Chronic obstructive pulmonary diseases (COPD) and related diseases are the fourth leading cause of death in the United States, and death rates for these conditions rose 36 percent from 1979 through 1992 (Kochanek and Hudson, 1995). Pneumonia and influenza are the sixth leading cause of death, with an increase of 13 percent during the same period. As a cause of disability, lung disease ranked fifth when 5,201 older adults in the Cardiovascular Health Study (CHS) were asked about the cause of any disability in 17 specific tasks, accounting for 6 percent of task-disabilities (Ettinger et al., 1994). In the Framingham study cohort, persons diagnosed with COPD using spirometry were significantly more likely than unaffected persons to have disability in stair climbing, walking a mile, performing heavy home chores, and light housekeeping, but they did not differ in their ability to shop, carry bundles, or cook (Guccione et al., 1994); the results were adjusted for age, sex, and comorbidity. In another CHS analysis, self-reported lung disease was significantly associated with disability in each of four domains studied (which were similar to those used to screen the Women's Health and Aging Study [WHAS] population-see Chapter 1). However, lower forced expiratory volume in 1 second (FEV1), a measure of obstructive disease, was associated with difficulty only in the mobility and higher functioning domains, not with self-care or upper extremity disability (Fried et al., 1994).
Conversely, physical disability in walking a half-mile, climbing stairs, or performing heavy housework or activities of daily living (ADLs) is a possible risk factor for pneumonia-related mortality in older adults, after accounting for smoking and the effects of comorbidity (Salive et al., 1993). Taken together, the evidence presented above suggests that pulmonary conditions and physical disability can combine to trigger a spiraling decline in health among older adults that may result in death. This chapter examines the relation of pulmonary diseases and conditions, as well as physiologic measures of lung function, with age and disability in the WHAS.
About 10 percent of the women screened for the study reported a history of lung disease such as emphysema or chronic bronchitis (see Chapter 1, Table 1.3). In the total screened population, self-reported lung disease was related to disability: 17 percent of those who were eligible for the study reported such disease compared with only 7 percent among ineligible women who were not disabled.
Although 16 percent of study participants reported a lifetime history of chronic bronchitis, only half that number reported that they currently have the condition ( Table 11.1 ). Nine percent of participants reported a physician diagnosis of emphysema. While 11 percent reported a lifetime history of asthma, only 8 percent reported currently having asthma. Thirteen percent reported a history of pneumonia within 5 years of the baseline interview; slightly over half of these cases required hospitalization.
In the total population, self-reported pulmonary diseases appear to decline in prevalence with age. This decline parallels reported smoking in the study group. Thirteen percent of the women enrolled in the study were current smokers, ranging from 18 percent among the 65 to 74 year age group to only 6 percent in the women age 85 years and older (see Chapter 5, Table 5.3). Table 11.1 shows the prevalence of pulmonary conditions according to smoking status. For each age group and all disability levels, current and former smokers had substantially higher rates of chronic bronchitis and emphysema than never smokers. Overall, 14 percent of current smokers reported emphysema compared with only 3 percent of never smokers. Figure 11.1 shows the prevalence of chronic bronchitis and emphysema for never, former, and current smokers. There is a clear increase in the prevalence of chronic bronchitis across these smoking categories, with 19 percent of current smokers reporting current bronchitis. Emphysema was equally common in former and current smokers (14 percent). Asthma rates were unrelated to smoking status. Even after stratification by smoking status, chronic bronchitis and emphysema generally decrease in prevalence with age, probably as a result of high mortality rates in older people who have these conditions. Contrary to expectations, prevalence of chronic lung diseases did not increase according to disability level, possibly because of competing risks from other tobacco-related illnesses and selective survival of the never smokers.
A series of 18 questions derived from the American Thoracic Society questionnaire (Ferris, 1978) was asked to determine symptoms of pulmonary disease (Table 11.2). Twenty percent of participants reported usually coughing in the morning, and 22 percent reported coughing during the rest of the day or at night. Overall, 30 percent of participants reported a history of a regular cough either upon arising or during the day or night, or both. The majority of these women have had their cough for more than a year. Production of phlegm was also a common complaint, reported by 31 percent of women in the study, more commonly upon getting up in the morning. Again, most participants who produced phlegm reported that they had done so for more than a year. Cough and phlegm production were lower in the oldest age group, parallel to reported smoking.
