ASTHMA IS MISDIAGNOSED AND UNDERTREATED IN THE ELDERLY

TUCSON-Asthma diagnosis in patients older than age 65 years is only half as good as it should be; 50% of elderly asthmatics have not been diagnosed, and only 30% of diagnosed patients are treated with inhaled corticosteroids. That finding may help explain why the asthma death rate in adults older than age 65 years is 10 times the death rate in younger adults, said researcher Paul L. Enright, MD, and colleagues.¹

As part of the Cardiovascular Health Study (CHS) Research Group, Dr. Enright, who is research associate professor at the University of Arizona, in Tucson, and colleagues used data from the CHS to explore the effects of asthma in community-living elderly upon quality of life (QOL), morbidity, and use of asthma medications. The CHS researchers had been concerned about the impact of asthma on cardiovascular health and had included appropriate measures in the study design. Prior studies of QOL in asthma included only younger subjects.

"I was asked to be the 'pulmonary expert' for the multicenter CHS even before it began, over 10 years ago," Dr. Enright explained. "Asthma and smoking-related lung diseases are common in elderly persons, so we prospectively decided to ask questions about these lung diseases and perform spirometry for all study participants. After examining the prevalence of asthma during the CHS baseline exam, we decided to ask more extensive, standardized questions about asthma during the sixth follow-up exam and to obtain an index of bronchial lability."

Therefore, CHS examinations (conducted between May 1993 and June 1994) included not only comprehensive measures of cardiovascular disease and risk factors, but also spirometry and standardized questions about asthma symptoms and triggers. Patients were also asked to participate in an optional study of peak flow lability, using home peak expiratory flow (PEF) meters.

"We decided to ask the participants to measure [PEF] at home for several days instead of performing a methacholine challenge test or the response to inhaled bronchodilator, which requires more clinic staff time," Dr. Enright said. "When told it was optional, only 40% of the study participants agreed to measure their [PEF] at home for one week." Elderly patients with asthma, he suggested, will be more likely than CHS participants to try to use lung function testing at home to help manage their asthma. Peak flow monitoring may be most useful for elderly persons with asthma who have demonstrated high airway lability, are well-educated, are poor perceivers of bronchoconstriction, and who want to participate in their asthma management in order to minimize the need for prednisone.

The researchers found that 4% of all of the CHS participants reported definite asthma, an additional 4% reported probable asthma, and 11% reported possible asthma (see Sidebar). To avoid the possibility that reported symptoms might be due to smoking or to congestive heart failure (CHF) rather than to asthma alone, smokers and those with CHF were excluded from the final analysis, leaving 2,527 participants (out of a community sample of 4,581 persons).

"Since the CHS participants were a random sample of the Medicare eligible population from four US communities, I believe our results are highly generalizable to ambulatory elderly patients seen by primary care providers in the United States," Dr. Enright said.

The researchers slightly modified the Global Initiative for Asthma (GIA) criterion for severe asthma, which is forced expiratory volume in 1 second (FEV₁) of less than 60% of predicted. Since that criterion produced "unreasonably high" proportions of "severe" asthmatics among the elderly patients, Dr. Enright and colleagues used FEV₁ of less than 50% of predicted as the cutoff for severe asthma, 50% to 69% for moderate asthma, and 70% to 79% for mild asthma. The data showed many more cases of probable or possible asthma than had been diagnosed; another crucial finding was that a relatively high proportion of those patients had severe disease (Table 1).

"About 10% of those with possible asthma and 16% of those with probable asthma were categorized as having 'severe persistent asthma' although they did not have a diagnosis of asthma," Dr. Enright reported.

Asthma symptoms were triggered or made worse by dust, smoke, or fumes; colds, sore throats, or flu; exercise or exertion; contact with animals, plants, or pollens; or lying down flat or sleeping. Two thirds of patients with probable or definite asthma reported dyspnea while walking quickly, and 16% reported shortness of breath while walking on level ground at their own pace.

