Asthma and chronic obstructive pulmonary disease (COPD) are clinically important in older adults because like heart failure, they are common causes of chronic shortness of breath, which reduces the quality of life by limiting an individual’s activity. In developed countries, about 4% of older adults have been diagnosed with asthma and another 4% have been diagnosed with COPD, but the prevalence is doubled for each of these chronic respiratory diseases when objective tests are performed. COPD has become the fourth leading cause of death in some developed countries. COPD onset occurs almost exclusively in older age due to the cumulative effects of cigarette smoking in genetically-susceptible individuals. An upper respiratory viral infection commonly leads to the initial diagnosis of asthma at any age. About half of older adults with asthma have allergic triggers, compared to about 90% of asthmatic children. Exacerbations with dyspnea, wheezing and cough are the major morbidity of asthma and COPD, which limits activity, reduces quality of life and increases health care utilization and costs. In older adults as in younger adults, the most effective prevention for both asthma and COPD is smoking cessation.
KeywordsAging Epidemiology Geriatrics Older adults Longevity Asthma COPD Lung disease Spirometry Lung function Screening Risk factors Prevention Smoking
B-type natriuretic peptide
Chronic Heart Failure
Chronic Obstructive Pulmonary Disease
Carbon Monoxide Diffusing Capacity
Forced Expiratory Volume
Forced Vital Capacity
Lower Limit of the Normal range
Maximal Inspiratory Pressure
National Health and Nutrition Examination Survey
Prior to inhalation of a Bronchodilator
After inhalation of a Bronchodilator
Respiratory Syncytial Virus
The Epidemiology and Natural History of Asthma study
Asthma, chronic obstructive pulmonary disease (COPD) and chronic heart failure are clinically important in older adults because they are common causes of chronic shortness of breath (dyspnea), which reduces quality of life by limiting activity. An older adult with any of these diseases is more likely to experience morbidity (exacerbations and hospitalization) and mortality. Asthma and COPD both cause airway narrowing, which can be detected by spirometry testing. While asthma can start during any decade of life, COPD only develops after decades of cigarette smoking and so is very rare before 40 years of age. It is important to distinguish between asthma, COPD and heart failure because the interventions differ; treatment for asthma is more successful and the prognosis is much better. About 20% of older adults with any one of these causes of dyspnea will also have one of the others (co-morbid conditions).
The definitions of asthma and COPD are based on symptoms, self-reported diagnosis, and/or the testing of pulmonary function using spirometry. Asthma is defined as episodic and reversible airways obstruction. COPD is defined as chronic and irreversible airways obstruction. Other chronic conditions can also cause dyspnea. We define two of these here to distinguish them from asthma and COPD. The definition of chronic bronchitis is based on a history of a chronic cough (productive of sputum or not) which has been present for at least 2 years. Epidemiologic studies use a standardized set of questions to define chronic bronchitis; no objective tests are needed. Emphysema is a term used to describe the irreversible destruction of lung tissue, which is detected using a breathing test called carbon monoxide diffusing capacity (DLCO) or by high-resolution CT scans of the lungs that show reduced lung density or holes in the lungs (blebs or bullae). Overlap amongst the above chronic lung disease phenotypes does occur since decades of cigarette smoking can cause any one or all of them (asthma, chronic airway obstruction, chronic bronchitis and emphysema).
Airway obstruction is reliably detected in older adults through the use of a spirometer . The study participant is coached to take as deep a breath as possible and then blow into the spirometer mouthpiece as quickly as possible for at least 6 s. The volume of air forcefully exhaled during the first second is called the forced expiratory volume (FEV1) and the total amount of air exhaled is called the forced vital capacity (FVC) (measured in liters). Healthy middle-aged adults can exhale about 75% of their air in the first second, so the ratio of their FEV1/FVC is about 0.75. Smokers who have developed COPD have a permanently reduced capacity to exhale rapidly, so their FEV1 and their FEV1/FVC fall below the lower limit of the normal range (LLN).
24.4 Differentiating Asthma from COPD and Chronic Heart Failure (CHF)
Tests to differentiate asthma, chronic obstructive pulmonary disease, and chronic heart failure
Chronic obstructive pulmonary disease
Chronic heart failure
Low FVC (restriction)
Low ejection fraction
The agency which funds the majority of pulmonary research in the United States (US), the Lung Division of the National Heart, Lung and Blood Institute, made asthma a high priority in the 1980s–1990s, so standardization of asthma definitions was advanced for both reporting purposes and clinical practice guidelines. However, the emphasis was on the control of asthma in children. Although the US Centers for Disease Control and Prevention reported that the majority of asthma deaths occurred in older adults , very little asthma research (observational or intervention) was done in this age group. Around the year 2000, the Lung Division shifted its major research funding and disease awareness programs to COPD, a disease almost exclusively of older adults. Still, controversy exists regarding the definitions of asthma and COPD in older adults.
