COPD: Chronic Obstructive Pulmonary Disease

What is copd?

Chronic Obstructive Pulmonary Disease (COPD) is a large group of lung diseases characterized by airflow obstruction. COPD is often associated with symptoms related to difficulty in breathing, but can be present without any symptoms. The most important and frequent conditions of COPD are chronic bronchitis and emphysema, but COPD also includes other diagnoses.

Prevalence of COPD

Chronic lower respiratory disease, primarily COPD, was the third leading cause of death in the United States in 2011.1 Beginning in 2008, COPD has surpassed stroke as the third leading cause of death in the U.S.3,4 Around 5% of the Vermont population is reported to have COPD. The prevalence of COPD increased significantly across each of the three age groups, 18­-44, 45­-64 and 65+. This was expected, as the development of COPD is slow and longer risk factor exposures are known to increase the chances of disease development, thus causing it to be primarily a disease of older people.

Causes of COPD

Between 80% and 90% of COPD is due to tobacco use. This is evident when looking at COPD diagnosis by smoking status among Vermont adults. COPD accounts for 1.5 million emergency department visits annually, and the number of visits has been on the rise since the early 1990s.5  Approximately two-thirds of patients in the emergency department with COPD symptoms are consequently admitted as inpatients.As of 2009, 11.8 million adults aged 18+ years in the United States reported having physician-diagnosed COPD, however it is commonly accepted that COPD is frequently underdiagnosed.6

    Environmental Risk Factors

    Although the primary cause of COPD is smoking, an increasing number of studies have reported associations between indoor and outdoor air pollution exposures and COPD, suggesting that environmental exposures could be driving a percentage of COPD cases.5,8, 9 

    The most prominent indoor exposures are from smoke from tobacco and the use of biomass fuels, while the most common non-occupational outdoor exposures are particulate matter (PM10 & PM2.5), ozone, and sulfur dioxide from automobiles and industrial sources.10,11 

    Studies have also shown significant associations with occupational exposures such as fumes, gases, and both inorganic and organic dusts.9, 12, 13 

    In 2003, the American Thoracic Society showed that roughly 19% of all COPD cases were attributable to occupational exposures with 31% in never-smokers.13

    Other Risk Factors & Co-Morbidities

    COPD is associated with several important comorbidities, with asthma being the most important. It has been estimated that those with active asthma were 10 times more likely to develop chronic bronchitis, and 17 times more likely to develop emphysema compared to those without asthma, after controlling for potential confounders.

    Current asthma diagnosis was the most significant risk factor for COPD, even higher than cigarette smoking.8 

    Prior respiratory infections has also been identified as a key risk factor for COPD.7

    Cardiovascular disease and COPD are strongly associated and frequently both are reported on the death certificate. One study has shown that of 45,000 patients with COPD, heart failure, myocardial infarction, and stroke are the leading causes of death14, while another found that the prevalence of all cardiovascular diseases was higher in patients with COPD resulting in higher risk of an emergency department visit and mortality.15

    References
    1. Hoyert DL, Xu JQ. Deaths: preliminary data for 2011. Natl Vital Stat Rep. 2012;61(6):1-65. Hyattsville, MD: National Center for Health Statistics.2012.
    2. Tsai CL, Clark S, Cydulka RK, Rowe BH, Camargo CA Jr. Factors associated with hospital admission among emergency department patients with chronic obstructive pulmonary disease exacerbation. Acad Emerg Med. 2007 Jan;14(1):6-14. Epub 2006 Nov 21.
    3. Kochanek KD, Xu JQ, Murphy SL, et al. Deaths: Preliminary data for 2009. National vital statistics reports; vol 59 no 4. Hyattsville, MD: National Center for Health Statistics. 2011.
    4. Miniño AM. Death in the United States, 2009. NCHS data brief, no 64. Hyattsville, MD: National Center for Health Statistics. 2011.
    5. Mannino DM, Homa DM, Akinbami LJ, Ford ES, Redd SC. Chronic obstructive pulmonary disease surveillance--United States, 1971-2000. MMWR Surveill Summ. 2002 Aug 2;51(6):1-16.
    6. Trends in COPD (Chronic Bronchitis and Emphysema): Morbidity and Mortality. American Lung Association February 2010.
    7. Dalal AA, Christensen L, Liu F, Riedel AA. Direct costs of chronic obstructive pulmonary disease among managed care patients. Int J Chron Obstruct Pulmon Dis. 2010 Oct 5;5:341-9.
    8. Salvi SS, Barnes PJ. Chronic obstructive pulmonary disease in non-smokers. Lancet. 2009 Aug 29;374(9691):733-43.
    9. Harber P, Tashkin DP, Simmons M, Crawford L, Hnizdo E, Connett J; Lung Health Study Group. Am J Respir Crit Care Med. Effect of occupational exposures on decline of lung function in early chronic obstructive pulmonary disease. 2007 Nov 15;176(10):994-1000. Epub 2007 Jul 12.
    10. Ko FW, Tam W, Wong TW, Chan DP, Tung AH, Lai CK, Hui DS.Temporal relationship between air pollutants and hospital admissions for chronic obstructive pulmonary disease in Hong Kong. Thorax. 2007 Sep;62(9):780-5. Epub 2007 Feb 20.
    11. Medina-Ramón M, Zanobetti A, Schwartz J. The effect of ozone and PM10 on hospital admissions for pneumonia and chronic obstructive pulmonary disease: a national multicity study. Am J Epidemiol. 2006 Mar 15;163(6):579-88. Epub 2006 Jan 27.
    12. Hu Y, Chen B, Yin Z, Jia L, Zhou Y, Jin T. Increased risk of chronic obstructive pulmonary diseases in coke oven workers: interaction between occupational exposure and smoking. Thorax. 2006 Apr;61(4):290-5. Epub 2006 Feb 7.
    13. Eduard W, Pearce N, Douwes J. Chronic bronchitis, COPD, and lung function in farmers: the role of biological agents. Chest. 2009 Sep;136(3):716-25. Epub 2009 Mar 24.
    14. Sidney S, Sorel M, Quesenberry CP, DeLuise C, Lanes S, Eisner MD. COPD and incident cardiovascular disease emergency department visits and mortality: Kaiser Permanente Medical Care Program. Chest. 2005;128:2068-2075.
    15. Curkendall SM, DeLuise C, Jones JK, Lanes S, Stang MR, Goehring E, She D. Cardiovascular disease in patients with chronic obstructive pulmonary disease, Saskatchewan Canada casridvascular disease in COPD patients. Ann Epidemiol. 2006;16:63-70.