Characteristics of Asthma among Elderly Adults in a Sample of the General Population

Characteristics of Asthma among Elderly Adults in a Sample of the General Population* Benjamin Burrows, M.D., F.C.C.E; Robert A. Barbee, M.D., F.C.C.E; Martha G. Cline, M.S.; Ronald] Knudson, M.D., F.C.C.R; and Michael D. Lebowitz, Ph.D., F.C.C.R

This article describes the characteristics and course of asthma among subjects who were older than 65 years at the time of enrollment in a longitudinal study of a general population sample. It was present in 3.8 percent of men and 7.1 percent of women. An additional 4.1 percent of men reported having "asthma," but they also had seen a physician for "emphysema" and had smoked signi6cantly; their "asthma·· diagnosis is regarded as highly questionable. They did not show the elevated rate of allergy skin test reactivity of high serum IgE levels that were characteristic of other asthmatics. Many of the elderly asthmatics (mean age, 72 years) had severe disease with marked ventilatory impairment. There was a close relationship between the severity of wheezing complaints and impairment of the FEV•• Of the 46 patients, 48 percent reported an onset before age 40 years. There was no relationship between severity and age of onset or duration of disease. A second diagnosis of"chronic bronchitis·· was reported by 46 percent of the asthmatics, but this did not delineate a distinctive

group with late-onset, smoking-related disease. Death rates in the asthmatics tended to be higher than in nonasthmatics (odds ratio, 1.9; CI, 0.998 to 3.70, after stratifying by sex). Over a mean follow-up of 7.44 years, most symptoms as well as the FEV. remained relatively stable. Chronic productive cough did tend to remit (p
asthma has been described as a Since disease ofadults. Indeed, as noted in an historical

women, the actual numbers of patients were nearly equal in the sexes. In both of these studies of elderly asthmatics, persistent airflow obstruction was present in most of the patients and corticosteroids were generally needed for effective therapy. We have been impressed by the number of elderly subjects, particularly women, who are being seen in our pulmonary disease clinic for what appears to be a persistent form of asthma. Despite this, there are few references dealing with the characteristics and course ofasthma in older adults. Indeed, the disorder is given scant attention in standard textbooks on geriatric medicine. To examine the nature of asthma in the elderl); we have analyzed findings in subjects reporting "asthma" among the 804 subjects who were aged 65 or older when they were enrolled in a longitudinal study of a general population sample in Tucson, AZ. Their mean age at the time of enrollment was approximately 73 years. The initial characteristics of the asthmatics in this population sample as well as their course during follow-up are reported.

antiqui~

review by Rosenblatt, 1 its clear recognition as a childhood disease appears to date only from the 18th centu~ with the contributions ofJohn Millar in 1760. In recent years, the pediatric onset of the illness is generally emphasized, and relatively little attention has been paid to asthma in elderly subjects, 2 even though the problem has been noted to be relatively frequent in general population studies. 3 •4 In 1973, Lee and Stretton5 drew attention to 15 subjects who appeared to have the onset of asthma after the age of 60 years and pointed out the difficulties of diagnosis in this age group. In 1979, Burr et al6 noted a high prevalence of active asthma (confirmed by clinical examination) in subjects older than 70 years in a community stud~ In this study from south Wales, the prevalence of the disease was much higher in men than in women (5.8 percent vs 1.8 percent), but because the overall sample consisted primarily of *From the Division of Respiratory Sciences, University of Arizona College of Medicine, Tucson. Sup~rted by a Specialized Center of Research Grant (HL 14136) from the Nationaf Heart, Lung, and Blood Institute Manuscript received February 7; accepted February 14 Reprint re~sts: Dr. Burrows, Respiratory Sciences, University of Arizona Health Sciences Center, Thcson 85724

= =

=

=

analysis ofvariance; CB chronic bronchitis; pkyrs pack-years; STpos positive to allergy skin tests; WZgrade wheezing grade