24.4.1 Controversy in Defining Asthma and COPD
Older adults who have respiratory symptoms and airway obstruction that remains post-BD are classified by some studies as having asthma and by others as having COPD. Asthma has to be defined on the basis of a physician diagnosis, but in the future, there should be some consideration of a reversibility of chronic obstruction. Some investigators use smoking status to classify the respiratory disease of those with post-BD airway obstruction (never smokers as having asthma or ever smokers as having COPD). Large epidemiological surveys of adults have demonstrated that about one-third of participants who have mild airway obstruction before inhaling a fast-acting bronchodilator (pre-BD) do not have airway obstruction post-BD. However, the majority of studies of chronic lung disease in adults do not take the time to perform post-BD spirometry (since it takes 15–20 min).
A chronic cough is a very common feature in smokers who have developed COPD, so some studies wrongly include people with a chronic cough or chronic bronchitis under their definition of COPD. However, even in adult smokers, there are many other causes for a chronic cough (e.g., rhinosinusitis, gastro-esophageal reflux and asthma), so large COPD misclassification rates result when an objective measurement of airway obstruction is not performed.
The definition of asthma for epidemiological surveys is less controversial than for COPD [7, 8]. For diagnosis of asthma, most studies of adults rely on participant recollection of a physician diagnosis of asthma, using a set of standardized questions. Study participants may also be asked to list their breathing medications or to bring them to a study visit. Objective measurements of the bronchial hyper-responsiveness (BHR) and eosinophilic airway inflammation of asthma are available , but they have not come into widespread use due to the time needed to perform the BHR measurement (45–60 min for a methacholine or mannitol inhalation challenge test) and the expense of exhaled nitric oxide analyzers. Also, as discussed above, a spirometry test only detects moderate or poorly-controlled asthma.
A physician diagnosis of asthma under-estimates the true prevalence of asthma because many people do not seek medical attention for what they consider to merely be “a cold that goes to my chest” . However, the morbidity that is experienced by older adults who have recurrent, intermittent episodes of wheezing with shortness of breath but no diagnosis of asthma is similar to those who have a diagnosis of asthma.
24.4.2 Implications of Disease Definitions
As with other common chronic diseases for which expensive drugs are available, the exact definition of the disease has large financial implications (for the payors and sometimes for the individual patients). The market for medications that control airway obstruction greatly expands when definitions for disease extend into the normal range and when clinical practice guidelines call for early detection and treatment of more mild disease. Currently, there is no evidence that early detection and treatment changes the natural history of COPD.
24.5 Prevalence and Incidence
Population-based samples of older adults have provided estimates of the prevalence of asthma in adults ≥60 years of age [14, 15]. Using a large community-based cohort of individuals >65 years of age in the US, the CHS defined definite asthma as positive responses to the questions: “Has a physician ever told you that you have asthma?” and “Do you still have asthma?” Probable asthma was defined as a history of wheezing in the past year associated with chest tightness or breathlessness. Excluding smokers and those with a diagnosis of congestive heart failure, 4% of individuals had definite asthma and 4% had probable asthma . Among current smokers, 11% had definite asthma and 14% had probable asthma. The age of asthma onset was spread approximately evenly among decades, with 25% reporting onset before age 20 and 27% after age 60.
In the US, the National Health Interview Survey asks questions regarding lifetime history of asthma, current asthma prevalence, and asthma attacks in the last 12 months . For all age groups, asthma prevalence has been steadily increasing since 1980. For example, the prevalence of current asthma in those aged 65 and above rose from 6.0% in 2001 to 7.0% in 2004. For those ≥65 years of age, asthma is consistently more prevalent in women than in men. In 2003, 3.3% of women over age 65 reported an asthma attack during the previous 12 months, compared to 1.7% of older men. The National Center for Health Statistics tracks data on physician encounters for asthma. Using this data, the National Ambulatory Care Survey reported that those ≥65 years of age have the second-highest rate of outpatient office visits for asthma after preschool children, but do not have significantly different rates for emergency room visits compared to other adult age groups . The 65+ age group accounts for a greater proportion of hospitalizations (23%) than the size of its population (13%) would indicate, and has higher asthma mortality rates than do young adults .
