Pulmonary Disorders: COPD
COPD and Law Enforcement Fitness-for-Duty Assessment
Chronic obstructive pulmonary (or lung) disease (COPD) is an entity with which most clinicians caring for adult patients have some familiarity. However, it may be helpful to provide a brief commentary here regarding some of the specifics and nuances regarding this disorder.
The definition and diagnostic criteria for COPD have evolved and continue to evolve as understanding of the pathophysiology, causation and epidemiology has advanced. Two international initiatives focus on promulgating guidance for improved understanding and care. The American Thoracic Society (ATS) and the European Respiratory Society (ERS) have jointly published guidelines for evaluation and management of COPD. The latest version was published in 2011 in conjunction with the American College of Physicians (ACP) and the American College of Chest Physicians (ACCP).2 The Global Initiative for Chronic Obstructive Lung Disease (GOLD), an initiative formed jointly by the U.S. National Heart Lung and Blood Institute and the World Health Organization, has also published guidelines for diagnosis and management with a major update in 2011 in which assessment of exacerbation history and effect of COPD on life quality were proposed as a basis for classification of severity. However, this model was found to be lacking and was, eventually combined with spirometric assessment to create a 2-dimensional classification system (see Appendix B). Yearly updates have added various modifications and updates in therapeutic and public health recommendations without changing the 2-dimensional classification scheme.1,3,4
Both sets of guidelines refer to COPD as a disorder involving persistent respiratory symptoms and airflow restriction not reversible by short-acting bronchodilators.2,3 These two sets of guidelines have some differences in approach to both definition and recommendations. GOLD characterizes COPD as being represented by “persistent respiratory symptoms and airflow limitation that is…caused by a mixture of small airways disease (obstructive bronchiolitis) and parenchymal destruction (emphysema), the relative contributions of which vary from person to person”3
The ATS, et al. group characterize COPD as a “slowly progressive disease involving the airways or pulmonary parenchyma (or both) that results in airflow obstruction.” They have recommended diagnosing COPD in persons “with symptoms of COPD” who are confirmed to have airway restrictions determined by spirometry.2 Both groups use a spirometry-determined value of <0.7 for the FEV1/FVC ratio as the basis for their diagnostic criterion of airway obstruction.
The following discussion in this and following appendices relies largely on these two publications and the sections of Up to Date on COPD, consulted most recently in February 2019, which references heavily the two other documents. For this reason, unless cited otherwise, statements of fact are associated with these sources.
Both the symptoms and pathological changes often evolve at different rates. Chronic inflammation leads to structural changes with associated narrowing of small airways and destruction of lung parenchyma and subsequent loss of alveolar attachments to small airways and decrease in elastic recoil of the lung tissue. These changes result in collapse of small airways during expiration. There is also a decrease in the number of small airways. Muco-ciliary dysfunction is another characteristic.
GOLD does not use the terms “emphysema” and “chronic bronchitis” in its definition of COPD. It argues that emphysema, the destruction of alveoli, describes a pathological finding and not a clinical condition and represents only one of several structural abnormalities seen in COPD. It also argues that chronic bronchitis, when defined as cough and sputum production for at least 3 months in 2 consecutive years, is present in a minority of persons with COPD, noting that, when alternative definitions of chronic bronchitis are used or older populations with more smoke or occupational inhalant exposure are evaluated, a higher incidence of “chronic bronchitis” is found. Additionally, GOLD notes that chronic respiratory symptoms (see Table 1) may be associated with acute respiratory decompensations in either bronchospasm or infection and may precede quantifiable airflow obstruction.3
Table 1: GOLD COPD Symptoms
- Chronic and progressive dyspnea
- Sputum production
- Wheezing and chest tightness
- Others – including weight loss, anorexia, syncope, rib fractures, ankle swelling, depression, anxiety more typically found in association with more advanced COPD
Although cigarette smoking is recognized as the most important environmental risk factor for developing COPD, other environmental exposures, genetics and possible other developmental factors are known to have a role in both presence and severity of COPD. Several epidemiological studies have demonstrated an elevated risk for persons with asthma to develop COPD, even after adjusting for smoking.5,6,7 Additionally, a syndrome of a combination of COPD and asthma has been discussed in the literature, mostly in terms of developing diagnostic schema to aid clinicians with treatment decisions.