ANOVA

=

METHODS

The subjects are part ofa longitudinal study ofa stratified random cluster sample of white, non-Mexican-American households in CHEST I 100 I 4 I OCTOBER, 1991

93&

Tucson, AZ, in 1971 to 1972. Details of selection of the population sample have been published. 4 New members of these households have continued to be enraDed throughout the foDoWaup period. Some of the new enroUees were new spouses as weD as some parents who moved in with their children. Through the eighth survey of this population, completed in 1984, a total of 804 subjects aged 65 or more have been enroDed, 45 (6.0 percent) ofwhom were enroDed after survey 1. The mean age of the subjects at the time of enrollment was 72.8 ± 5.83 years (range, 65 to 95 years) and 57.6 percent were women. Details of the methods of testing have been provided in previous reports.4.7.8 Percent predicted values for spirometric variables were derived from reference equations for the population sample.' The percent predicted FEV1 is abbreviated as percent FEV1 •

A8thmtl on Enrollment Grad Prelimina,." Antilyses Some of the enraDed subjects have moved away from the Thcson area over the years. While most have continued to return foDoWaup self-eompletion questionnaires, including intitial forms for new household members, we have been able to obtain spirometric tests only by making periodic visits to parts ofthe United States in which there are clusters of out-migrants or by having such subjects come to our research clinic in Tucson when they are visiting the area. Also, some of these elderly subjects were unable to perform acceptable spirometeric tests. For these reasons, the data set is incomplete in regard to spirometric testing, serum IgE levels, and allergy skin tests. Of the total group of 804 subjects, 741 (92.2 percent) had satisfactory spirograms close to enrollment that are used to describe their initial characteristics, 749 (93.2 percent) had complete allergy skin tests, and 687 (85.5 percent) had serum IgE measurements. In order to age and sex standardize our serum IgE levels, they are expressed as 'cz scores" which represent the number ofstandard deviations by which an individuals log IgE value dHFers from the mean log IgE for their age-sex speci6c group. Age was stratified as 65 to 74 years and 75 + years as in a previous report. 10 Subjects are considered positive to allergy skin tests (STpos) if they have any reaction greater than control to a small battery of aeroallergens applied using the prick test technique. 7 Diagnoses are based on subjects' responses to direct questions concerning the presence of the diseases. Subjects are considered to have had elasthma" if they answered elyes" to UHave you ever had asthma?" The disease is considered active if the subject (1) claimed to "still have it;' (2) had more than rare "attacks of shortness of breath with wheezing," (3) had only rare attacks but admitted to wheezing "apart from coldS;' or (4) was talcing antiasthmatic therapy at the time of enrollment. Otherwise, the subject is considered to

have "exasthma:' "Emphysema" and "chronic bronchitis" are considered present if subjects answered that they still have the disease and had seen a physician for it. Using the de6nitions given above, there are 60 cases of apparent active "asthma" representing 7.5 percent of the study population aged 65 years and above. Of these, 27 are men (7.9 percent of all men) and 33 are women (7.1 percent ofall women). Possible diagnostic confusion between asthma and other forms of chronic airways disease was evaluated in these elderly subjects. In men, 17 (63.0 percent) of the patients with "asthma" reported emphysema as weD as asthma; in women, only four (12.1 percent) reported this combination. Some of these combined diagnoses occurred in subjects with little if any smoking history, but 14 of them were in subjects who had smoked at least 20 pacIc-years (pkyrs) ofcigarettes. One can not be certain that such subjects were truly asthmatic rather than having typical smoking-related chronic obstructive pulmonary disease (COPD) that showed some reversibility with bronchodilator therapy, leading to a secondary asthma label. 'Illble I compares subjects with a diagnosis of emphysema as well as asthma who had smoked at least 20 pkyrs (called "PAsthmaj with other asthmatics as well as with nonasthmatics and with the exasthmatics in the series. All of the 14 "PAsthma" patients are men. They have a signi6cantly lower mean percent FEV1 than any other group and do not show the immunologic characteristics of other asthmatics. Their serum IgE Z scores are not significantly di&'erent than nonasthmatics in the population and none of the 14 is STpos. In view of the uncertainty about their diagnoses, these subjects will not be included as asthma in subsequent analyses, leaving 13 men (3.8 percent ofall men) and 33 females (7.1 percent of all women) who were considered likely to be truly asthmatic at the time of entry to the stud~ The relationship between asthma and chronic bronchitis will be analyzed separatel~ There are 20 additional subjects in this age group who are classi6ed as exasthmatics by our criteria. They tend to be slightly more skin test positive than nonasthmatics but have no elevation of their serum IgE level; their mean IgE Z score is significantly lower than in active asthmatics (p<0.01). The mean percent FEV1 in these exasthmatics (95.9 percent) is slightly higher than in the overall group of nonasthmatics. To simplify presentation of the data, these exasthmatics as well as the upAsthma" group noted above have been excluded in the subsequent analyses that compare our 46 current asthmatics with the 724 subjects who denied ever having