24.6 Risk Factors
Within the age range of 65–95, the risk of the clinical appearance of asthma or COPD does not increase appreciably with age. Allergic asthma commonly begins in childhood, but it can begin at any age. Older patients who have asthma often note the onset of asthma after age 60, usually associated with a serious cold or influenza . In contrast, age is a risk factor for COPD since it develops very slowly, with the onset of dyspnea upon exertion prompting a diagnosis in the fifth or sixth decade of life. After age 85, the prevalence of COPD falls, probably due to mortality from other smoking-related diseases.
Aging is a cause of decreased lung function in older adults. Lung function grows with height in childhood and adolescence, reaches a peak in the 20s or early 30s then declines linearly throughout adulthood. FVC starts at 4–5 l in young adults (depending on height and gender) then declines by about one-third of a liter per decade. On average, the functional reserve of the lungs continues to slowly erode throughout older age, even in healthy individuals who have never smoked and had no measurable environmental exposures. The FEV1 declines at a somewhat faster rate than the FVC (largely due to a loss of lung tissue elasticity), so the FEV1/FVC also declines with aging. Age-related impairments in respiratory physiology become most problematic during maximal exercise or in an episode of acute lung injury (e.g., pneumonia), as well as in individuals who already have a reduced ventilatory reserve due to lung disease.
For a given exposure history (such as pack-years of smoking), women and men have a roughly equivalent risk of developing COPD [19, 20, 21]. Older women are more likely than older men to have asthma-like symptoms and to report dyspnea upon exertion (even after adjustment for other risk factors).
24.6.3 Genetic Risk
Studies have identified some racial differences in susceptibility to asthma and COPD. However, large projects have had only limited success in determining the exact set of genetic polymorphisms that are responsible for increased susceptibility for developing these chronic airway diseases . African-Americans are more likely to have a genetic polymorphism that increases their risk of asthma (at all ages) and reduces the effectiveness of the long-acting bronchodilators which are commonly used to control asthma (inhaled beta-agonists). Amongst Hispanics, a greater percentage of African ancestry correlates with lower FVC and a greater risk of asthma and asthma severity . On the other hand, African-American women are less susceptible to the risk that cigarette smoking will cause COPD .
About one in five people who begin smoking before age 20 will slowly develop COPD. About 90% of clinically-important COPD is caused by smoking. The respiratory system has a very large functional reserve, so decades of slow loss in lung function usually occurs (as in COPD caused by cigarette smoking) before shortness of breath prompts the individual to seek medical attention . Smoking also increases the risk of asthma (at all ages) and continued smoking makes asthma more difficult to control because smoking reduces the effectiveness of inhaled corticosteroid therapy.
All of the common respiratory viruses have been associated with asthma and COPD exacerbations: respiratory syncytial virus (RSV), parainfluenza viruses, coronaviruses, human metapneumovirus (hMPV) and rhinoviruses. Wheezing is a common symptom in older adults who are infected with any respiratory virus, particularly with RSV and hMPV, and 7 percent of adults who are hospitalized with RSV pneumonia will have a discharge diagnosis of asthma .
Many risk factors for asthma in young and middle-aged adults have been identified. Most remain as risk factors for asthma in older adults. In the CHS cohort, 58% of older-adult asthmatics reported the most common trigger of an asthma exacerbation to be an upper respiratory viral infection (upper respiratory infection, common cold or influenza), while 30% reported that contact with animals caused their asthma to worsen. Two-thirds reported seasonal worsening.
About 50% of older adults with asthma have allergic triggers, compared to about 90% of asthmatic children. The Epidemiology and Natural History of Asthma (TENOR) study compared the natural history of asthma in younger and older patients . The older patients had lower total immunoglobulin E (IgE) levels, fewer positive skin prick tests and less concomitant allergic rhinitis or atopic dermatitis. There is also evidence for an age-related decline in skin-prick test responses to allergens; however, older adults who have greater levels of IgE remain more likely to have allergic rhinitis and asthma .
