Am. J. Respir. Crit. Care Med., Vol 151, No. 3, Mar 1995, 675-681.
Selection of spirometric measurements in a clinical trial, the Lung Health Study
RA Wise, J Connett, K Kurnow, J Grill, L Johnson, R Kanner and P Enright
Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21224.
Although current recommendations for spirometry require that the largest
value of FEV1 and FVC should be taken from the largest values of different
maneuvers, the validity of this approach was recently questioned. It has
been suggested that selection of the maneuver with the largest peak flow or
the maneuver with the largest FVC should be used for measurement of
spirometric indices. The present analysis was therefore undertaken to
determine which method of selection of spirometric maneuvers would give the
least short-term variability in a clinical trial population. We examined
the spirometry test sessions from 5,885 individuals with mild to moderate
chronic airflow obstruction who were screened at two visits 24.9 +/- 17.1 d
apart for entry into a multi-center clinical trial, the Lung Health Study.
We compared eight potential selection methods for FEV1 and FVC. Using these
different selection methods, the coefficient of variation ranged from 4.1
to 4.9% for FEV1 and from 3.5 to 5.7% for FVC. The average absolute
difference between the two test sessions ranged from 110 to 123 ml for FEV1
and from 149 to 200 ml for FVC. Although all of the methods gave good
results, the mean of the three highest values and the largest single value
from all maneuvers provided the least short-term variability for both FEV1
and FVC. We therefore conclude that there is no reason to change the
currently recommended selection methods for FEV1 and FVC.