asthma.

lbllow-up Studies FolloWaup data on the 804 subjects in the study were analyzed through the tenth survey of the population that was completed in

Table l-FEV., Allerlfl SIdn 1at ~ and Serum 19E in "P&llama".,. Other Groupa Exasthma

PAsthma

Asthma

(724) 42.0 72.9±5.90

(20) 50.0 73.1±5.14

(14) 100 73.3 ± 6.54

28.3 71.5±4.74

(663) 91.5±24.4

(18) 95.9±25.7

(14) 48.1±23.7

(46) 67.5 ± 23.9

(614) 1.25±.703 [17.9] -.064±.950

(18) 1.34± .812 [22.0] - .008± 1.106

(13) 1.45±.598 [28.0] .005±.776

(42) 1.84± .718 [68.6] .794±.988

(675) 21.0

(19) 36.8

(14) 0

(41) 36.6

No asthma

(Total n in group) Percent men Meanage±SD ,. Predicted FEV1 (N tested) Mean±SD, ,. Serum IgE, IU (N tested) Mean log IgE ± SD [Geometric mean] Mean Z score ± SD Allergy skin tests (N tested) ,. positive

(46)

*pAsthma == emphysema as well as asthma diagnosis and smoked 20 + pkyrs.

131

AsIhma among EIderty AduII8 (Bunowa et III)

30-. r------------------:;::::====;---,

«S

...

E

~

~

20-.

0

Q) ()

C

Q)

~

10-.

£L 0-. L---r-----r-{;;~;;l;~;;;.~:;;;;;-~m~ ;;;;:~.:f, < -1.6 (32)

-1.6<-.6 (166)

- .6<.6 (301)

.6<1.6 (164)

1.6 • (34)

Serum IgE Z Score FICURE 1. The relationship of current asthma prevalence to 19E Z score in the 687 subjects with serum IgE measurements. The 14 subjects with "PAsthma" noted in the text are not considered as asthmatics in these data, although their inclusion would not eliminate the overall trend and none falls in the lowest 19E category. The tendency for asthma prevalence to increase with 19E level is highly significant (p
January 1988. By that time, there bad been 454 deaths, an overall mortality of 56.5 percent. The mean questionnaire follow-up of the entire population was 7.44±5.0 years, and for surviwn it was 10.4 ± 4.9 years. FOr those who died, lOIlow-up questionnaires were available an average of 5.1 ± 3.7 yean after enroDment. There were no signillcant ditferences in the duration of lOIlow-up based on the asthma category at the time of entry. Among surviwrs, 89.6 percent bad follow-up spirometry compared with 76.1 percent of those who died. FoUo.up spirometry was obtained in 89.1 percent of all asthmatics and in 14 (93 percent) of 15 of asthmatic surviwn. The mean duration of spirometric lOIlow-up in all those foUowed was 7.2±4.7 years, 9.8±4.4 yean tor survivors, and 4.8±3.4 yean for those who died. More than four yean of spirometry IOIJow..up was available on 61 percent ofall asthmatics and 51 percent of all nonastIunatics. Thus, spirometric rollow-up tended to be more regular and slightly longer in asthmatics, but there were no statistically significant dJtFerences in the frequency or duration of spirometric lOIlow-up between them and the subjects who denied ever having asthma. Analyau