24.6.7 Environmental Risk Factors
A few epidemiologic studies have suggested an association between short-term worsening of outdoor air pollution and emergency department or hospital admissions for asthma in older adults . Decades of exposure to severe outdoor air pollution may increase the risk of at least mild COPD in older ages . Like the skin, the lungs have a very large surface area which is directly exposed to the environment. Inflammatory responses to these exposures usually promote long-term health, but they can also cause long-term damage in a susceptible subset of individuals, damage which often accumulates decade-by-decade. Occupational exposures to inhaled dusts, fumes, smoke and chemicals increase the risk of chronic airway obstruction which persists into older age . Decades of exposure to second-hand smoke, or to smoke from cooking with biomass fuels in developing countries, increases the risk of chronic bronchitis . It remains unknown whether these environmental exposures also cause clinically-important COPD because almost all studies used pre-BD FEV1/FVC <0.70 to define COPD, which caused high false-positive rates for airway obstruction.
24.7 Dyspnea, the Primary Outcome of Asthma and COPD
Older adults with asthma or COPD frequently have respiratory symptoms such as chronic cough, phlegm and wheezing, all caused by their chronic airway inflammation . Reduced lung function causes shortness of breath which limits their activity, reduces the quality of their lives and prompts them to utilize health care during exacerbations (visit emergency departments, sometimes leading to hospitalizations) . This morbidity, along with the drugs prescribed for their dyspnea, is expensive [34, 35, 36].
Dyspnea is the most distressing feature of chronic lung disease and is a leading cause of disability and healthcare utilization . In the CHS cohort, dyspnea upon exertion was 1.6-fold more likely to be present in patients diagnosed with asthma than in those without the diagnosis . Asthma had a significant impact on quality of life, with 35% of older adults who have definite or probable asthma reporting a fair or poor health status compared to 17% of older adults who do not have asthma. Depression, restless sleep and daytime sleepiness were substantially more common in those with asthma.
Dyspnea may be considered an imbalance between ventilatory capacity and ventilatory demand. Increased ventilatory demand is commonly caused by comorbid conditions such as heart failure, anemia, obesity and peripheral vascular disease. The ability of the chest wall to expand easily is reduced by osteoporosis (vertebral compression, kyphosis and scoliosis) and osteoarthritis.
Very severe COPD and CHF (but not asthma) commonly cause skeletal muscle weakness (sarcopenia). Respiratory muscle weakness is a major factor that causes respiratory failure in COPD and pneumonia. The strength of the diaphragm, which is the primary breathing muscle, can be measured by a simple pressure meter. Maximal inspiratory pressure (MIP) ranges from 20 (very low) to 150 cm of water (normal), and is the best index of respiratory muscle strength . MIP is an independent predictor of all-cause, cardiovascular and respiratory death in older adults .
The most effective primary and secondary prevention for asthma and COPD after age 65 is the same as for middle age: smoking cessation. About half of older adults who have asthma and about one-third of those who have COPD are current smokers. Smoking cessation, both in middle age and older ages, is the only intervention that has been proven to slow the progression of COPD (thereby altering the natural history of the disease). Smoking cessation has been proven to make asthma respond better to inhaled corticosteroids, thus improving asthma control, and has been proven to prolong the life of those with COPD. The chronic cough and phlegm production of COPD will improve with successful smoking cessation, but the loss of lung function and emphysema are not reversible. The cough may get worse for a few weeks, but the degree of dyspnea on exertion tends to remain.
Influenza and pneumococcal vaccinations reduce asthma and COPD exacerbation rates . It is likely that avoiding exposure to young children who have upper respiratory infections also reduces the risk of exacerbations, but no clinical trials have studied the benefit of avoiding exposure to these young children.
Another prevention method for asthma and COPD is avoiding the inhalation of respiratory irritants (e.g., smoke, fumes, dusts chemicals), which cause airway inflammation that persists for several hours after inhalation. This temporary inflammation increases coughing and phlegm from the lower airways. It also causes nasal congestion, leading to mouth breathing which bypasses the heating, humidification and dust removal of nasal passages which naturally protects the lower airways (in the lungs).
Asthma, COPD and heart failure are clinically important in older adults because they are common causes of dyspnea, which reduces the quality of life by limiting activity. In developed countries, about 4% of older adults have been diagnosed with asthma and another 4% with COPD. Epidemiologic studies use standardized questionnaires to determine the presence of asthma and post-BD spirometry to detect and verify COPD. An upper respiratory viral infection commonly leads to the initial diagnosis of asthma in older adults. About 90% of COPD is due to the cumulative effects of cigarette smoking in genetically-susceptible individuals. About half of older adults with asthma have allergic triggers. Periodic exacerbations with dyspnea, wheezing and cough are the major morbidity of asthma and COPD. Both conditions are associated with a higher risk of death. In older adults, the most effective prevention for both asthma and COPD is smoking cessation.
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