By Harvard Medical International
Chronic Obstructive Pulmonary Disease remains vastly under-diagnosed and under-treated.
Chronic Obstructive Pulmonary Disease (COPD), a condition common among smokers, remains a major public health problem. Worldwide it kills more than 2.75 million people each year and is projected to rank fifth in 2020 in the global burden of disease. In the Middle East, where smoking is growing increasingly prevalent, the disease is thought to be on the rise too. But like elsewhere, it remains vastly under-diagnosed and under-treated.
While breathing in pollution, dust or chemicals may produce or contribute to COPD, tobacco smoking is by far the most common cause, says Christopher H. Fanta, MD, Director of the Partners Asthma Center, member of the Pulmonary and Critical Care Division at Brigham and Women's Hospital, and Associate Professor of Medicine at Harvard Medical School. About 80% to 90% of COPD cases are caused by smoking, and a smoker is 10 times more likely than a non-smoker to die of COPD, a term used to describe the combination of chronic bronchitis and emphysema.
It is possible for adults to lose up to 40% of their lung capacity without feeling the effects.
Smoking damages the lungs in two ways, explains Fanta. In chronic bronchitis, there is narrowing and clogging of the bronchi (airway tubes). In emphysema, the alveoli (air sacs) become enlarged and destroyed, which reduces the lungs' elasticity making them less "springy."
The reason so many patients with COPD go undiagnosed is that the term is not generally recognized by patients, says Fanta. Even more than that, patients can have COPD for years without noticing.
A mostly sedentary society combined with the lungs' excess breathing capacity (when healthy) make it possible for adults to lose up to 40% of their lung capacity without feeling the effects, he explains. As a result, the disease remains hidden until it is fairly advanced.
Further hindering diagnosis, few primary care physicians' offices are equipped with Spirometry - the tool used to measure breathing function. So testing is not routine. This is unfortunate, because when COPD is caught early, patients have a much better chance of quitting smoking and getting treatment at a stage of their illness that would allow them to lead a longer, healthier life.
Fanta suggests sending all patients who have smoked for 10 years or more for Spirometry.
In this In Practice, Fanta, who is also a co-author of "The Harvard Medical School Guide to Taking Control of Asthma: A Comprehensive Prevention and Treatment Plan for You and Your Family," (Free Press, January 2004), discusses current trends in treating COPD, including new tools to aid in smoking cessation, and the latest thinking on medication, oxygen supplementation, surgery, and rehabilitation.
By far, the best way to prevent COPD is to figure out how to prevent kids from taking up smoking, and helping smokers to quit, says Fanta.
Public health efforts aimed at smoking cessation can go a long way. In the U.S., for example, smoking is now banned in public buildings and restaurants. Over the past 50 years, the percentage of adults who smoke has gone from 50% of men and over 40% of women to just under 25%. Short of spearheading a widespread public health initiative, physicians can do their part by asking all patients whether they smoke and, if so, whether they are interested in quitting. If they express a desire to quit, says Fanta, there are a number of aids that can be offered that have been shown to work well.
Effective smoking cessation aids include:
• Nicotine replacement therapy
• Smoking cessation counseling programs
• Buproprion, an antidepressant approved in the US to help people quit smoking
• Varenicline, the first approved nicotinic acetylcholine receptor antagonist (and partial agonist)
Bronchodilators remain the mainstay of medical therapy for patients with COPD. These drugs, which include long-acting inhaled beta-agonists and the long-acting anticholinergic agent, tiotropium, can be taken as easily as only once or twice a day.
They relax the muscles that surround the bronchi, helping them to expand a bit. But these drugs do nothing to change the elasticity of the lung tissue and so may help the symptoms of emphysema only minimally, says Fanta.
Inhaled corticosteroid medications have also been used to treat patients with COPD, but there is some controversy as to their benefits, says Fanta. While these anti-inflammatories work well for patients with asthma, they are less effective at treating the inflammation that accompanies COPD. Their benefit has been best demonstrated for people with more advanced disease or lots of exacerbations.
Bronchodilators remain the mainstay of medical therapy for patients with COPD.