Analyses were carried out using SPSSIPC +. Stated probabilities are two tailed and were determined by analysis of YlIriance, regression analyses, Jt, trend Jt, or Mantel-Haenszel analysis of stratified data, as appropriate. Except for the FEV., tor which 1east squares regression slopes are reported, analyses compare the initial findings with those at the last follow-up on record. RESULTS

Asthma and IgE: As noted under the "Methods" section, the mean IgE of asthmatics is significantly elevated. Even in these elderly subjects, a minority of whom are STpos,

there is a very close relationship between the prevalence of asthma and age- and sex-standardized serum IgE level, as shown in Figure 1.

Smoking and Asthma The smoking histories ofour asthmatic subjects and the relationship of their smoking habits to some other characteristics are summarized and compared with findings in nonasthmatics in Thble 2. Even after excluding the 14 subjects who had smoked at least 20 pkyrs and who had both emphysema and asthma labels (see "Methods"), there are still a moderate number of smokers among our asthmatic subjects, and, in general, the smoking histories of these asthmatics differ relatively little from those of nonasthmatics. There tend to be fewer smokers of 20 + pkyrs and fewer current smokers in asthmatics of both sexes, but the differences are not statistically significant. In male asthmatics, there also tends to be a little less overall cigarette consumption, particularly among exsmokers, but these differences could be a result of exclusion criteria (see "Methods') and are not significant. The percent FEV. is much lower in nonasthmatic smokers than in other nonasthmatics, and in the nonasthmatics there is a highly significant correlation between percent FEV. and pkyrs (p
937

Table !-Stnoldng in ABIamtJtica .,. N~ No Asthma

Asthma Female

Male

(Total n at risk) (304) (420) Smoking history Smoking habits, % Current smoker 16.4 18.4 Exsmoker 14.3 49.3 Nonsmoker 69.3 32.2 Pack-years, mean ± SD Overall 29.4±31.5 8.8±18.5 In current smokers 5O.1±21.1 32.4±20.6 In exsmoken 4O.9±31.5 24.3±25.4 Smoked 20 or more pack-years 17.4 '11 of group 53.6 Relation of FEVI' serom IgE, and allergy skin tests to smoking Mean ~ predicted FEVI Smoked <20 pkyrs 95.7 ± 22.5 82.5 ± 25.9* Smoked 20 + pkyrs Mean IgE Z scores -.I34±.945 Smoked <20 pkyrs Smoked 20+ pkyrs .082±.945t '11 positive allergy skin test Smoked <20 pkyrs 23.0 17.0 Smoked 20 + pkyrs

Male

Female

(13)

(33)

15.2 46.2 38.5

9.1 15.2 75.8

19.3±25.4 55.7±8.0 23.2±24.9

8.5±22.3 39.8±14.7 34.4±41.2

38.5

12.1

67.0±21.8 69.5±32.8* .860±.984 .548±1.~

39.4 25.01

*p
smoking (Table 2). Among the asthmatics, there is no significant overall relation between smoking and IgE Z score. A slight but statistically significant elevation of the serum IgE level is noted in smokers of 20 + pkyrs among the nonasthmatics (p
significant correlation between percent FEV! and pkyrs. Asthma is associated with a significantly lower percent FEV! in both sexes after controlling for pkyrs of smoking (p
Table 3-Firatlinp in ~ tDIda and tDidwut "Clarotlic Bronclaitia" (CB)

(Total n)

