title: The FEF25-75/FVC ratio is associated with methacholine airway responsiveness. The normative aging study.
abstract: Airway responsiveness is known to be partly explained by geometric and anatomic factors. This cross-sectional investigation was undertaken to determine whether FEF25-75/FVC as a surrogate measure of airway size relative to lung size is associated with airway responsiveness to methacholine. Posteroanterior chest radiographs and spirometry were performed on a group of 929 middle aged and older men from an ongoing longitudinal study, the Normative Aging Study, who returned for their regularly scheduled examination between 1984 and 1989. Subjects had a mean age of 60.5 +/- 7.7 yr. FEV1, FEF25-75, and FVC were taken from spirometric results and FEF25-75/FVC ratios were obtained. Main bronchus (MB) and tracheal (TR) diameters and lung area (LA) were obtained from chest radiographs, and ratios of MB/LA and TR/LA were calculated for each subject and compared with FEF25-75/ FVC as measures of airway size relative to lung size. In a multiple linear regression model adjusting for age, height, initial FEV1, smoking, eosinophil count, and IgE level, FEF25-75/FVC was significantly related to the degree of methacholine airway responsiveness as measured by Log10 dose response slope (beta = -0.37, p < 0.001). Controlling for the same variables, both MB/LA (beta = -149.07, p < 0.001) and TR/LA (beta = -125.87, p < 0.001) were significant predictors of the degree of bronchial responsiveness in separate regression models; however, their effects were greatly attenuated when FEF25-75/ FVC was present in the same model. Similar results were obtained after excluding subjects with FEV1/ FVC </= 0.70 and subjects who had any smoking history. We conclude that FEF25-75/FVC as a surrogate measure of airway size relative to lung size is significantly associated with airway responsiveness.
authors.affiliation: Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, and VA Outpatient Clinic, Boston, Massachusetts, USA.
authors.forename: A A
authors.initials: AA
authors.lastname: Litonjua
authors.forename: D
authors.initials: D
authors.lastname: Sparrow
authors.forename: S T
authors.initials: ST
authors.lastname: Weiss
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D001980:Bronchi / Q000187:drug effects*; D016085:Bronchoconstrictor Agents / Q000494:pharmacology*; D001995:Bronchography; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging; D008297:Male; D008450:Maximal Midexpiratory Flow Rate / Q000502:physiology; D016210:Methacholine Chloride / Q000494:pharmacology*; D008875:Middle Aged; D013902:Radiography, Thoracic; D012016:Reference Values; D014132:Trachea / Q000000981:diagnostic imaging; D014797:Vital Capacity / Q000502:physiology
chemical_list: D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride