Determinants of Percent Predicted FEVi in Current Asthmatic Subjects: Comment
We also did not find that age of onset of asthma or duration of disease were related to %FEVi. These results contrast with those of Braman and coworkers, who reported that among 25 asthmatic patients more than 70 years old, those with late-onset asthma had better lung function than those who had reported a mean duration of illness of more than 30 years. Both differences in study populations and methodology probably explain these disparate results. Among our subjects, concomitant diagnoses, which we have shown to adversely affect pulmonary function, tend to accumulate with age so that nearly half of our subjects over age 60 years, for example, have a diagnosis of both asthma and chronic bronchitis. This combination of diagnoses, as we have shown, is associated with a decreased %FEVi, and as a result, our older asthmatic subjects have generally lower pulmonary function no matter when their asthma was diagnosed. Such patients were excluded from the study of Braman et al.
Also, because we studied a large number of subjects with a broad age range, we were able to use multiple regression to measure any relationship between duration of illness and %FEVi. In contrast, Braman and coworkers simply compared pulmonary function in their subjects who developed asthma before age 65 years with those who developed the disease after age 65. In analyses not shown here, we also grouped and compared our subjects as Braman et al did, and we did not find a significant difference in pulmonary function between the two groups. birth control online
While we expected that symptom severity and concomitant diagnoses would relate to %FEVi, we did not anticipate that %FEVi would decline with the combination of wheezing and age in our subjects. This decline occurred among subjects with mild symptoms as well as those with moderate or severe symptoms, as shown in Figure 2. Ulrik and colleagues also reported that lung function declines with age among asthmatic patients, both in crosssectional and in longitudinal analyses. The clinical importance of this decline among older subjects is unclear, since we have previously shown that low pulmonary function among asthmatic subjects does not portend the bad prognosis that it does in subjects with emphysema. We suspect, however, that the decline in pulmonary function which we observed reflects progression of asthma as well as other age-related physiologic changes.