Percent male Stated age of 8m attack, % Before age 16 yr Age 40 yr or more Repiratory trouble before age 16 yr, ., Smoking history, ., Current smoker Exsmoker Receiving therapy for asthma on enrollment, Chronic cough and/or sputum, If, Overall grade of wheezing (WZgrade), % 2 (Moderate) 3 (Severe) Grade 2 + exertional dyspnea, If, predicted FEVIt mean ± SD Allergy skin test positive, % IgE Z score, meao±SD

'*'*

'*'

Asthmatics

All

Asthmatics WithoutCB

Asthmatics WithCB

(46)

(25)

28

24

(21) 33

II 52 24 (8)·

8 52 12

14 52 38

II 24 67 67 (23)

8 20 64 52

14 29 71 86t

24 (4)

24 44 64 70.4±20.4

46 (7)

59 (18) 67.S±23.9 37 O.794±O.988

38

1.04± 1.00

24 48

52 63.9±27.6 35 0.485 ± 0.903

*Percentages in parentheses indicate prevalences in nooastbmatics. tp for difference between those with and without CB
138

A8hna among EIderty AduII8 (Burrows et 81)

smoking, the IgE Z scores in asthmatics are significantly higher than in nonasthmatics (p
These are summarized in the first column of Table 3. The severity of wheezing and the frequency of "attacks of shortness of breath with wheezing~~ are closely interrelated. To simplify presentation of the data, we have created a wheezing grade (WZgrade). Those with no more than rare attacks of shortness of breath with wheeze are given a WZgrade of 1 + (mild), those with more frequent attacks a grade of 2 + (moderate), and those with very frequent attacks or with wheezing on "most days" are given a WZgrade of3+ (severe). The stated age ofonset indicates that only 11 percent had their "first asthma attack" prior to age 16 years and 52 percent date it after 40 years of age. There are no significant differences between those claiming an onset after the age of 40 years and those with an earlier onset in regard to sex distribution, symptom severit}; rate of positive skin tests, mean IgE Z score, or percent FEV•. There is also no significant correla-

tion of IgE Z score or percent FEV} with the stated age ofonset or with the calculated duration of asthma. A somewhat larger fraction of asthmatics (24 percent) admit to "respiratory trouble before age 16" than date their first asthma attack to this age. As also seen in the first column ofTable 3, there are high prevalence rates of chronic cough and/or sputum and exertional dyspnea, as well as severe wheezing complaints, in asthmatics in this age group. (No significant differences in any of the findings were noted between the sexes, so they are combined in Table 3.) The prevalences of these symptoms in nonasthmatics are shown in parentheses; all are very much higher in asthmatics (p
100..

80'-

60t.

40..

...a....-

None (20)

--'-

Mild (14)

--'---

Moderate (11)

- - . . L_ _

Severe (21)

Grade of Wheezing Complaints FIGURE 2. The relationship of mean percent predicted FEV! to wheeze severity. By definition, exasthmatics have no signi6cant current wheezing and are given a grade of ccNone." The calculation of the grade of wheezing in current asthmatics (WZgrade) is explained in the text. Vertical bars indicate ± 1 SEM percent FEV! values for each of the groups and the number in each group is shown in parentheses. CHEST I 100 I 4 I OCTOBER, 1991

839

for severity of wheeze. Also, none of these is related significantly to WZgrade. A large fraction of these subjects (46 percent) reported "chronic bronchitis" (CB) as well as asthma. As seen in the last two columns of Table 3, there is significantly more frequent chronic cough and/or sputum in those with a CB diagnosis. There is only a slight relationship of a second label of CB to smoking history in asthmatics. Those with a CB label as well as asthma tend to report a somewhat earlier age of onset and a higher rate of "childhood respiratory trouble." The mean percent FEV. is somewhat lower in those with CB than in those without the second label. The IgE Z score tends to be lower in those with than in those without a CB diagnosis, but in both it is significantly higher than in nonasthmatics (p<0.02 for those with CB and <0.0001 for those without the second label). Except for cough and sputum prevalences, none of the differences between asthmatics with and without chronic bronchitis are statistically significant, largely owing to the small numbers in each group. There is an almost identical frequency of positive allergy skin tests in those with and without CB (35 percent vs 38 percent).

Course of the Disease The overall mortality by the tenth survey (16 years since the onset of the study) for asthmatics was 69.6 percent, not significantly different than the 64.1 percent for nonasthmatics. However, in men, 12 (92.3 percent) of the 13 asthmatics died while the death rate in male nonasthmatics was 67.1 percent. In women, 19 (57.6 percent) ofthe 33 asthmatics and 47.4 percent of the nonasthmatics had died by the end of followup. After stratifying by sex, the odds ratio for death in asthmatics vs nonasthmatics was 1.92 (confidence interval, 0.998 to 3.70), approaching statistical significance for an increase in mortality in these elderly asthmatics. The sex difference in survival among asthmatics (noted above) also approached significance (p = 0.06),

but there were no initial symptoms or other findings that related to survival, including the severity of wheezing complaints, the presence of chronic cough and/or sputum, reported CB, the smoking status at

the time of entry, a Significant overall smoking history (20+ pkyrs), allergy skin test status, percent FEV., or serum IgE levels. This contrasts with nonasthmatics in whom wheezing complaints, chronic cough and/or sputum, smoking status, and percent FEV. were all significantly related to mortali~ A comparison of symptoms at the beginning and end of follow-up for asthmatics with follow-up questionnaires is summarized in Table 4. Wheezing symptoms showed only slight and statistically insignificant tendencies to lessen in severity; there was some acquisition ofsuch symptoms in those not having them on entry and loss ofsymptoms in those with complaints on enrollment. The only complaint that diminished systematically was chronic cough and/or chronic sputum. Among those with follow-up, this was present in 67 percent of asthmatics at the time of entry but in only 33 percent on the last questionnaire (p
Although asthmatics had lower lung function than

nonasthmatics, the rates of decline in FEV1 tended to be lower in asthmatics than in those without asthma. When analyses were limited to the 28 asthmatics and

Table 4-Change. in Symptomafrom Entry to l..aIt Follow-up ita 43 A6thmtJttc SubJeca with Follow-up Que,tionntJitn %at Entry Wheeze apart from "colds" Frequent attacks short of breath with wheeze Severe WZgrade Chronic cough and/or chronic sputum Grade 2 + exertional dyspneat

85 40 45

67 62

% at Last Follow-up

% Developing Symptom

% Losing Symptom

71

7 17

22 24 24

33 36 33*

71

14 2 12

37 3

*The lower rate at follow-up was statistically signi6cant (p
372 nonasthmatics with at least four years of spirometric follow-up, the minimal duration previously considered adequate for reliable measurement of FEV1 slope,11 this difference (-8.0±24.2 vs -26.1±36.0 mllyear) was statistically significant (p<0.01). It remained significant after controlling for sex, current smoking, and initial percent FEV1 in an analysis of variance (ANOVA). None of these other factors proved independently predictive of FEV1 decline, and there were no significant interactions. There were too few asthmatics with adequate follow-up who were smoking at the time of enrollment to look at the effect of continuing smoking on decline in FEV1. DISCUSSION

