Chronic obstructive pulmonary disease (COPD) has seen several changes in its assessment and treatment in recent years, reflecting advances in our understanding of this common and serious disease.
This review updates busy practitioners on the major advances, including new assessment tools and new therapies.
COMMON AND INCREASING
COPD is the third leading cause of death in the United States, behind heart disease and cancer,1 and of the top five (the others being stroke and accidents), it is the only one that increased in incidence between 2007 and 2010.2 The 11th leading cause of disability-adjusted life years worldwide in 2002, COPD is projected to become the seventh by the year 2030.3
CHARACTERIZED BY OBSTRUCTION
COPD is characterized by persistent and progressive airflow obstruction associated with chronic airway inflammation in response to noxious particles and gases. Disease of the small airways (inflammation, mucus plugging, and fibrosis) and parenchymal destruction (emphysema) limit the flow of air.
COPD is diagnosed by spirometry—specifically, a ratio of forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC) of less than 0.7 after a bronchodilator is given. The severity of airflow limitation is revealed by the FEV1 as a percent of the predicted value.
Cigarette smoking is the major cause of COPD, but the prevalence of COPD is 6.6% in people who have never smoked, and one-fourth of COPD patients in the United States have never smoked.4
GOLDEN GOALS: FEWER SYMPTOMS, LOWER RISK
The Global Initiative for Chronic Obstructive Lung Disease (GOLD) periodically issues evidence-based statements on how to prevent and treat COPD.
In its 2013 update,5 GOLD suggested two goals: improving symptoms and reducing the risk of death, exacerbations, progression of disease, and treatment-related adverse effects. The latter goal—reducing risk—is relatively new.
Exacerbations are acute inflammatory events superimposed on chronic inflammation. The inflammation is often brought on by infection6 and increases the risk of death7 and the risk of a faster decline in lung function.8
Exacerbations may characterize a phenotype of COPD. The Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) analyzed the frequency of COPD exacerbations and associated factors in 2,138 patients with COPD over a period of 3 years.9 Although patients with more severe obstruction tended to have more exacerbations, some patients appeared susceptible to exacerbations irrespective of the severity of obstruction. The best predictor of exacerbations was a history of exacerbations.
HOW DO I ASSESS A PATIENT WITH COPD ON PRESENTATION?
Markers of airflow obstruction such as the FEV1 do not correlate strongly with exertional capacity and health status in patients with COPD.10,11
The BODE index (body mass index, obstruction, dyspnea score, and exercise oximetry) takes into account the multidimensional nature of COPD. It performs better than the FEV1 in predicting the risk of death.12 The propensity for exacerbations and comorbidities further modulates outcome.
The modified British Medical Research Council (mMRC) dyspnea scale, based on work by Fletcher in 1952,13 has five grades, numbered 0 through 4:
- Grade 0—Breathless with strenuous exercise only
- Grade 1—Breathless when hurrying on level ground or walking up a slight hill
- Grade 2—Walks slower than people of the same age on level ground because of shortness of breath or has to stop when walking at own pace on level ground
- Grade 3—Stops for breath after walking about 100 yards or after a few minutes on level ground
- Grade 4—Too breathless to leave the house or breathless when dressing or undressing.
Grade 2 or higher separates symptomatic from asymptomatic COPD.
The COPD Assessment Test (CAT) (www.catestonline.org) is a proprietary questionnaire. Patients use a 6-point scale (numbered 0 though 5) to rate eight symptoms (cough, mucus production, chest tightness, shortness of breath on exertion, limitations in home activities, lack of confidence leaving the home, poor sleep, and lack of energy). A total score of 10 or higher is abnormal.
Four GOLD groups
The new GOLD guidelines (Table 1)5 define four groups of patients according to their severity of airflow obstruction, symptoms, and exacerbation history:
- Group A—fewer symptoms, low risk: Fewer symptoms (“less symptoms,” as worded in the guidelines) means a CAT score less than 10 or an mMRC grade less than 2; “low risk” means no more than one exacerbation per year and an FEV1 of at least 50%
- Group B—more symptoms, low risk: “More symptoms” means a CAT score of 10 or more or an mMRC grade of 2 or more
- Group C—fewer symptoms, high risk: “High risk” means two or more exacerbations per year or an FEV1 less than 50%
- Group D—more symptoms, high risk.
Thus, a patient with an FEV1 of 60% (moderate airflow limitation) who has had one exacerbation during the past year and a CAT score of 8 would be in group A. In contrast, a patient who has an FEV1 of 40% (severe airflow limitation), no history of exacerbations, and a CAT score of 20 would be in group D.
Updated GOLD guidelines suggest utilizing a stepwise approach to treatment, akin to asthma management guidelines, based on patient grouping.5