COPD

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Contents

Introduction

Chronic Obstructive Pulmonary Disease (COPD) is a progressive lung disease that makes it hard to breathe. There are two main forms of COPD: 1) chronic bronchitis, which causes long-term swelling and a large amount of mucus in the main airways in the lungs, and 2) emphysema, a lung disease that destroys the air sacs in the lungs. Most people with COPD have symptoms of both. Smoking is the leading cause of COPD.

Economic analyses have shown that over 70 % of COPD-related health care expenditures result from emergency room visits and hospital care for exacerbations. This translates into > $10 billion annually in the US. In Japan, a 2001 study showed that $18 billion was spent on combined doctor visits and hospital treatments for COPD. Early identification of an exacerbation and prompt treatment improves recovery time, reduces risks of emergency hospitalisation, and is associated with better health-related quality of life. Thus, strategies for early detection of exacerbations leading to early treatment in the outpatient setting have potential substantial clinical and economic benefit.

International Aspects

COPD afflicts more than 15 million Americans, results in more than 15 million physician office visits each year, and causes approximately 150 million days of disability per year.[1] The total direct cost of medical care related to COPD is approximately $15 billion per year.[2] Similar incidence is observed in Europe and Japan. Studies show that in Japan, roughly 8.5% of people over 40 (13.1% for men, 4.4% for women) suffer from COPD, with 5.3 million people likely to get it. Of those, it is estimated that only 5% will get themselves checked for COPD. Worldwide 80 million people suffer from moderate to severe COPD and 3 million died due to it in 2005. Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death, and is projected to rank fifth in 2020 in worldwide burden of disease.


Interventions and Challenges

COPD is a steadily progressive, debilitating disease for which existing medical therapies are largely ineffective. Clinically, patients experience stable periods punctuated by exacerbations. Exacerbations are commonly defined to be episodes of increased dyspnea, cough, and change in amount and character of sputum, resulting in a change in medical therapy. Exacerbations are thought to be due to infection or environmental exposure, leading to airway inflammation. The frequency of exacerbations has been shown to be an important determinant of health-related quality of life (HRQL) in COPD and contributes to long-term decline in lung function.[3]

Early detection and treatment of an exacerbation in the outpatient setting is important to prevent worsening of clinical status and need for emergency room care or hospital admission. Available preventative therapies to reduce exacerbation frequency, such as influenza vaccination, smoking cessation, pulmonary rehabilitation, and long-term oxygen therapy, have been found to have only a relatively small effect.[4] Early treatment is associated with faster recovery, better HRQL, and lower risks of emergency hospitalization. Therefore, early identification of exacerbations would improve the timing of physician consultation, reduce exacerbation severity and disease progression, and reduce the burden of inpatient treatment of exacerbations on healthcare services.

Demonstration of airflow limitation is essential for the diagnosis of COPD. Decline in forced expiratory volume in 1 sec (FEV1) over time has been used as the ‘gold standard’ measure of disease progression in COPD. However, patients with COPD have systemic manifestations that are not reflected by the FEV1. The FEV1 correlates weakly with the degree of dyspnea.[5] Prospective, observational studies of patients with COPD have found that the degree of dyspnea and health status scores are more accurate predictors of the risk of death than is the FEV1.[6] Standard pulmonary function testing provides information on functional lung capacity at rest but limited information on ventilatory requirements or functional performance during physical activity. It is often necessary to quantify the degree of exercise intolerance experienced by the patient with COPD. Importantly, it has been shown that lung function does not decline at the onset of an exacerbation.[7] The first signs of exacerbation are deteriorations in the symptoms of dyspnea, sore throat, cough, and symptoms of a common cold, but not lung function.[8] “Alternative measures are needed that better reflect the clinical status of patients with COPD and allow detection of clinically important responses to therapies”[9] states the Global Initiative for Chronic Obstructive Lung Disease executive summary report.


Related Interventions in CAPSIL:


Enabling Technologies

Research

Numerous studies are ongoing in the US, Europe and Japan to assess interventions and patient status monitoring methodologies. NIH recently organized a workshop to identify areas in need for research to identify better interventions and monitoring methodologies in COPD and has made a large effort to increase awareness of general public of research performed in this and other major areas of work of NIH. Additionally, in Japan many private organizations are conducting research into COPD, such as this this joint project with the Japan Anti-Tuberculosis Association and other COPD related groups.


Commercial

COPD management is largely based on pharmacological interventions. From a commercial standpoint, this is a market of significant size. The use of combined inhaled corticosteroid and long-acting beta-agonist is a major part of COPD management. Long-acting muscarinic antagonist therapy has also been a major area of research by pharmaceutical companies.