Active asthma appears to be a relatively common problem in subjects older than 65 years who are part ofa population sample being followed up longitudinally in Tucson. Since our population could well be biased by selective in-migration to southern Arizona of patients with this type of disorder, we decided to send a brief questionnaire to 25 pulmonary physicians in other parts of the United States to determine whether they are seeing similar types of patients. It was completed by 23 of the 25 physicians contacted. One declined since he was no longer in active clinical practice and another declined because of his selected group of patients. All 23 of those completing the questionnaire did acknowledge that elderly patients with persistent asthma were not rare, but impressions ofthe syndrome differed to some degree. The majority of respondents reported that they could rarely if ever maintain the FEV1 at a normal level. Although the syndrome was considered more common in women than men, more often than the reverse, it was thought to be evenly distributed between the sexes by ten of the 23 respondents. Most believed that the syndrome had no relationship to smoking and only two related it to heavy smoking. The majority reported that a marked FEV1 response to steroids as well as steroid dependence was seen at least "often;" they also reported that the disease seldom dated back to childhood and usually began after the age of 40 years. As noted by others,5 the diagnosis of asthma among the elderly can be difficult. It may be unclear whether one is dealing with ordinary COPD, which shows some degree of response to therap~ rather than a persistent form of asthma, a disease which is easiest to diagnose with certainty in young subjects or when the lung function can be restored to near normal by vigorous therapy. The distinction is especially difficult in epidemiologic studies in which the database is limited and long-term responses to therapy cannot be evaluated. In an attempt to avoid including subjects with ordinary COPD, we decided a priori that those who reported that they had seen a physician for

"emphysema" as well as having asthma and who had a significant smoking history (arbitrarily considered 20 or more pkyrs) could not be classified as "asthma" with any confidence. There were only 14 such patients in our series, representing 1.7 percent of the total sample. However, they were all men (4.1 percent of all men), and in men the syndrome was slightly more common than "typical asthma." These subjects proved to have very severe airways obstruction and did not show the allergic characteristics (frequent STpos or high IgE levels) that typified the remaining 46 subjects who were considered likely to have a true asthmatic type of disease. Although less than 40 percent of the asthmatics had positive reactions to our small battery ofaeroallergen skin tests, the frequency of the disease was closely related to the age- and sex-standardized serum IgE level. This relationship was similar to that reported for asthmatics of all ages in this population sample,IO as seen in Figure 1. The 46 asthmatics were primarily women (72 percent). Only a small part of this preponderance of women is explained by the larger number of women in the total sample. While our overall asthma rate is similar to that reported in elderly subjects in Wales by Burr et al, 6 the sex distribution of our patients is very different. However, it is quite possible that even with similar diseases, more men than women were diagnosed as having CB and/or emphysema without an asthma label in our population and thus not identified as asthmatics in this stud~ The possibility of this type of diagnostic bias cannot be excluded. Only about half of these elderly asthmatics with an average age of72 years dated the onset of their disease after the age of 40 years, and 24 percent recalled having some type of respiratory problem before age 16 years. Although we consider these retrospective histories as relatively unreliable, it seems clear that a large proportion of these elderly asthmatics have had their disease for many years. Those claiming a late onset may well have had subclinical symptoms for many years prior to the time they recall as the onset of their disease. We were unable to demonstrate that the stated age ofonset or calculated duration ofdisease had a significant relationship to its severity or to its immunologic characteristics. As a group, these elderly asthmatics tended to have quite severe disease, and those with the most severe symptoms showed a marked reduction in their ventilatory function (Fig 2) which was always measured between acute exacerbations of their disease. The development of persistent airflow obstruction in severe asthmatics has also been noted by others. 12 The death rate for asthmatics tended to be slightly higher than that ofnonasthmatics, but otherwise, there was little evidence of systematic worsening of the disease over an average follow-up of more than seven CHEST I 100 I 4 I OCTOBER, 1991