Another form of therapy combines these two approaches (long-acting beta-agonists and inhaled corticosteroids). Recently, researchers in the UK studied the combination therapy in over 6,000 patients over a three-year period. Their results were published in the Feb. 22, 2007 issue of the New England Journal of Medicine.
They found that the combination regimen reduced the number of exacerbations and improved health and breathing function as compared with placebo. The regimen also appeared to lower the death rate - though the difference was not quite statistically significant. And in a surprise finding, patients on the regimen were more likely to have pneumonia.
Despite its shortcomings, the trial is important because it represents the first time any drug therapy has been shown to make people with COPD live longer, says Fanta. "The take home point is that good medical care not only makes patients with COPD feel better and have fewer flare-ups, but also seems to make them live longer. But we're not quite sure exactly how to use these medications in an ideal way, so more research is needed."
Some patients with COPD develop chronic hypoxemia (inadequate oxygen in the blood). If these patients have the resources, they can benefit from supplemental oxygen, which not only helps them to feel better but can add many years to their lives. They need to use it all the time, but it has a dramatic impact on survival in advanced COPD, says Fanta.
While home-oxygen benefits people with advanced COPD and chronic hypoxemia, many patients with emphysema do not have chronic hypoxemia. Bronchodilators and inhaled steroids may provide only little relief for these patients. "If patients can't breathe despite these treatments," says Fanta, "they may be candidates for a dramatic new surgery introduced around 10 years ago."
This surgery, called lung volume reduction surgery (LVRS), involves removing the most damaged portions of the lungs. It appears to work well for some patients, but there are substantial risks in cutting out lung tissue, says Fanta. Some patients have died or developed respiratory failure with prolonged dependence on mechanical ventilators.
Several years ago, the surgery was put to a five-year multi-centre clinical trial called the National Emphysema Treatment Trial (NETT) which studied LVRS to treat patients with severe empysema. The result, published in the May 22, 2003 edition of the NEJM, was that on average, patients who underwent LVRS with medical therapy were more likely to function better after two years but were no more likely to live longer compared to those who got medical therapy alone. But the effects of the procedure varied widely.
Two characteristics helped predict the outcome of the surgery for individual patients. One was the distribution of emphysema (that is, whether the damage was concentrated in the upper areas of the lungs). The other was the patient's exercise capacity. Patients whose emphysema was predominantly in the upper lobes of the lung and whose exercise capacity was low after pulmonary rehabilitation but prior to surgery were more likely to survive longer and function better after LVRS compared to similar patients who received medical therapy only.
In contrast, in patients who did not have upper lobe distribution of emphysema and who had greater exercise capacity, LVRS decreased survival and failed to improve functional levels. The main takeaway is that "LVRS is new and exciting -- for certain patients," says Fanta. And perhaps equally important, the success raises the possibility that bronchoscopic lung volume reduction -- a less invasive procedure - may also be used effectively to remove the damaged portions of a patient's lungs. "There is a lot of exciting research currently being done on this approach to the treatment of emphysema," Fanta observes.
Pulmonary rehabilitation is another important strategy in treating COPD. But there is no evidence yet that it prolongs survival. "It makes patients feel better and improves their ability to exercise and their quality of life, but it doesn't help them to live longer," says Fanta.
New evidence-based guidelines from the American College of Chest Physicians (ACCP) and the American Association of Cardiovascular and Pulmonary Rehabilitation (AACVPR) recommend a comprehensive pulmonary rehabilitation program for patients with COPD, for the reasons Fanta cites, and its potential to decrease hospital stay and healthcare utilisation. The new guidelines are published in the May, 2007 issue of CHEST, the peer-reviewed journal of ACCP.
Pulmonary rehabilitation can include exercise training, education, instruction in various respiratory techniques, and psychosocial support. Research shows that pulmonary rehabilitation is appropriate for any stable patient with COPD who is disabled by respiratory symptoms. The guidelines recommend pulmonary rehabilitation programs beyond 12 weeks in duration, because they appear to produce greater benefits than shorter programs.
This article is provided courtesy of Harvard Medical International. © 2007 President and Fellows of Harvard College.