Spirometry is a key component of the tools available to clinicians to assess lung function in patients with COPD. Numerous products are available to gather such measures. Extensive literature is available that addresses the use of [1] spirometry in COPD.Pulse oxymetry is also commonly used in COPD management often in combination with oxygen therapy.


Gaps

There is a need for early identification of COPD exacerbations. Lung function measures - such as FEV1 - are inadequate in describing the COPD disease state. Exercise capacity is an important indicator of COPD status, but current methods of measuring exercise capacity are limited by their assessment of the patient at a single point in time in a controlled laboratory environment and focus on lower extremity exercise. Measurement of exercise in the home and outdoor environments may potentially provide an integrative, accurate and sensitive measure of COPD status (stable versus exacerbation).[10][11][12]


Future Vision

Unobtrusive system of miniature sensors could be utilized for the detection of physical activities and measurement of associated physiological responses in oxygen saturation, heart rate, and respiratory rate for early detection of exacerbations in patients with COPD. Compared to healthy subjects, physical activity is significantly reduced in patients with moderate to severe COPD. Furthermore, among persons with COPD, higher levels of exercise capacity and physical activity are associated with better outcomes and survival.

In parallel with the development of wearable systems, it is necessary to implement data analysis procedures to identify physical activities and assess associated physiological responses. These methodologies would have to be tested in COPD patients during exacerbation episodes to study whether it is possible to achieve early detection of an exacerbation. Further, associations should be sought between measures of physical activity and physiological responses and existing laboratory-based, episodic measures of clinical status to explore the hypothesis that physical activity is a biomarker of COPD status.


Related Enabling Technologies in CAPSIL:


References

  1. ↑ Croxton TL, Weinmann GG, Senior RM, Wise RA, Crapo JD, Buist AS, “Clinical research in chronic obstructive pulmonary disease: needs and opportunities”, Am J Respir Crit Care Med, 167(8): 1142-1149, 2003.
  2. ↑ Sullivan SD, Ramsey SD, Lee TA, “The Economic Burden of COPD”, Chest, 117: 5S–9S, 2000.
  3. ↑ Donaldson GC, Seemungal TAR, Bhowmik A, Wedzicha JA. Relationship between exacerbation frequency and lung function decline in chronic obstructive pulmonary disease. Thorax 57:847-852, 2002.
  4. ↑ Garcia-Aymerich J, Barreiro E, Farrero E, Marrades RM, Morera J, Anto JM, and the EFRAM Investigators. Patients hospitalized for COPD have a high prevalence of modifiable risk factors for exacerbation (EFRAM study). Eur Respir J 16:1037-1042, 2000.
  5. ↑ Mahler DA, Weinberg DH, Wells CK, Feinstein AR, “The measurement of dyspnea. Contents, interobserver agreement, and physiologic correlates of two new clinical indexes”, Chest, 85(6): 751-758, Jun 1984.
  6. ↑ Domingo-Salvany A, Lamarca R, Ferrer M, Garcia-Aymerich J, Alonso J, Felez M, Khalaf A, Marrades RM, Monso E, Serra-Batlles J, Anto JM, “Health-related quality of life and mortality in male patients with chronic obstructive pulmonary disease”, Am J Respir Crit Care Med,166(5):680-685, Sept 2002.
  7. ↑ Seemungal TAR, Donaldson GC, Paul EA, Bestall JC, Jeffries DJ, Wedzicha JA. Effect of exacerbation on quality of life in patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med 157:1418-1422, 1998.
  8. ↑ Seemungal TAR, Donaldson GC, Bhowmik A, Jeffries DJ, Wedzicha JA. Time course and recovery of exacerbations in patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med 161:1608-1613, 2000.
  9. ↑ Connors AF, Dawson NV, Thomas C, et al. Outsomes following acute exacerbations of severe chronic obstructive lung disease. Am J Respir Crit Care Med 154:959-967, 1996.
  10. ↑ Hecht A, Ma S, Porszasz J, Casaburi R, COPD Clinical Research Network. Methodology for using long-term accelerometry monitoring to describe daily activity patterns in COPD. COPD. 6(2):121-9, 2009.
  11. ↑ Patel SA, Benzo RP, Slivka WA, Sciurba FC. Activity monitoring and energy expenditure in COPD patients: a validation study. COPD. 4(2):107-12, 2007.
  12. ↑ Coronado M, Janssens JP, de Muralt B, Terrier P, Schutz Y, Fitting JW. Walking activity measured by accelerometry during respiratory rehabilitation. J Cardiopulm Rehabil. 23(5):357-64, 2003.


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