Abstract
Rationale The Third National Health and Nutrition Examination Survey
(NHANES III) reference is currently recommended for interpreting
spirometry results, but it is limited by the lack of subjects younger
than 8 years and does not continuously model spirometry across all ages.
Objectives: By collating pediatric data from other large-population
surveys, we have investigated ways of developing reference ranges that
more accurately describe the relationship between spirometric lung
function and height and age within the pediatric age range, and allow a
seamless transition to adulthood.
Methods: Data were obtained from four surveys and included 3,598
subjects aged 4-80 years. The original analyses were sex specific and
limited to non-Hispanic white subjects. An extension of the LMS (lambda,
mu, sigma) method, widely used to construct growth reference charts, was
applied.
Measurements and Main Results: The extended models have four important
advantages over the original NHANES III analysis as follows: (7) they
extend the reference data down to 4 years of age, (2) they incorporate
the relationship between height and age in a way that is biologically
plausible, (3) they provide smoothly changing curves to describe the
transition between childhood and adulthood, and (4) they highlight the
fact that the range of normal values is highly dependent on age.
Conclusions: The modeling technique provides an elegant solution to a
complex and longstanding problem. Furthermore, it provides a
biologically plausible and statistically robust means of developing
continuous reference ranges from early childhood to old age. These
dynamic models provide a platform from which future studies can be
developed to continue to improve the accuracy of reference data for
pulmonary function tests.
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