Abstract • To determine the daily variability of spirometry, we performed spirometry on five consecutive days on 15 normal subjects and on 24 patients with chronic bronchitis. The patients with chronic bronchitis were divided into the following two groups: 13 with chronic airflow obstruction (forced expiratory volume in 1 s [FEV1] 80%, FEV,/forced vital capacity [FVC] ratio < 75%) and 11 without airflow obstruction (FEV1 and FVC > 80%). We attempted to control most of the factors known to affect spirometric variability. Our results indicate that the day-to-day FEV, has to change by 17% and the FVC by 15% in patients with airflow obstruction before the change should be considered significant. In patients with nonobstructive chronic bronchitis or in normal subjects, a greater than 5% change should occur in FEV, and FVC before considering the change to be significant. (Arch Intern Med 1982;142:1287-1291) References 1. Ciba Guest Symposium Report: Terminology, definition and classification of chronic pulmonary emphysema and related conditions. Thorax 1959;14:286-299.Crossref 2. American Thoracic Society: Snowbird workshop on standardization of spirometry. Am Rev Respir Dis 1979;119:831-838. 3. Smith AA, Gaensler EA: Timing of forced expiratory volume in one second. Am Rev Respir Dis 1975;112:882-884. 4. Kory RC, Callahan R, Boren HG, et al: The Veterans Administration-Army cooperative study of pulmonary function. Am J Med 1961;30:243.Crossref 5. Goldman AL: Influence of tracing selection techniques on daily variation of FEV, and FVC, abstracted. Am Rev Respir Dis 1979;119:218. 6. Sorensen JB, Morris AH, Crapo RO, et al: Selection of the best spirometric values for interpretation. Am Rev Respir Dis 1980;122:802-805. 7. McCarthy DS, Craig DB, Chernack RM: Effect of modification of the smoking habit on lung function. Am Rev Respir Dis 1976;114:103-113. 8. Snider GL, Rieger RA, Demas T, et al: Variations in the measurement of spirograms. Am J Med Sci 1967;254:679-684.Crossref 9. Hruby J, Butler J: Variability of routine pulmonary function tests. Thorax 1975;30:548-553.Crossref 10. Thiruvengadam KV, Kamat SR, Arunachalam K, et al: Diurnal and day to day variation in ventilatory capacity and vital capacity in healthy adults. Indian J Chest Dis Allied Sci 1969;11:19-25. 11. Rosner SW, Abraham S, Caceres CA: Observer variation in spirometry. Dis Chest 1965;48:265-268.Crossref 12. Dawson A: Reproducibility of spirometric measurements in normal subjects. Am Rev Respir Dis 1965;93:264-268. 13. Pennock BE, Rogers RM, McCaffree DR: Changes in measured spirometric indices. What is significant? Chest 1981;80:97-99.Crossref 14. Nickerson BG, Lemen RJ, Gerdes CB, et al: Within-subject variability and percent change for significance of spirometry in normal subjects and in patients with cystic fibrosis. Am Rev Respir Dis 1980;122:859-866. 15. Hutchinson AA, Erben A, McLennan LA, et al: Intrasubject variability of pulmonary function testing in healthy children. Thorax 1981;36:370-377.Crossref 16. Colton T: Statistics in Medicine . Boston, Little Brown & Co, 1974.
Archives of Internal Medicine – American Medical Association
Published: Jul 1, 1982