Abstract
To determine the correlates of the lability of peak expiratory flow (PEF) in the elderly. A community sample of 4,581 persons > or = 65 years old from the Cardiovascular Health Study completed an asthma questionnaire and underwent spirometry. During a follow-up examination of the cohort, 1,836 persons agreed to measure PEF at home twice daily for 2 weeks, and 90% successfully obtained at least 4 days of valid measurements. PEF lability was calculated as the highest daily (PEF maximum - PEF minimum)/mean PEF. Mean PEF measured at home was accurate when compared to PEF determined by spirometry in the clinic. Mean PEF lability was 18% in those with current asthma (n = 165) vs 12% in healthy nonsmokers (upper limit of normal, 29%). Approximately 26% of those with asthma and 14% of the other participants had abnormally high PEF lability (> 29%). After excluding participants with asthma, other independent predictors of high PEF lability included black race, current and former smoking, airway obstruction on spirometry, daytime sleepiness, recent wheezing, chronic cough, emphysema, and wheezing from lying in a supine position. Despite having a lower mean PEF, those reporting congestive heart failure (n = 82) did not have significantly higher PEF lability. Measurement of PEF lability at home is highly successful in elderly persons. PEF lability > or = 30% is abnormal in the elderly and is associated with asthma.
Highlights
Those with valid peak expiratory flow (PEF) lability results were significantly more likely to be male, white, with a higher family income, Ͻ 75 years old, and less likely to have a history of asthma, and less likely to have chronic bronchitis, hay fever, emphysema, and congestive heart failure (Table 1)
Increased PEF lability is common in patients with asthma and is moderately associated with nonspecific bronchial hyperresponsiveness, as measured by methacholine or histamine challenge[20,21,22]; the correlates of PEF lability should be similar to those of bronchial hyperresponsiveness
In other population samples of younger adults, even after excluding those with asthma or COPD due to cigarette smoking, increased PEF lability was associated with respiratory symptoms like wheezing, nocturnal dyspnea, exertional dyspnea, seasonal rhinitis, and chronic cough.[2,3,5,20,24]
Summary
To determine the correlates of the lability of peak expiratory flow (PEF) in the elderly. Results: Mean PEF measured at home was accurate when compared to PEF determined by spirometry in the clinic. Mean PEF lability was 18% in those with current asthma (n ؍165) vs 12% in healthy nonsmokers (upper limit of normal, 29%). 26% of those with asthma and 14% of the other participants had abnormally high PEF lability (> 29%). After excluding participants with asthma, other independent predictors of high PEF lability included black race, current and former smoking, airway obstruction on spirometry, daytime sleepiness, recent wheezing, chronic cough, emphysema, and wheezing from lying in a supine position. Conclusions: Measurement of PEF lability at home is highly successful in elderly persons. PEF lability > 30% is abnormal in the elderly and is associated with asthma. The 1993–1994 CHS examination provided comprehensive measures of cardiovascular disease and risk factors from a representative sample of elderly persons from four US communities, as well as spirom-
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