a spirometric measure of airflow together with an assessment of symptoms, body habitus, and exercise capacity. Variables that can be evaluated easily in any office setting were chosen intentionally, so that the index can be applied readily and simply. Having established the measures in a retrospective cohort, the investigators then prospectively validated the use of their "BODE index." (The B stands for body-mass index, O for the degree of airflow obstruction, D for dyspnea, and E for exercise capacity.) The acronym, with its obvious implications, was suggested by Gordon Snider, a physician-scientist with a career-long interest in COPD, precisely because it provides useful prognostic information. This index is desperately needed.
Without doubt, the assessment of airflow is crucial in establishing the diagnosis of COPD and, in the opinion of many experts, can often help to guide therapy. The availability of other validated measures, particularly those that integrate multiple non–airflow-related variables, is also essential. Clinicians will be faced with increasing numbers of patients with COPD. Fortunately, we will also have increasingly effective forms of therapy. The successful development and use of these treatments will require careful assessment of patients. The BODE index promises to be an important tool in this regard.
Source Information
From the University of Nebraska Medical Center, Omaha.
References
GOLD Workshop Report. Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. Bethesda, Md.: NHLBI, 2003. (Accessed February 12, 2004, at http://www.goldcopd.com.)(Stephen I. Rennard, M.D.)