941

years, either in terms of symptoms or lung function. Indeed, the decline in FEV 1was remarkably slow and significantly less than in nonasthmatics. The only symptom that appeared to change systematically was chronic cough and/or chronic sputum, which was less common at the end of follow-up than at the time of enrollment, a tendency that was also observed in our nonasthmatics. Overall, we estimate that no more than 19 percent of our asthmatics lost all evidence of active disease by the end of follow-up. Such apparent remissions were not seen at all in those with the most severe disease at the time of enrollment but were noted in almost half of the asthmatics with mild initial symptoms. It is impossible to determine from our data how the course of the disease was affected by therapy, especially since the sickest asthmatics were the most likely to be receiving therapy at the time of entry to the study. No significant effect of current or past smoking was observed, but it is likely that the most severe asthmatics tended not to smoke or to quit early if they began, a bias that would obscure any adverse effect of smoking on the disease. Except for a higher frequency of chronic productive cough, a tendency to more severe disease, and a slightly higher frequency of smoking, there was little difference between those who had been told they had CB as well as asthma and those with asthma alone. Those subjects with CB actually tended to recall childhood respiratory problems more frequently than those without this label and a minority had never smoked. Thus, contrary to our expectations, a label of CB plus asthma did not distinguish clearly those with an apparent late-onset, smoking-related disease. We question labeling subjects with asthma plus CB as "COPD," as has been done in some studies. 13 To do so may remove some of the most severe asthmatics from this diagnostic category. As we have reported previously, "chronic asthmatic bronchitis" appears to be a quite different disease than typical smoking-related "COPD."14 The major point of the article is to emphasize that asthma among the elderly is not a rare disorder, that it may be associated with severe and persistent ventilatory impairment, but, as noted previously in a

942

somewhat broader age group,14 it tends not to be a rapidly progressive form of airways obstructive disease. In subjects with severe disease, complete remission did not occur. Such subjects continued to have a severe and probably disabling degree of symptoms and ventilatory impairment throughout follow-up. REFERENCES 1 Rosenblatt MB. History of bronchial asthma. In: Weiss EB, Segal MS, eds. Bronchial asthma, 3rd 00. Boston: Little Brown & Co, 1976:5-17 2 Seaton A. Asthma in the eldery. In: Weiss EB, Segal MS, Stein M, OOs. Bronchial asthma, 2nd 00. Boston: Little Brown & Co, 1985:854-56 3 Broder I, Barlow P~ Horton RJM. The epidemiology of asthma and hay fever in a total community, Tecumseh, Michigan, I: description ofstudy and general6ndings. J Allergy 1962; 33:51323

4 Lebowitz MD, Knudson RJ, Burrows B. Tucson epidemiologic study ofobstructive lung disease, I: methodology and prevalence of disease. Am J Epidemiol1975; 102:137-52 5 Lee HY, Stretton TB. Asthma in the elderly. Br Med J 1973; 4:93-5 6 Burr ML, Charles TJ, Roy K, Seaton A. Asthma in the elderly: an epidemiologic survey. Br Med J 1979; 1:1041-44 7 Barbee RA, Lebowitz MD, Thompson HC, Burrows B. Immediate skin-test reactivity in a general population sample. Ann Intern Med 1976; 84:129-33 8 Barbee RA, Halonen M, Lebowitz MD, Burrows B. Distribution of IgE in a community population sample: correlations with age, sex and allergen skin test reactivity. J Allergy Clin Immunol 1981; 68:106-11 9 Knudson RJ, Lebowitz MD, Holberg CJ, Burrows B. Changes in the normal maximal expiratory Bow-volume curve with growth and aging. Am Rev Respir Dis 1983; 137:725-34 10 Burrows B, Martinez FD, Halonen M, Barbee RA, Cline MG. Association of asthma with serum IgE levels and skin-test reactivity to allergens. N Eng} J Med 1989; 320:271-77 11 Burrows B, Lebowitz MD, Camilli AE, Knudson RJ. Longitudinal changes in forced expiratory volume in one second in adults: methodologic considerations and 6ndings in healthy nonsmokers. Am Rev Respir Dis 1986; 133:974-80 12 Brown PJ, Greville HW: Finucane KE. Asthma and irreversible airflow obstruction. Thorax 1984; 39:131-36 13 McWhorter W~ Polis MA, Kaslow RA. Occurrence, predictors, and consequences of adult asthma in NHANESI and follow-up survey. Am Rev Respir Dis 1989; 139:721-24 14 Burrows B, Bloom ~ Traver GA, Cline MG. The course and prognosis of different forms of chronic airways obstruction in a sample from the general population. N Eng} J Moo 1987; 317:1309-14

Asthma among Elderly Adults (Burrows et 81)