Comparing reference values - 2
On
an absolute scale (liter) differences in predicted FEV1
in particularly the 6-18 yr age range often appear to be small and
therefore insignificant. However, when expressed on a relative scale
such differences can be appreciable, and often exhibit a trend.
The usual pattern is that the predicted FEV1
is too low in the youngest children and in the older adolescents,
and too high at about age 10-11 yr. This implies that one may undestimate
airway obstruction on the basis of FEV1
in a 6-7 yr old child; since the natural growth of FEV1
is subsequently systematically less than the predicted one this
will spuriously introduce a trend of 'deteriorating' lung function
until the end of the growth spurt. After that actual growth in FEV1
is generally larger than the predicted one, spuriously introducing
a trend towards 'improvement' in the level of FEV1.
This trend seems te be best circumvented by using age-specific regression
equations, or those which in some form take age-height interaction
into account [1-4].
- Wang X, Dockery DW, Wypij D, Fay ME, Ferris BG. Pulmonary function between 6 and 18 years of age. Pediatr Pulmonol 1993 15: 75-88.
- Forche G, Stadlober E, Harnoncourt K: Neue spirometrische Bezugswerte für Kinder, Jugendliche und Erwachsene. Ost. Ärztezeitung 1988; 43, 15/16, 40-42.
- Knudson RJ, Lebowitz MD, Holberg CJ, Burrows B: Changes in the normal maximal expiratory flow-volume curve with growth and aging. Am Rev Respir Dis 1983; 127: 725-734.
- Quanjer PhH, Borsboom GJJM, Brunekreef B, Zach M, Forche G, Cotes JE, Sanchis J, Paoletti P. Spirometric reference values for white European children and adolescents: Polgar revisited. Pediatr Pulmonol 1995; 19: 135-142.
See also:
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Predicted values for FEV1, FVC and FEV1%FVC in adults
Predicted values for FEV1, FVC and FEV1%FVC in children and
adolescents