While about two in five participants reported a wheezing sound from their chests during a common cold episode, only 16 percent reported wheezing apart from a cold, and less than half of these persons (8 percent) had it most days or nights. Among those who had a wheezing sound without a cold, most reported a duration of more than a year. Wheezing symptoms apart from a cold and wheezing most days or nights were inversely associated with age and modestly higher in the group with more severe disability. One in five persons reported wheezing attacks resulting in shortness of breath, of whom 15 percent required treatment. In contrast to the reported prevalence of respiratory disease, respiratory symptom prevalence was often greater among those who reported disability.
Lung function was measured in the home examination according to a standard protocol based on the guidelines of the Epidemiology Standardization Project (Ferris, 1978) and the American Thoracic Society (1991). A PJ5 Spirometer with a pneumotachograph (Tamarac Co.) was connected to an IBM-compatible notebook computer (Zeos International, Ltd., Minneapolis, MN) using software developed and modified by the National Institute for Occupational Safety and Health (NIOSH). The nurses performing the examination were trained and certified, and their performance was closely monitored by NIOSH staff.
During at least five forced expirations, the nurse attempted to obtain three acceptable spirograms with at least two having similar results (within 5 percent) for FEV1 and forced vital capacity (FVC). The acceptability and reproducibility of the spirograms were indicated by the computer program, confirmed by the nurse, and ultimately determined at the NIOSH reading center. The largest FEV1 and the largest FVC on any of the acceptable tests were reported (American Thoracic Society, 1991). Sex-specific predicted values for FEV1 and FVC, adjusted for age and height, were computed from Knudson's equations (Knudson et al., 1983).
Exclusionary criteria for spirometry were the report of any of the following within the 6 weeks prior to the examination: chest or abdominal surgery (n=8), hospitalization for a heart attack (n=4) or other heart problem (n=23), or detached retina or eye surgery (n=20). Three persons who had been hospitalized for a respiratory infection within 3 weeks prior to the examination and 84 additional persons were excluded at the discretion of the examiner, for an overall total of 142 persons excluded from the testing for medical or safety reasons.
Among those not excluded, nine participants refused to complete the spirometry examination, two were physically unable to cooperate, and two were unable to follow the instructions of the examiner. Seven persons were unable to complete the examination owing to equipment failure. Overall, 840 persons completed spirometry for a completion rate of 85 percent (Table 11.3). The completion rate was higher in the youngest age group and slightly lower among persons with more severe disability. Among those who completed testing, 77 percent had reproducible tests. The reproducibility rate was unrelated to age but was somewhat lower among women with more severe disability.
Spirometry examination results are presented in Table 11.4 only for persons with reproducible tests. The mean FEV1 was 1.4 liters, slightly lower among the oldest women and those with the most severe disability. The forced expiratory volume in 6 seconds (FEV6) approximates the total expiratory volume without depending on the duration of the test, as does the FVC. The mean FEV6 was 1.9 liters and also was lower with increasing age and disability. The FVC showed slightly higher results, particularly among the women with the best pulmonary function (95th percentile). The mean ratios of FEV1/FEV6 and FEV1/FVC showed little variation by age or disability level, although in the lower end of the distribution (5th and 25th percentiles) there is evidence of possible obstructive changes. The mean predicted volumes also have little variation by age or disability level but a considerable range in their distributions.
Tables 11.5 and 11.6 present the data on physiologic impairment based on two methods of spirometry interpretation. Table 11.5 presents NIOSH interpretations, with normal values at or above the 5th percentile based on the predicted values of Knudson and colleagues (1983). This interpretation suggests that only a slight majority (52 percent) have normal pulmonary function as assessed by spirometry. Table 11.6 presents the results using a different method, based on the recommendations of the American Thoracic Society (1991). Distributions of the spirometry variables from a benchmark subgroup of the study population-composed of never smokers who did not report cough, sputum production, or wheezing (n=205)-were used to develop normal values, considered to be at or above the fifth percentile. Using these criteria, only one-quarter of the population was found to have any abnormality (Table 11.6). Eighteen percent of participants had an obstructive pattern, with prevalence decreasing with increasing age and level of disability. Conversely, a restrictive pattern was highest among women age 85 years and older and women who received help with ADLs. Similar relationships of obstructive and restrictive lung disease with age and disability level were seen using the NIOSH interpretations (Table 11.5).
Much of the relation of self-reported lung diseases and symptoms to age and disability can be explained by age and smoking status. Spirometry examination was successfully completed in the home by about two-thirds of study participants. Successful pulmonary function testing was inversely related to disability but not to age. The results from this examination may be useful to further explore the relation of lung function to physical disability in this cohort of moderately to severely disabled older women.
The NIOSH laboratory is under the overall guidance of John Hankinson, Ph.D. Special thanks to Jeff Rushford and Betsy Viola of NIOSH for their contributions to spirometry training and data management.
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