Diagnostic Considerations for COPD in the Elderly
Symptoms of COPD in the elderly are nonspecific, and recognition and diagnosis are often delayed (Table 3). The vast majority of patients with COPD have a substantial history of smoking. Dyspnea and activity limitation are common symptoms, but these may be attributed to other potential underlying pathological abnormalities, including cardiac or other lung diseases. Many elderly patients limit their activity to avoid becoming dyspneic, and others assume that their dyspnea is resulting from their aging process and thus avoid seeking medical attention until later in their disease process. Wheezing can also be a presenting symptom. However, wheezing, like dyspnea, may be caused by non-COPD disorders such as asthma, bronchiectasis, or congestive heart failure (cardiac asthma). The presence of localized wheezing should trigger the possibility of a foreign object aspiration or malignancy. Cough is another very common symptom among elderly patients with COPD, but cough can also be caused by other respiratory or cardiac disorders as well as by medications such as angiotensin-converting enzyme (ACE) inhibitors. Physical findings in patients with mild disease may be absent. Thus the diagnosis of these patients should be based on a history of exposure to noxious agents such as cigarette smoke and the demonstration of airway obstruction on spirometric testing.
Objective measurements of lung function are needed to confirm the diagnosis of COPD in the elderly and to gauge its severity, which is often underestimated by the treating physicians. Both the American Thoracic/European Respiratory Society (ATS/ERS) and GOLD guideline have developed a simple classification of COPD based on the FEV1:FVC ratio and FEV1 (Table 4). To establish the presence of expiratory flow limitation, the postbronchodilator FEV1:FVC ratio is used. The GOLD guideline relies on a fixed ratio of <70% to confirm the presence of the obstruction. However, the use of a fixed FEV1:FVC ratio may overdiagnose obstruction in up to 35% of elderly, never-smoker, asymptomatic subjects.[25–27] Because lung elastic recoil diminishes with aging (see earlier discussion), the FEV1:FVC ratio in the elderly may drop below the proposed fixed ratio without the presence of a clinically significant disease state. Therefore, the ATS/ERS recommends defining the lowest 5% of the reference population as below the lower limit of normal (LLN) of FEV1:FVC ratio for diagnosis of obstruction. However, Mannino and colleagues, in a large cohort, reported a higher adjusted risk of death and COPD-related hospitalization in subjects with FEV1:FVC ratio <70% but above the LLN when compared with asymptomatic individuals with normal lung function. Spirometry may be difficult to perform in some situations in the elderly because of physical impairments and/or poor cognitive abilities. The FEV1:FEV6 (forced expiration for 6 seconds) ratio may be a good substitute for the FEV1:FVC ratio in elderly patients.
Measurement of lung volumes and diffusing capacity may, on occasion, help exclude restrictive diseases or asthma. Although findings on the chest radiograph are often nonspecific, it is recommended that one be obtained in the initial workup of an elderly patient presenting with possible COPD to rule out other coexisting conditions such as lung cancer. In addition, assessment of oxygenation status using rest/exercise pulse oximetry and/or arterial blood gases may identify patients who are hypoxemic. Whereas the normal PaO2 declines with age [PaO2 = 109 -0.43 (age in years)], PaCO2 should remain constant and within the normal range for younger individuals. Consequently, the normal alveolar-arterial oxygen difference increases with aging. The normal value for this A-a difference corrected to age can be calculated using the following equation [P(A-a) O2 = 2.5 + 0.21 × (age in years)]. Measuring the distance covered during a 6-minute walk test (6MWT) and oxyhemoglobin saturation during the walk via pulse oximetry may be helpful in assessing the exercise tolerance of patients with COPD, detecting exertional hypoxemia, and assessing response to therapeutic interventions.
Although FEV1 does not fully explain the complex clinical pathophysiological consequences of COPD, it is a simple and reproducible spirometric measurement that provides a reasonable marker in predicting morbidity and mortality in COPD. Celli and colleagues developed a relatively simple approach to identifying disease severity by using a multidimensional grading system to assess respiratory and systemic expressions of COPD. The composite score for body mass index, obstruction, dyspnea, and exercise tolerance (the BODE index), was found to be better than the FEV1 at predicting risk of death from any cause and from respiratory causes in patients with COPD. Such multidimensional indices have not been validated in elderly patients with COPD.
COPD is frequently complicated by the presence of several systemic comorbidities. These comorbidities are especially common in the elderly population and may be related to the duration of smoke exposure or to the systemic inflammation that is present in patients with COPD. Cardiovascular, musculoskeletal (cachexia, muscle dysfunction, and osteoporosis), and psychological (anxiety and depression) comorbidities are very common and can complicate the course of the disease. Therefore it is imperative that clinicians evaluate the elderly patient with COPD for the presence of such comorbidities.
Acute Exacerbations of COPD
Acute exacerbations of COPD (AECOPD) are very common in patients with severe and very severe COPD and are characterized by increased dyspnea, sputum volume, and purulence, beyond day-to-day variations to the extent that changes in therapy are warranted. Acute exacerbations present a risk for acute respiratory failure, and it is estimated that elderly patients with advanced COPD experience an average of two to three exacerbations each year, with each lasting 12 days. Bacterial and viral infections are the most frequent causes of exacerbations, but other triggers include air pollution and environmental temperature changes. Acute exacerbations of COPD are associated with worse quality of life, accelerated lung function decline, increased utilization of health care resources, and increased mortality.
The clinical presentation and outcome of COPD exacerbations may differ significantly in elderly compared with middle-aged COPD patients, which is likely explained by host and environmental factors. These host-related factors are likely linked to age-associated changes in respiratory structure and functional decline, and consequently the respiratory reserve to deal with acute illnesses becomes more limited. Elderly patients may not able to handle the increased secretions during an AECOPD episode as well as younger patients. Additionally, changes in other organs and the presence of comorbid conditions make it more difficult for them to deal with the stress of an acute illness. Lastly, the ability to metabolize and eliminate pharmacotherapeutic agents may decline with advancing age, which potentially increases the risk of adverse events with medications given as maintenance therapies or for AECOPD episodes. Because elderly patients are more likely to use multiple drugs for a variety of conditions, such polypharmacy may complicate disease management and increase the likelihood of adverse events due to drug interactions.
The risk of developing various comorbid medical conditions such as congestive heart failure (CHF) and pulmonary emboli increases with aging, and such comorbid conditions may mimic or complicate the presentation of acute COPD exacerbations. For example, it is not rare that a patient admitted to the hospital with an AECOPD episode develops acute myocardial infarction or serious cardiac rhythm disturbances as a consequence of hypoxia or as an adverse effect of bronchodilator therapy. Furthermore, institutionalized elderly patients may be colonized with more drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus, and Pseudomonas aeruginosa and other gram-negative organisms compared with noninstitutionalized elderly patients, and the presence of such organisms in respiratory secretions may influence the choice of antibiotic therapy they receive.[34,5]
Semin Respir Crit Care Med. 2010;31(5):596-606. © 2010 Thieme Medical Publishers
Cite this: COPD in the Elderly Patient - Medscape - Oct 01, 2010.