GOLD invokes two pathways to COPD diagnosis, one symptom-based and one risk factor-based, though they may be combined. In both cases the diagnosis is finalized by the spirometry findings since symptoms such as cough, sputum production and dyspnea may precede spirometric changes by many years. GOLD recommends screening any individuals over 40 years old who have either symptoms or risk factors suggestive of COPD. Both guide-lines recommend performing spirometry only on persons with symptoms or risk factors (see Appendix B for in-depth discussion of GOLD classification criteria).
COPD is also frequently associated with other disease processes such as cardiovascular disease, mostly as a result of the common association with cigarette smoking.
COPD Exacerbation Risk
Risk of exacerbations, usually characterized as bronchospasm with or without increase in mucus production, is, probably, the most important issue of concern in evaluation of LEOs with respect to risk of sudden impairment of being able to safely and effectively perform essential job functions. Both GOLD and the ATS/ERS guidelines report the risk of exacerbations to be based on an individual’s prior history of exacerbations in terms of both frequency and severity.
Exacerbations, whether in the form of bronchospasm, worsened bronchitis or a combination are often more insidious in onset than those of asthma since they are often not as closely linked to environmental factors. They may be associated with respiratory compromise that leads to decreased ability to perform physically strenuous activities. Exacerbations are classed as mild, moderate or severe (see Table 2):
Table 2: COPD Exacerbation Classification3
Requires only treatment with a short-acting bronchodilator
Requires antibiotics and/or oral corticosteroids in addition to a short-acting bronchodilator
Associated with hospitalization or emergency department treatment
These categorizations are not precise since, for example, the decision to visit an emergency department varies with many patient-dependent factors that are not biological changes associated with the disease process. Additionally, as critical evaluations of the GOLD report have noted, COPD is extremely variable from person to person, making the clinical responses of physicians to individual patients also variable. This would manifest in this setting that the decision to prescribe antibiotics or oral corticosteroids is based on individualized physician/patient criteria, making generalization difficult.
Predictors of exacerbations have been studied in at least one large population cohort, revealing the most highly predictive factor is the history of prior exacerbations.8 Additionally, as severity of disease increased in the GOLD scoring system, frequency of exacerbations also increased (Odds ratio 4.30 (95% confidence interval 3.58–5.17). As noted above, persons may have symptoms related to pulmonary dysfunction, including exacerbations, without meeting the critical diagnostic criterion of an FEV1/FVC ratio of <0.7.
Additional factors associated with increased risk for exacerbations included >5% lung involvement with emphysema (as determined on chest CT), female sex, gastro-esophageal reflux or heartburn, wheezing or asthma and osteoporosis. Odds ratios ranged from 1.42 for female sex to 1.74 for osteoporosis. Review of data from a large cohort study identified a significant variability year-over-year in exacerbations, even in persons with more severe COPD (GOLD spirometric stages 3 and 4).9 This report emphasizes the necessity for individualized assessment of LEOs for risk of exacerbations.
Respiratory Symptoms without Meeting COPD Diagnostic Criteria
The GOLD 2017 report and other reports have emphasized that many persons, particularly cigarette smokers, are likely to have a variety of respiratory symptoms without meeting the spirometric criterion for a diagnosis of COPD. Evaluation of over 400 current and former smokers with symptoms based on use of the COPD Assessment Test (CAT™ – see discussion in Appendix B) and a FEV1/FVC ratio >0.7 has demonstrated a significant increase in exacerbations of respiratory symptoms.10