The implications for QOL are obvious and were supported by the QOL data. Patients with any level of asthma--even very moderate--were more likely to rate their general health as fair or poor and to report that their level of activity was less than in the previous year. About half said that "everything was an effort" in the previous two weeks. Asthma and poor QOL in turn affected overall well-being. These patients were twice as likely to have symptoms of depression.

Patients with possible, probable, or definite asthma were more likely than others to wake up in the middle of the night with coughing, with chest tightness or pain, or with trouble breathing. Not surprisingly, they were also twice as likely to report daytime sleepiness.

"The large number of elderly persons who have asthma symptoms identified by this study--but who have not received a diagnosis of asthma--is disturbing because they are experiencing reduced QOL and considerable morbidity associated with their asthma, which may be largely preventable," Dr. Enright noted. "If the diagnosis were made, 23% of those with possible asthma and 27% of those with probable asthma would be categorized as having moderate or severe persistent asthma, for which daily inhaled corticosteroid medications are indicated."

Unfortunately, elderly asthmatics who manage to get diagnosed are not usually receiving what is now standard therapy (Table 2). Clinical guidelines recommend daily anti-inflammatory medications, such as inhaled corticosteroids, plus rescue use of long-acting bronchodilators for patients with moderate or severe persistent asthma. Inhaled corticosteroids rarely cause side effects and minimize the need for chronic oral corticosteroids, such as prednisone, which are associated with a high risk of side effects in the elderly.

The CHS data showed that only 30% of those with definite asthma were taking inhaled corticosteroids, while 40% were taking inhaled or oral sympathomimetics and 18.5% were taking oral corticosteroids. Thirty-nine percent were not using any asthma medication, including 6 of the 20 patients with severe asthma. "It is worrisome that a relatively high proportion (18%) of our elderly participants with definite asthma (regardless of their smoking history) were taking oral corticosteroids," Dr. Enright commented.

Of further concern was the finding that while only 39% of patients with definite asthma were on inhaled corticosteroids, 44% had received allergy shots. "I was personally surprised that most elderly persons identified allergic factors exacerbating their asthma, and that many had tried allergy shots (which are relatively ineffective), yet few are routinely using inhaled corticosteroids, which are highly effective and low risk," Dr. Enright said. "Pulmonary physicians must act to reduce the steroid phobia preventing many primary care providers and their patients with asthma from 'putting out the fire' in their airways."

The key to improving the treatment of asthma in the elderly is clearly to improve the rate of diagnosis. The CHS researchers recommend the wider use of office spirometers to confirm the presence of airway obstruction in patients with symptoms suggesting possible or probable asthma, as well as a baseline FEV₁ for monitoring lung function in response to therapy. In the absence of office spirometry, they suggested home peak flow lability measurements using a $20 mechanical peak flow meter.

The researchers even advised that smokers who have asthma-like symptoms and airway obstruction should be treated with a 2-week clinical trial of corticosteroids and bronchodilators. In fact, about 10% of current or former smokers who are believed to have chronic obstructive pulmonary disease (COPD) are actually "hidden asthmatics" and will respond with a substantial increase in lung function.

"The findings of this study should cause primary care providers to obtain spirometry testing to help confirm their suspicions of asthma or COPD for elderly persons with respiratory symptoms, regardless of their smoking status," Dr. Enright advised. "Treatment for asthma in the elderly should be more aggressive and should follow current clinical practice guidelines--which emphasize the routine use of inhaled corticosteroids--in order to improve the quality of life of active senior citizens.

"I suspect that the vast underdiagnosis of asthma in the elderly is due to common misperceptions that asthma is primarily a disease of childhood, rarely starts for the first time in [the elderly], and that episodes of shortness of breath in the elderly are inevitable, or usually due to heart disease."

-Janis Kelly

Reference
1. Enright PL, McClelland RL, Newman AB, et al. Underdiagnosis and undertreatment of asthma in the elderly. Chest. 1999;116:603-613.