Historical data on pulmonary function
Collecting new data for the derivation of references values of lung function is both very time consuming and costly. On that account the European Community for Coal and Steel (ECCS, see below) decided to rely on published data. This led to a compilation of publications based on acceptable methods and techniques, and using acceptable criteria for delineating a ‘healthy’ population. Inasmuch as this was possible (not all publications were sufficiently clear in this respect) data from non-smokers were used. However, this was not feasible for all indices.
The predicted FEV1 of Caucasian males (according to acceptable studies) is
shown as an example. The figure on the left depicts the
relationship with length for males aged 35 to 55 yr. There
is fair agreement between the slopes, most lines are pretty
close together, but the differences between the extremes
are large. At 1.8 meter, about the average standing height
of a Dutch male adult, the lowest predicted FEV1 is about 3 L, the highest about 1.5 L more!
The figure on the
left shows how the FEV1 relates to age in Caucasian males with standing heights
between 1.65 and 1.85 m. There is remarkable agreement
about the age coefficient. As both the coefficients for
age and height are so similar in all publications, differences
in predicted values are mainly accounted for by a different
intercept. The reason for this is obscure. It probably
relates to differences in the selection of subjects, and
in apparatus, methods and techniques applied.
Predicted values according to most prediction equations came pretty close. Hence the set of prediction equations from acceptable studies was used to derive new regression equations that are in fact the mean of published equations. Whilst the procedure is not ideal, the equations are widely used and therefore seem to be useful in practice.
See also:
Reference values for children
and adolescents
SpirXpert software
ECCS 1983
Quanjer PhH (ed.) Standardized lung
function testing. Bull Eur Physiopathol Respir 1983; 19
suppl. 5: 45-51.