How frequently is asthma overlooked or misdiagnosed in older adults?
Chronic obstructive pulmonary disease (COPD) is recognized as a common condition in older adults, but asthma is often considered something that most patients outgrow long before they retire and qualify for Medicare. In contrast, the US National Health Interview Survey found that the lifetime prevalence of asthma in persons older than 65 years is 6.8%.1 This percentage translates into about 2 million persons in this age-group who have asthma. What if this figure is merely the tip of the iceberg?
UNDERESTIMATED PREVALENCE OF ASTHMA
A study of elderly patients in hospitals and nursing homes demonstrated that about 60% had an expiratory flow rate of less than 70%.2 Two-thirds of them had a 15% or greater improvement in expiratory flow after bronchodilator use, which suggests that the prevalence of asthma in the target population may be as high as 40%. However, only 6% of these patients were being treated for asthma.
Two limitations of this study are that it is “older” (1987) and includes a selected group of patients. A more recent trial noted that asthma was correctly diagnosed in only about 50% of elderly asthmatic patients. One-fifth of these patients were told that they had COPD, and about a quarter that they had no lung problems!3 This month’s Top Paper puts out a clarion call for reevaluation of the complications and morbidity of asthma in the elderly population.4 It ascribes our problems of oversight to a number of unique features in elderly asthmatic patients, who present later and with more severe lung disease than their younger counterparts. Older patients have reduced awareness of respiratory problems, especially air hunger and bronchoconstriction.
They respond less drastically to hypoxia and hypercarbia and therefore complain later of pulmonary symptoms. Although older patients are less likely to have overt symptoms, they are more likely to die of asthma than younger patients. In fact, half of all asthma-related deaths occur in persons older than 65 years. Despite the magnitude of the problem, the natural history of the disease in this population and the contributions from asthma triggers (allergic and otherwise)—as well as the appropriate management—remain unclear. What is clear is that asthma must be seriously considered in elderly patients.
What are the lessons from this study? First, measuring expiratory flow rate or performing handheld spirometry in elderly patients is worthwhile. Second, COPD is not the cause of all airflow-obstruction disorders in this group. Third, just as pediatricians remind other clinicians that children are not little adults, elders are not always like young adults. It seems this is especially true for the symptoms and treatment of asthma.
1. Moorman JE, Rudd RA, Johnson CA, et al; Centers for Disease Control and Prevention (CDC). National surveillance for asthma—United States 1980-2004. MMWR Surveill Summ. 2007;56:1-54.
2. Banerjee DK, Lee GS, Malik SK, Daly S. Underdiagnosis of asthma in the elderly. Br J Dis Chest. 1987;81:23-29.
3. Bellia V, Battaglia S, Catalano F, et al. Aging and disability affect misdiagnosis of COPD in elderly asthmatics: the SARA study. Chest. 2003;123:1066-1072.
4. Stupka E, deShazo R. Asthma in seniors, part 1: evidence for underdiagnosis, undertreatment, and increasing morbidity and mortality. Am J Med. 2009;122:6-11.